Computer (February 2005)

Innovative Technology for Computer Professionals

February 2005

Creating and Protecting Digital Worlds Ender’s Game Redux TEAM LinG - Live, Informative, Non-cost and Genuine!

h t t p : / / w w w. c o m p u t e r. o r g

Behind the Scenes at Micro-37

Innovative Technology for Computer Professionals

February 2005,Volume 38, Number 2

COMPUTING PRACTICES 26 Local Search: The Internet Is the Yellow Pages Marty Himmelstein The proposed Internet-Derived Yellow Pages provides a framework for combining Internet-derived content with the trust and fairness that characterize the printed Yellow Pages.

C O V E R F E AT U R E S GUEST EDITOR’S INTRODUCTION

36 Nanoscale Design & Test Challenges Yervant Zorian The silicon-scaling revolution presents a plethora of challenges as technology progresses into the nanoscale era.

43 Robust System Design with Built-In Soft-Error Resilience Subhasish Mitra, Norbert Seifert, Ming Zhang, Quan Shi, and Kee Sup Kim A system’s susceptibility to transient errors increases in advanced technologies, making the incorporation of effective protection mechanisms into chip designs essential. A new design paradigm reuses design-for-testability and debug resources to eliminate such errors.

53 Transistor-Level Optimization of Digital Designs with Flex Cells

Cover design and artwork by Dirk Hagner

ABOUT THIS ISSUE

nlike previous generations, 90-nanometer design and beyond presents new, and sometimes unforeseen, challenges: very high design and tooling costs, high transistor leakage causing power management issues, and environmentally induced soft errors. In this issue, we take a look at efforts by the design and test community to answer these challenges to Moore’s law.

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Rob Roy, Debashis Bhattacharya, and Vamsi Boppana The flex-cell approach provides an optimally tuned set of building blocks for integrated circuit design when optimality is measured using metrics such as clock speed, die size, and power consumption.

63 Hardware/Software Interface Codesign for Embedded Systems Ahmed A. Jerraya and Wayne Wolf A codesign approach will enable the integration of hardware and software components in heterogeneous multiprocessors. The authors analyze the evolution of this approach and define a long-term roadmap for future success.

R E S E A R C H F E AT U R E 71 A New Framework for Power Estimation of Embedded Systems Claudio Talarico, Jerzy W. Rozenblit, Vinod Malhotra, and Albert Stritter A proposed modular framework for assessing power consumption of embedded systems early in the design cycle can be extended to any performance metric and uses a high level of abstraction, leading to a faster execution time.

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OPINION 8

At Random Behind the Scenes at Micro-37 Bob Colwell

NEWS 14

Industry Trends Developments Advance Web Conferencing David Geer

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Technology News Telecom Carriers Actively Pursue Passive Optical Networks George Lawton

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News Briefs One-Handed Keyboard Helps Mobile and Disabled Workers ■ US Increases Quota for Controversial Visas ■ Engineers Begin Addressing “Talking Spam”

MEMBERSHIP NEWS 81

Computer Society Connection

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Call and Calendar COLUMNS

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Entertainment Computing Ender’s Game Redux Michael Macedonia

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Invisible Computing Creating and Protecting Digital Worlds Bill N. Schilit and Roy Want

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The Profession

NEXT MONTH:

Smart Things and Places

The Profession and the Big Picture Neville Holmes

D E PA R T M E N T S

Membership Magazine of the

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Article Summaries

6

Letters

12

32 & 16

40

IEEE Computer Society Membership Application

79

Products

80

Bookshelf

88

Career Opportunities

94

Advertiser/Product Index

COPYRIGHT © 2005 BY THE INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS INC. ALL RIGHTS RESERVED. ABSTRACTING IS PERMITTED WITH CREDIT TO THE SOURCE. LIBRARIES ARE PERMITTED TO PHOTOCOPY BEYOND THE LIMITS OF US COPYRIGHT LAW FOR PRIVATE USE OF PATRONS: (1) THOSE POST-1977 ARTICLES THAT CARRY A CODE AT THE BOTTOM OF THE FIRST PAGE, PROVIDED THE PER-COPY FEE INDICATED IN THE CODE IS PAID THROUGH THE COPYRIGHT CLEARANCE CENTER, 222 ROSEWOOD DR., DANVERS, MA 01923; (2) PRE1978 ARTICLES WITHOUT FEE. FOR OTHER COPYING, REPRINT, OR REPUBLICATION PERMISSION, WRITE TO COPYRIGHTS AND PERMISSIONS DEPARTMENT, IEEE PUBLICATIONS ADMINISTRATION, 445 HOES LANE, P.O. BOX 1331, PISCATAWAY, NJ 08855-1331.

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Innovative Technology for Computer Professionals

Editor in Chief

Computing Practices

Special Issues

Doris L. Carver

Rohit Kapur

Bill Schilit

Louisiana State University [email protected]

[email protected]

[email protected]

Associate Editors in Chief

Perspectives

Web Editor

Bob Colwell

Ron Vetter

[email protected]

[email protected]

Bill N. Schilit Intel

Research Features

Kathleen Swigger

Kathleen Swigger

University of North Texas

[email protected]

Area Editors

Column Editors

Computer Architectures Douglas C. Burger

At Random Bob Colwell Bookshelf Michael J. Lutz

University of Texas at Austin

Databases/Software Michael R. Blaha

University of Maryland

Standards Jack Cole

OMT Associates Inc.

Graphics and Multimedia Oliver Bimber

Embedded Computing Wayne Wolf

Advisory Panel

Bauhaus University Weimar

Princeton University

University of Virginia

Information and Data Management Naren Ramakrishnan

Entertainment Computing Michael R. Macedonia

Thomas Cain

Georgia Tech Research Institute

Virginia Tech

Ralph Cavin

IT Systems Perspectives Richard G. Mathieu

Semiconductor Research Corp.

IBM Almaden Research Center

Networking Jonathan Liu University of Florida

Software H. Dieter Rombach

Carl K. Chang [email protected]

CS Publications Board Security Bill Arbaugh

Rochester Institute of Technology

Multimedia Savitha Srinivasan

2004 IEEE Computer Society President

US Army Research Laboratory

James H. Aylor

University of Pittsburgh

Michael R. Williams (chair), Michael R. Blaha, Roger U. Fujii, Sorel Reisman, Jon Rokne, Bill N. Schilit, Nigel Shadbolt, Linda Shafer, Steven L. Tanimoto, Anand Tripathi

CS Magazine Operations Committee Bill Schilit (chair), Jean Bacon, Pradip Bose, Doris L. Carver, Norman Chonacky, George Cybenko, John C. Dill, Frank E. Ferrante, Robert E. Filman, Forouzan Golshani, David Alan Grier, Rajesh Gupta, Warren Harrison, James Hendler, M. Satyanarayanan

Ron Hoelzeman

St. Louis University

University of Pittsburgh

Invisible Computing Bill N. Schilit

Edward A. Parrish Worcester Polytechnic Institute

Intel

Ron Vetter

The Profession Neville Holmes

Alf Weaver

University of North Carolina at Wilmington

University of Tasmania

University of Virginia

AG Software Engineering

Dan Cooke Texas Tech University

Administrative Staff

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Chris Nelson

Senior Acquisitions Editor [email protected]

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Bryan Sallis

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Manuscript Assistant

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Design Larry Bauer Dirk Hagner Production Larry Bauer

Senior Editor

Lee Garber Senior News Editor

Executive Director David W. Hennage Publisher Angela Burgess

Business Development Manager Sandy Brown Senior Advertising Coordinator Marian Anderson

Circulation: Computer (ISSN 0018-9162) is published monthly by the IEEE Computer Society. IEEE Headquarters, Three Park Avenue, 17th Floor, New York, NY 100165997; IEEE Computer Society Publications Office, 10662 Los Vaqueros Circle, PO Box 3014, Los Alamitos, CA 90720-1314; voice +1 714 821 8380; fax +1 714 821 4010; IEEE Computer Society Headquarters,1730 Massachusetts Ave. NW, Washington, DC 20036-1903. IEEE Computer Society membership includes $19 for a subscription to Computer magazine. Nonmember subscription rate available upon request. Single-copy prices: members $20.00; nonmembers $94.00. Postmaster: Send undelivered copies and address changes to Computer, IEEE Membership Processing Dept., 445 Hoes Lane, Piscataway, NJ 08855. Periodicals Postage Paid at New York, New York, and at additional mailing offices. Canadian GST #125634188. Canada Post Corporation (Canadian distribution) publications mail agreement number 40013885. Return undeliverable Canadian addresses to PO Box 122, Niagara Falls, ON L2E 6S8 Canada. Printed in USA. Editorial: Unless otherwise stated, bylined articles, as well as product and service descriptions, reflect the author’s or firm’s opinion. Inclusion in Computer does not necessarily constitute endorsement by the IEEE or the Computer Society. All submissions are subject to editing for style, clarity, and space.

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ARTICLE SUMMARIES Local Search: The Internet Is the Yellow Pages pp. 26-34 Marty Himmelstein

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he Internet is not meeting its potential for delivering geographically oriented information. Sometimes the information people seek is on the Internet, but the tools for locating it are inadequate. In other cases, our industry has not developed the counterparts needed to replace traditional delivery methods such as the printed Yellow Pages. The Internet Yellow Pages, currently the main source of local content on the Internet, are reliable, but they are also shallow, slow to change, centralized, and expensive. Their primary data sources are printed telephone directories. They do not use the Internet’s resources in any meaningful way. Geosearch, a geoenabled search engine that lets people search for Web pages that contain geographic markers within a specified geographic area, demonstrates that the Internet is a rich source of local content. It also demonstrates the many advantages that postal addresses have as a key for accessing this content, especially when the content pertains to the activities of daily life.

Robust System Design with Built-In Soft-Error Resilience pp. 43-52 Subhasish Mitra, Norbert Seifert, Ming Zhang, Quan Shi, and Kee Sup Kim

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oft errors, also called single-event upsets, are radiation-induced transient errors caused by neutrons generated from cosmic rays and alpha particles generated by packaging material. Traditionally, soft errors were regarded as a major concern only for space applications. Yet, for designs manufactured at advanced technology nodes—such as 90 nm or 65 nm—system-level soft errors occur more frequently than in previous generations. Chip designers must address soft errors very early, starting from the prod-

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uct definition phase and continuing through the architecture planning, circuit design, logic design, and postlayout phases. The effects of soft errors in sequential elements such as flip-flops, latches, and combinational logic must be evaluated, and effective protection mechanisms incorporated into the design.

Transistor-Level Optimization of Digital Designs with Flex Cells pp. 53-61 Rob Roy, Debashis Bhattacharya, and Vamsi Boppana

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ver the years, it has become commonplace to perform various forms of manual intervention on designs generated using automated flows. The quest to overcome the limitations of standard-cell-based design methods leads naturally to the creation of new design- and context-specific cells— designated flex cells—during the process of optimizing a given digital design. Flexcell-based design optimization automates the creation of tactical cells. The flex-cell approach, either alone or in combination with standard cells, provides an optimally tuned set of building blocks for the target IC design, which measures optimality against accepted and quantifiably definable metrics such as clock speed, die size, and power consumption. By allowing manipulation of the transistor-level structures, flex cells open up a new dimension in the optimization of automatically created designs.

Hardware/Software Interface Codesign for Embedded Systems pp. 63-69 Ahmed A. Jerraya and Wayne Wolf

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echnological evolution—particularly shrinking silicon fabrication geometries—is enabling the integration of complex platforms in a single system on chip. In addition to specific hardware subsystems, a modern SoC also can include one or several CPU sub-

systems to execute software and sophisticated interconnects. Mastering the design of these embedded systems challenges both the system and semiconductor houses that used to apply a software- or hardware-only strategy. In addition to classic software and hardware, SoC engineers must design hardware-dependent software and software-dependent hardware. Codesigning these HW/SW interfaces requires a new kind of engineer who understands both hardware and software design. Providing SoCs consisting of an assembly of processors executing tasks concurrently will require design methodologies to focus on selecting and using either programmable or dedicated processors in place of the gates and arithmetic logic units that current methods use.

A New Framework for Power Estimation of Embedded Systems pp. 71-78 Claudio Talarico, Jerzy W. Rozenblit, Vinod Malhotra, and Albert Stritter

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mong the many metrics used to characterize the quality of an embedded system-on-chip design, power consumption has emerged as one of the most important. This is largely due to the proliferation of mobile batterypowered computing devices, the increasing speed and density of CMOS (complementary metal-oxide semiconductor) VLSI (very large-scale integration) circuits, and continuous shrinking of the transistor feature size of deep-submicron technologies. The authors have developed a technique that derives power figures from the execution of high-level models. This technique makes it possible to assess embedded SoC designs much earlier in the design cycle, contributing to sounder decisions throughout the entire development process and leading to a faster execution time. To validate their methodology, the authors applied it to a peripheral core—a baud rate generator—and compared the results with those obtained using a gatelevel approach.

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L E T TERS

SYSTEM RECOVERY ALTERNATIVES The authors of “Recovery-Oriented Computing: Building Multitier Dependability” (George Candea et al., Nov. 2004, pp. 60-67) mentioned several techniques for recovering from inevitable system failures, including microreboot and system-level undo. I agree in principle that “A first-lineof-defense recovery mechanism should be low cost and low overhead, with a good probability of repairing the problem…” In the event of a hardware or software failure, the basic objectives are getting the system back to normal operation in the shortest time and restoring individual files and folders as quickly as possible. In some cases, a reboot can remedy minor problems and serve as “a universal form of recovery for many software failures, even when the exact causes of failure are unknown.” However, unidentified problems frequently recur, resulting in a complete system malfunction. In this circumstance, rebooting merely postpones the inevitable. The traditional tape backup technology is increasingly becoming a secondary option because the stored files can be corrupt or blank when restored. Moreover, manually rebuilding and restoring data from tape backups or reinstalling it from scratch can take hours, which is not acceptable for most businesses these days. Disk-to-disk backup with system imaging offers a viable option for ensuring against system failure. This technology can store either individual files or entire directories without requiring backup software. IT administrators can use online server imaging to create a full image of the system and to perform frequent diskto-disk backup of data files. With system imaging, backups evolve from merely being a disaster recovery option to become an integral part of the information management process. Hong-Lok Li Vancouver, B.C. [email protected] 6

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The authors respond: Great observations. Microrebooting aims to complement—rather than replace—existing, more expensive high-availability techniques such as redundancy and failover. It is not a cure-all. Our paper on “crash-only software” (www.stanford.edu/~candea/papers/) presents the design of systems optimized for shutdown-by-crashing. In these systems, the effectiveness of microrebooting is maximized. Failures whose root causes recur deterministically—a problem for any form of recovery—are handled by recognizing the repeating failure pattern in a recovery manager and employing an alternate form of reovery. Extensive logging at runtime and recovery time provides the means to identify impending larger problems. In this case, if microrebooting can delay a problem, operators gain time to prepare for handling it when it strikes. All these topics and more are covered at the URL provided above.

THE RELEVANCE OF COMPUTER SCIENCE RESEARCH Reading the December The Profession column (Simone Santini, “Determining Computing Science’s Role,” pp. 128, 126-127) brings up several questions: Is this column relevant? Is computer science relevant? Are universities relevant? The author illustrates no reasons for or benefits from pure computer science research. He illustrates no accomplishments of this research in the past half century. Why should society be obligated to pay the salaries of pursuers of pure research? There are nonscientists who

do accomplish things, some of which have a huge impact on society—not all of them economic. Since computer science is still a field where a lone researcher could accomplish something significant, perhaps pure computer science researchers should retreat into their garages to do their work. The author bemoans the fact that economic factors are driving research, while his essential complaint is that not enough money is going into pure research. This seems rather self-contradictory. He is unhappy about universities churning out professionals who can actually contribute to society. God forbid! I’m glad this is happening at long last, with the captains of academia reluctantly coming out of their caves to see the light of reality. Let’s remember that computer science was born because Turing wanted to help the war effort, not because he had too much idle time on his hands. This column appears to exist either simply to be a voice for disillusioned academia or to generate controversy. If this is indeed a column about “the profession,” let’s hear from some professionals. Otherwise, print something else that might be useful because useful information is the only thing I’ll pay for. Aditya Garg [email protected] The author responds: In what sense are the terms “relevant” and “significant” to be taken here? Economically relevant? Industrially significant? Nothing else? If I agreed on the exclusivity of these criteria, I could simply resort to the many examples of technical (and economic) breakthroughs generated by pure research that probably never would have happened in the frantically application-oriented world of industrial development. To stay on familiar ground: Turing published his Entscheidungsproblem (the “Turing machine” paper) article in 1936, well before World War II. Its

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origins are indeed in the mathematical literature—in one of the 23 unsolved problems that Hilbert outlined at the first mathematical congress in 1900. Other examples, from Fourier to Maxwell, abound: Creativity often— although not always, of course— comes to life as an epiphenomenon of unattached culture. Industrial research is useful and important, but it can’t be our only model. But to artificially restrict ourselves to this monochromatic reading of the term “relevant” would miss my point: Computers probably would have been developed even without Turing and Von Neumann (another pure mathematician). But the point is that to reduce the entire human experience to

industrial productivity would be to deny our intellectual richness. One reason that people work is to carve a space in their life in which they can pursue their own interests. Education—not just in universities— should take this essential fact into account. If industrial ethics is the only thing that matters, if the only purpose of education is to make us productive, then the education system fails to give us the intellectual tools needed to fully experience an essential aspect of our lives. The idea that production is the mover of history is a bit Marxist, but even Marx’s ideal man would work in a factory in the morning, play violin in the afternoon, and go to the theater in

the evening. Even the most econocentric view includes a cultural life, in the discipline of one’s choice. I don’t complain that not enough money is going to research; I do complain that not enough public money is going there. Universities do have too much private money—witness the gigantism and scientific poverty of many a university project. Finally, one goal of my column was indeed to generate controversy, for a discipline without controversy is condemned to wither and die.

We welcome your letters. Send them to [email protected].

The 2005 IEEE International Conference on Information Reuse and Integration (IEEE IRI-2005) Knowledge Acquisition and Management






August 15-17, 2005 Las Vegas Hilton, Las Vegas, Nevada, USA

http://www.cs.fiu.edu/IRI05 Sponsored by the IEEE Systems, Man and Cybernetics Society

This year's conference theme addresses all aspects of Knowledge Acquisition and Management as they relate to the design, implementation, and maintenance of large-scale systems. This theme was selected to reflect the interdependency among AI, multimedia, networking, software and systems engineering, telecommunications, etc. within the context of reuse and integration. The IEEE International Conference on Information Reuse and Integration will feature contributed as well as invited papers. Theoretical and applied papers are both included in this call. The conference program will include special sessions and open forum workshops.

Instructions for Authors: Papers reporting original and unpublished research results pertaining to the above and related topics are solicited. Full paper manuscripts must be in English of length 4 to 6 pages (using the IEEE two-column template). Submissions should include the title, author(s), affiliation(s), e-mail address(es), tel/fax numbers, abstract, and postal address(es) on the first page. Papers should be submitted at the conference web site: http://www.cs.fiu.edu/IRI05. If web submission is not possible, manuscripts should be sent as an attachment via email to one of the Program Chairs listed on IRI 2005 web site on or before the deadline date of March 31, 2005. The attachment must be in .pdf (preferred) or word.doc format. The subject of the email must be “IEEE IRI 2005 Submission.” Papers will be selected based on their originality, timeliness, significance, relevance, and clarity of presentation. Authors should certify that their papers represent substantially new work and are previously unpublished. Organizers of prospective special sessions and panels are invited to submit proposals and should contact one of the Program Chairs directly as soon as possible, but no later than January 31, 2005. Paper submission implies the intent of at least one of the authors to register and present the paper, if accepted. Authors of selected papers that are also presented at the conference will be invited to submit expanded versions of their papers for review for publication in the appropriate IEEE SMC Transactions.

Important Dates: January 31, 2005 March 31, 2005 May 20, 2005 June 15, 2005 July 1, 2005 August 15-17, 2005

Proposals for special sessions, panels, tutorials, and workshops Paper submission deadline Notification of acceptance Camera-ready due Conference registration Conference

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Behind the Scenes at Micro-37 Bob Colwell

ver the years, I have attended or helped organize approximately 17.7 cajillion conferences. Some were too big, or too commercial, or too impersonal. Others sported a program that was heavy on impressive titles and inspired formatting, but unencumbered by actual useful technical content. Some were incredible: The attendees bounced from one utterly engrossing technical discussion to another, with the top engineers and researchers in the field expounding in their best take-no-prisoners styles. Surely that is what conferences are all about—placing very smart, intense people in close enough proximity to generate sparks.

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BEWARE OF E-MAIL MESSAGES PUTTING YOU IN CHARGE

The best conferences place very smart, intense people in close enough proximity to generate sparks.

A SPEAKER’S QUANDARY The Supercomputing 90 conference in New York City has a special place in my memory. I was delivering the last of the papers I had written at Multiflow—Multiflow having exited the business a few months prior. About 10 minutes into my talk, the doors at the back of the ballroom burst open, and a New York City fireman, bedecked in full firefighting regalia replete with hat and axe, hustled down the main aisle and stopped. He said, “There is a fire on the roof of this building. Has anyone smelled any smoke in this room?” The mental gap between the intricacies of how Multiflow’s machines worked and the implications of sitting 8

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When I announced my decision, not one member of the audience got up and left. The day got even stranger about two hours later, when I entered the men’s room one floor up, only to find several policemen in it. Startled, I asked one of them if there was something I should know about this particular facility. He said, “Nah, there was a shooting in here about an hour ago, and we’re just following up on that. You wouldn’t happen to know anything about that, would you?” Trying not to look guilty, I said no, and eagerly volunteered to find another restroom elsewhere.

in a building that is on fire was too wide for most of the audience to bridge. But a few looked at each other, quickly reached a consensus, and said, “No.” Whereupon the fireman said, “Well, you can either evacuate the building or not—your choice,” and left the room. This left me, as the guy with the microphone in his hand, in something of a quandary. The options seemed to range from complete denial (“Fireman? What fireman?”) to tearing off my mic and racing for the doors. After a few seconds, I decided that if we were in any real danger, the fireman would have been a bit more direct with his advice, and I opted to carry on.

In January 2003, I got an e-mail message asking if I’d be willing to be general co-chair of the 2004 Micro-37 conference, along with Kevin Skadron of the University of Virginia. I bravely replied, “Maybe.” After checking around a bit, and enlisting the formidable organizing skills of my wife, Ellen, I accepted. The first question was where to hold the conference. When you work for an organization that sends you to conferences, sometimes they will look askance at the venue. For example, places where the postcards have a lot of hula skirts on them are sometimes deprecated, but if they agree to send you, your travel expenses are covered. If you are an independent consultant like me, you can readily give yourself approval for travel, but you end up footing the bill. Since my wife would also be attending, the travel costs would be double. This line of reasoning strongly suggested that Portland, Oregon, where I happen to live, was a great place to have the conference. Now we needed a hotel. I quickly ruled out cold-calling all of the local hotels, and did what I always do when in doubt: I Googled. It turned out that the city has an online conference plan-

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ning utility. I guessed at the number of attendees, and ended up with a list of about five hotels that could handle a conference of our size on the dates we needed. Ellen and I visited three of the candidate hotels in the summer of 2003. It quickly became clear that all three really wanted our business; apparently Portland isn’t always the city of choice for conferences in December. The hotel we ended up choosing really put on a full-court press. They lined up all of the hotel staff for our visit, each prepared to demonstrate their unique contributions to our conference. We especially enjoyed interrogating the chef who makes the desserts. We were very thorough about checking out the chocolate chip cookies. No detail is too small if you’re planning a world-class conclave.

CONFERENCE COMMITTEE ASSIGNMENTS The main thing that any conference must get right is the paper selection process. This issue was quickly dispensed with by putting John Shen and Antonio González in charge of it. Organizing committees always have a few nerve-wracking months between issuing the call for papers and receiving enough submissions to make the event worth holding. If you’ve ever hosted a social event, the feeling you have just after sending out the invitations is the same: “What if nobody comes?” Input from the Micro steering committee and good judgment and connections from Kevin Skadron rounded out the rest of the conference committee.

FINANCES Among the most important aspects of any conference are its finances. At first blush, this would not seem to be any great mystery: Multiply the number of conference attendees by the registration fee, add in whatever corporate donations have been successfully wheedled, and subtract the expenses. In fact, that is the right algo-

rithm, but, unfortunately, the data needed to execute it is not available at the required times.

Take-away gifts It is customary to give each conference attendee a take-away gift. This is often a T-shirt, backpack, laser pointer, flashlight, coffee mug, and so on, marked with the conference name and adorned with the logos of the corporate sponsors.

No detail is too small if you’re planning a world-class conclave.

I promised to cajole my network of corporate friends in our pursuit of an outstanding conference. In the end, Intel, Cadence, IBM and Texas Instruments came through for us. Special thanks go to Intel for their outstanding support of this and many other conferences, both directly and indirectly. Besides contributing many conference committee members (and conference attendees), Intel also made substantial cash donations. Intel even helped us avoid the odious prospect of renting four $1,000 VGA projectors at $300 per day by lending the projectors as well.

ARTS AND CRAFTS Our local arrangements chair, Srikanth Srinivasan, devoted many hours to investigating the various options and proposed that we give each attendee two handouts: a polo shirt and a collapsible umbrella. Was he finished with this job? Definitely not. How many shirts? What sizes? Embroidered how and where? What color? Too many shirts, and it would cost the conference a lot of money; too few, and late registrants would pay the full registration fee and receive no shirt in return. I was not particularly worried about having too many shirts. They were not terribly expensive, and I figured we could donate any extras to help local homeless relief efforts. Fortunately, though, someone pointed out that it was unclear how having Portland’s homeless population sporting shirts that said “Micro-37” would be interpreted by the public or by prospective future Micro attendees.

Corporate support One piece of helpful information I received at the beginning of our conference preparations was that the difference between a successful conference and an outstanding one depends on the degree of direct corporate support available.

As we arrived at the conference for the first day of workshops, we suddenly realized that we didn’t have any signs saying “Micro-37.” Ellen and I took on the challenge of rectifying this omission. I first searched the Internet using keywords like signs and banners and found that I could either buy something from Microsoft or I could find a font I liked and just print the letters out one by one and paste them to something. For the next few hours, we printed the letters, cut them out with a razor blade, and then glued them to a standard foam board from an art store. It was a surreal experience, staying up well past midnight, gluing paper letters to a foam core board so the signs could be used at one of the highest tech conferences in the world the next day.

DOING THE MATH Ellen also worked out how many meals the conference would provide, what types they would be (buffet versus plated), what food would be available at each, how many types of diets the food would need to cover, how many breaks would be catered, and so on. Guessing how many people would be there for lunch at the tutorials was more of a challenge than we expected. It’s a complex equation of how many people have actually registered, how February 2005

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At Random

many you think might show up at the door, how many might go out to lunch on their own, and how many show up early for the conference and figure they’ll just drop in for lunch. Then we realized that we forgot to include the organizers in the totals. Luckily the hotel staff was very experienced, and they always had more food at the ready. Watch out for what type of lunch you order, though. Choosing a particular type of lunch can cause the hotel staff to assume a sit-down plated experience, and you could find them rearranging the main conference room from classroom seating to round-table restaurant seating just before the morning’s technical session is about to begin. (I wish that were only hypothetical.)

tration table and inquired about the leftover umbrellas, for which we had lowered the price to $5. She was very enthused about the umbrellas until she saw the corporate logos printed on them.We don’t know which of our sponsors’ logos had this effect on her, but when she opened up one of them, it was clear that the geek factor exceeded her threshold of tolerance, and she declined to make a purchase.

Who knew that a technical conference needs someone with retail experience to plan the markdowns?

Getting charged for everything The hotel was very accommodating but, as with most hotels, they charge for each thing they do. Need an extension cord for the day? Five dollars, please. So when I noticed that a woman who was not associated with our conference was busy stuffing bottles of Coke into her bag, I marched over and looked interested in her activities. Without saying a word, she reversed direction, put the bottles back, and casually strolled away.

Managing markdowns During the last days of the conference, we realized we had surplus umbrellas and polo shirts and decided to try to “move the merchandise” by selling them for reduced prices. The people who attend Micro are not stupid. One of them said, “First, the shirts were $20. Now they’re $10. I’m thinking that tomorrow they’ll be $5, and you’ll be giving them away at the end. I’m going to wait until then.” Who knew that a technical conference really needs someone with retail experience to plan out when and how to mark down the leftover merchandise? One woman who was not associated with Micro came up to the regis10

OUR EXCURSION There are many nice things to see and do within a reasonable bus drive of Portland. We have the beautiful Oregon coast, Mt. St. Helens, the Columbia Gorge with its picturesque waterfalls, Mt. Hood with its hiking trails and skiing, and the Columbia and Willamette rivers on which boat tours are available. The only constraints to planning an excursion for the conference attendees were that in December in Portland, it gets dark early and it rains a lot. After considering many different possibilities, Sri and Ellen eventually settled on having a dinner at the Evergreen Aviation Museum in McMinnville, Oregon. The museum is the home of Howard Hughes’s gigantic wooden airplane, “The Spruce Goose,” as well as an SR-71 spy plane and numerous helicopters and fixedwing planes of every size and shape. After a great deal of research and discussion, we found a caterer and selected a menu that would be appropriate for a wide range of diners with different diet requirements, including vegetarian, vegan, and kosher. Then we needed to decide on a program for the evening.

Planning the program The SR-71 is one of my favorite airplanes, and its chief designer, Kelly Johnson, is one of my engineering heroes. When we visited the museum to make arrangements for the excursion, I smiled when I saw how they had arranged the SR-71: It was nestled under the right wing of the Spruce Goose. This was ironic because, as Johnson states in his autobiography, he and Hughes were contemporaries. However, Johnson had a low opinion of Hughes’s flying skills, and, on at least one occasion, he attempted to wrest the controls away from Hughes, an action Hughes did not appreciate. Since the excursion was going to be at the museum, I had the bright idea that we should hire an SR-71 pilot to speak to our group about his experiences with that plane. Discussions with a prospective pilot/ speaker, selected from among several who advertise their services on the Internet, made two things apparent: • Short of a sponsor who would be willing to directly underwrite a few thousand more dollars for such a speaker, we couldn’t afford this. • Being in the midst of a war that is quite unpopular overseas may not be an appropriate time to subject international conference attendees to a lecture by a representative of the American military. I reluctantly dropped this idea.

A treasure hunt challenge Prior to dinner, the museum had some clue sheets available for attendees who like the challenge of participating in a treasure hunt. Ellen bought prizes at the museum’s gift shop to give to the first three finishers with the right answers. We were a little concerned that more than three participants might have the correct answers. But when Ellen graded the clue sheets, it was clear to whom the prizes would go: Only three

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attendees had signed names on their sheets. I still think Micro attendees are inordinately intelligent, but their treasurehunt results do not constitute evidence for this contention.

“Free” entertainment The after-dinner entertainment that we finally decided on was free—me, playing the guitar. If this seems unlikely, check the Micro-37 Web site (www.microarch.org/micro37) for photographic evidence. Although it was a bit daunting to play with various aircraft looming over my shoulder, and the acoustics of the gigantic hall were such that I really couldn’t hear myself all that well, the gig went off just fine. At least it did until someone decided to play a practical joke in the middle of my solo ver-

sion of Steely Dan’s “Josie.” When they opened my guitar case and started throwing coins into it, I found that “Josie” is even more difficult to play when I’m laughing. After the conference was over, the IEEE informed us that if any music is played at an IEEE event, either live or prerecorded, royalties are due to both BMI and ASCAP, which together hold nearly all of the music copyrights in existence. It isn’t a huge amount of money, and I don’t begrudge the musicians and copyright holders their due, but it still seems weird that my playing for free actually cost the conference some money.

O

verall, Micro-37 went very smoothly and the organizing committee got many thanks and

SCHOLARSHIP MONEY FOR STUDENT LEADERS Student members active in IEEE Computer Society chapters are eligible for the Richard E. Merwin Student Scholarship. Up to ten $4,000 scholarships are available.

Application deadline: 31 May

congratulations. We learned a lot: Remember the organizers when estimating lunch attendees for the workshops and tutorials. Keep an eye on your Coke bottles. Get Kevin Skadron as your co-chair and Sri for local arrangements if possible. Make sure Ellen is available to help with organization. Don’t sing, unless you can prove you wrote the music yourself. And one more thing: Lock your guitar case. ■

Bob Colwell was Intel’s chief IA32 architect through the Pentium II, III, and 4 microprocessors. He is now an independent consultant. Contact him at [email protected].

INTERNATIONAL CONFERENCES SAN DIEGO, USA JUNE 2005

Call For Papers now underway •International Conference on Computer Science and its Applications (June 28-30) • International Advanced Database Conference (June 28-30) • International Conference on Data Management for Real-Life Problems in Biomedicine (June 27-30)

Investing in Students

Please visit for details

www.conferencehome.com

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11

1973 1989 1973 1989 •

3 2 & 16 YEARS AGO

•

FEBRUARY 1973 SOCIAL EFFECTS (p. 8). “The National Science Foundation (NSF) has announced formation of a Computer Impact on Society section to support research designed to help better understand the impact computers have on our way of life. “The new section, within the Office of Computing Activities, is headed by Dr. Peter G. Lykos and includes … [a] Computer Impact on Organizations program … and a Computer Impact on the Individual program …” COMPUTER COMMUNICATIONS (p. 13). “The challenge that confronts us in the 1970’s is not to design and program a computer system to produce reports that enable individuals to perform functions, but to design and program a computer-communications network which is characterized by computer-controlled performance of the functions. The computer-communications network of the 1970’s should communicate, monitor, compute, control, and maintain cognizance of all its elements while collecting data on-line for off-line processing.” INDUSTRY TREND (p. 19). “The computer industry trend is definitely towards more data communications. New generation computer systems will incorporate the philosophy of real-time remote introduction of information and commands, and the associated responses to the remote terminals.” COMMUNICATIONS PROTOCOL (p. 31). “Bit-oriented control procedures offer a number of advantages over character-oriented procedures and can provide a compatible set of procedures for a wide range of communication system applications. “The Primary/Primary class of procedures is particularly suited to computer-to-computer applications using both point-to-point link configurations and network configurations. These procedures are relatively straightforward, yet provide all of the functionality required for initialization, data transfer and error recovery. The concept of separate Primary and Secondary functions in each station is used as a basis for describing the control procedures. Although system implementation is not necessarily constrained to follow this Primary/Secondary organization, it does provide a good logical basis for system design.” HONEYWELL (p. 35). “Two computers in the small-scale price/performance class have been introduced by Honeywell Inc., marking the second significant expansion of its Series 2000 computer line since it was announced early in 1972.” “The new models will compete on a price-performance basis with computers renting from $2,000 per month and up, such as the IBM System 3, Burroughs 1700, NCR 50 and Univac 9200, Honeywell said.” “The Model 2020 central processor is an entry-level computer with a basic main memory of 24,576 characters that can be increased in six increments to a maximum of 65,536 12

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characters. Cycle time is 2.75 microseconds per character. … Three read/write channels are standard; a fourth is optional on larger 2020 models.” “The Model 2030 central processor is a small-scale computer that provides multiprogramming capabilities usually found on larger, more expensive computer systems. The processor’s main memory of 40,960 characters can be expanded in five increments to a maximum of 98,304 characters. Cycle time is 2.0 microseconds per character. Six read/write channels are standard.” HITACHI COMPUTER SYSTEM (p. 36). “Hitachi, Ltd. has completed and delivered two unusually large scale computer systems to Tokyo University. The Model 8800 Systems execute 5 million instructions per second and have a memory capacity of 8 megabytes. The systems include the following capabilities: 1. Shared memory multiple processors. … 2. Virtual memory, both segmentation and paging. 3. High speed cache memory of 32 kilobytes.” FLEXIBLE DISC FILE (pp. 38-39). “Memorex Corporation has announced the 651 Flexible Disc File for the OEM market. The 651 has a faster access time, increased capacity, a write protect feature and the highest data transfer rate of any competitively priced flexible disc file. …” “An enhanced version of the Memorex 650, the 651 features track-to-track access time of 10 milliseconds with 10 ms settle time. This faster positioning time, along with the 80 ms average latency time, provides improved data throughput. “Data can be formatted in either sector or index mode starting with 132 byte records with 32 records per track (64 tracks) up to 1 record of 4,880 bytes/track making a maximum capacity of 312,500 bytes (2,500,000 bits).” BRAILLE (p. 39). “A computer at the American Printing House for the Blind already has translated 1,000 books and magazines from English into Braille for the nearly half-million sightless persons in the United States. “Donated by the International Business Machines Corporation, the computer has produced more than 398,000 Braille plates from which more than 30 million pages of Braille have been printed. “Finis Davis, Vice President and General Manager of the 114-year-old, non-profit organization, said, ‘We not only are producing literature in Braille with the help of the IBM 7040, but also are conducting intensive research into using it to produce … musical scores and math formulae in Braille, expanding opportunities for sightless persons in these two fields.’” URBAN GAME (p. 40). “A new Urban Game to be developed at Carnegie-Mellon University will aim to show future

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urban managers how a city really works, instead of how it ought to work. “Mr. Jacob Belkin, co-principal investigator and project manager of the Game, says, ‘The effects of new policies— for example, urban renewal—have frequently been different from those intended because planners and managers have had to rely on their perception of how an urban system ought to behave, without really understanding how the system does behave.’”

FEBRUARY 1989 GRAPHICAL USER INTERFACES (p. 8). “Graphical user interfaces for workstation applications are inherently difficult to build without abstractions that simplify the implementation process. To help programmers create such interfaces, we considered the following questions: What sort of interfaces should be supported? What constitutes a good set of programming abstractions for building such interfaces? How does a programmer build an interface given these abstractions? Practical experience has guided our efforts to develop user interface tools that address these questions.” OPTIMIZATION AND ARCHITECTURE (p. 49). “Novel methods of code optimization must influence computer architecture design. From a software viewpoint, an architectural design approach needs to identify the improvement in performance due to any new feature. For example, if a software technique reduces the number of loads and stores in an average program, it alleviates the need for super-fast memory systems in hardware. In a more general vein, if code optimizers work well on simple instructions and poorly on complex instructions, it becomes hard to justify complex instructions in hardware.” ADA COMPILER TECHNOLOGY (p. 52). “Ada is becoming a language of choice for large software projects, but compilers and other language tools may not have kept pace. This article discusses the key technical issues involved in producing high-quality Ada compilers and related support tools. It also addresses some important problems that compiler designers face—for example, determining which deficiencies of existing Ada systems can be attributed to the language and which are simply hard-to-implement features or unresolved issues in Ada compiler technology.” COMPUTING AS A DISCIPLINE (p. 63). “As ACM enters its 42nd year, an old debate continues. Is computer science a science? An engineering discipline? Or merely a technology, an inventor or purveyor of computing commodities? What is the intellectual substance of the discipline? Is it lasting or will it fade within a generation? Do core curricula in computer science and engineering accurately reflect the field? How can theory and lab work be integrated in a computing curriculum? Do core curricula foster competence in computing?”

A DISCIPLINE MATURES (p. 72). “At Snowbird 88, the impression emerged that the discipline of computing was maturing and coming into balance. Many of the problems that plagued the discipline in the late 1970s and 1980s had been solved or alleviated. It was time for the discipline to cease its largely inward-looking activities and branch outward. As an enabling technology for other disciplines, computing should take a more active role in articulating how its own needs, concerns, and basic research impact other disciplines and in collaborating with other disciplines in the evolution of computing applications.” STANDARDS (p. 78). “Movement toward worldwide information networking and the vast capabilities it will provide are being hampered by a lack of agreement on standards that permit equipment and software to interact, according to Irwin Dorros of Bellcore. “‘Without universal internetworking standards, there is no information age,’” the article quotes Dorros as saying. “‘Interface standards are essential to control what could be chaos in a world of many suppliers, many users, many functions, and many technologies.’” DEC PERSONAL COMPUTERS (p. 96). “Digital Equipment entered the PC arena with the announcement of a new family of personal computers, the DECstation 210, 316, and 320. The new IBM-compatible computers run MS-DOS Version 3.3 applications. They come in two configurations: as a basic system with a 31/2-inch floppy drive and VGA graphics adapter, or as a system with VGA graphics adapter, SCSI interface, and hard disk drive.” KEYSTROKE SECURITY (p. 97). “A software package called Electronic Signature Lock, produced by a company of the same name, assigns users electronic signatures based on their unique keystroke dynamics and typing patterns. It reportedly denies system access to unauthorized users even when they have the proper passwords. “The software analyzes the total typing pattern to identify users. It uses a statistical filtering routine to analyze the patterns and determine the probability of proper identity.” MEMORY MANAGEMENT (p. 98). “The Advanced Product Division of Fujitsu Microelectronics offers VLSI implementation of a 25-MHz memory management unit and floating-point controller for the company’ S-25 (MB86901) Sparc RISC processor. “The MMU features 4 Gbytes of virtual address space and 64 Gbytes of physical address space. Up to three levels of page tables support a 4-Kbyte page size.” Editor: Neville Holmes; [email protected].

February 2005

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INDUSTRY TRENDS

Developments Advance Web Conferencing David Geer

W

eb conferencing has become an increasingly desirable option for businesses that don’t want to spend the time and money it takes to fly employees around the world for meetings that don’t require face-to-face contact. “The real key is reducing the time it takes to make a decision,” explained Gerry Kaufhold, principal analyst with In-Stat/MDR, a market research firm. As Figure 1 shows, global revenue from Web conferencing services increased 70 percent—from $450 million to $765 million—between 2002 and 2004 and will reach $1.5 billion by 2007, according to Kaufhold. Traditionally, Web conferencing has been offered as a service hosted by a third-party provider. However, three recent developments are changing the face of the technology. Manufacturers such as eDial, Juniper Networks, Nortel Networks, and Polycom have begun selling Web conferencing server-based software systems that companies can run themselves on their internal network, dedicated servers, or network appliances. This approach enhances security, control over collaborative operations, and integration with existing communications infrastructures. Vendors such as Cisco Systems, with its MeetingPlace application, are now combining service- and server-based conferencing—with some functions

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Sockets Layer technology; proprietary SSL-based approaches; or transportlayer security, a successor to SSL. Typically, providers such as MeetingBridge and WebEx have offered Web conferencing as a service. With these services, users pay providers for each conference and then call up meetings via a Web browser. The providers supply the bandwidth, interface, and tools such as those for coordinating schedules, sending participation instructions, and checking browser settings for compatibility. They also offer technical support to participants.

Advantages

handled by in-house servers and others by service providers—into hybrid approaches that try to provide the best of both worlds. Meanwhile, the Internet Engineering Task Force (IETF) is working on Web conferencing protocols that promise greater flexibility, interoperability, and accessibility.

SERVICE-BASED WEB CONFERENCING Web conferencing enables audio, video, document, and image exchanges among multiple participants over the Internet via technologies such as Webcams; Internet telephony; desktop sharing, which lets users remotely view and control one another’s desktops; whiteboarding; text messaging; and chat. As with instant messaging (IM), with Web conferencing applications, users can determine who is online and available for a meeting via presence technologies. Web conferencing provides security—via encryption, digital certificates, and authentication—using Secure

Participating in a service-based conference costs considerably less than buying a Web conferencing server. Third-party services also eliminate the need for companies to have their own personnel to run, maintain, and fix the conferencing infrastructure. These factors are ideal for companies that want to test the technology before buying their own server or that have small budgets and little or no IT staff. Because the services are easily scalable, users can buy as much conferencing as they need at any time, explained Andy Nilssen, senior analyst with Wainhouse Research, a market analysis firm. In addition, services, with their clearly defined fees, are good for businesses that pass all or some of the conferencing costs on to clients or partners.

Disadvantages In some cases, frequent users can spend more paying for conferences one at a time than buying their own equipment. In addition, Web conferencing services pose a potential security risk because they bypass the normal security policies that a company’s IT personnel establish. Web conferencing services bypass policies because they require application sharing between participants, which enables system access from the outside. Also, conferencing-system bugs can create security vulnerabilities.

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SERVER-BASED WEB CONFERENCING Avaya’s Web Conferencing Server, Juniper’s Secure Meeting, and Polycom’s WebOffice, shown in Figure 2, are examples of server-based Web conferencing systems. In server-based approaches, companies operate their own Web conferencing systems. Their conferencing servers create and maintain a tightly coupled, real-time communications infrastructure under their control. Tightly coupled systems have a central point of control and authorization to enforce conference rules about matters such as who has access to applications, explained Alan Johnston, cochair of the IETF’s Centralized Conferencing Working Group and an MCI distinguished technical member. Client software communicates with the conferencing server in various ways. For example, said Bernadette Golas,

700

North America Europe Asia Rest of the world

600 Millions of US dollars

Hackers can exploit these problems to infect systems with malicious software, intercept documents and other files passed during sessions, or gain entry to conference participants’ systems and files.

500 400 300 200 100 0

2002

2003

2004

2006

2007

Source: In-Stat/MDR

Figure 1. Revenue from Web conferencing services has increased throughout the world, particularly in Asia, and will continue doing so, according to In-Stat/MDR.

Shared documents Router Enterprise

Avaya’s director of product marketing for conferencing solutions, “Users con-

nect to Avaya Web Conferencing Servers through a Java client that they download through their Web browser.” As with service-based systems, servers automatically check each potential conference participant’s availability, identify those who can take part, and record the conference for later use by those who can’t attend. The servers enable a meeting using videoconferencing, Internet telephony, IM, document collaboration, and other communications tools available to participants via their browser-based interface.

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WebOffice server

LAN, WAN, or Internet

Presenter/ conference leader

Participant

Participant

Participant Source: Polycom

Figure 2. With Polycom’s WebOffice server-based conferencing system, a company running its own equipment can start a session on an internal LAN or WAN with participants from inside the organization or over the Internet with participants from outside the enterprise. All participants work over Web browsers. The presenter who is leading the conference is sharing two pages of a document with other participants.

Advantages The server-based approach lets companies, not service providers, decide whether and when to upgrade conferencing systems. Companies also can

integrate their Web conferencing servers with the rest of their communications infrastructure, which offers multiple benefits.

For example, users could work with their company’s single-sign-on capabilities to log in once for multiple network activities, including Web conFebruary 2005

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I n d u s t r y Tr e n d s

ferencing. Integration with a company’s Web directory lets users easily find and work with in-house participants. Participants can use existing network tools, and businesses can avoid running and managing multiple infrastructures. Integrating Web conferencing into familiar infrastructures also shortens the IT personnel’s learning curve. Server-based Web conferencing is more secure, in part because companies control the entire system. In addition, operations based on a company’s single system result in fewer potential vulnerabilities than operations involving both service providers’ and users’ systems. With server-based Web conferencing, companies are aware of security breaches in their own systems more quickly than if third-party providers operate the conferencing application.

Disadvantages Companies that run their own conferencing servers must use their own bandwidth for group meetings, which can be a problem for small businesses. Server-based Web conferencing entails software licensing fees and large equipment costs, including servers; load balancers, which determine the switches to which the system should connect new conference participants to balance the overall switch load; multipoint control units to manage multiuser conferences; and audio bridges for those joining a session only by phone. Also, staff members must learn how to administer and manage server-based systems.

HYBRID SYSTEMS Some companies are providing hybrid Web conferencing systems designed to let users work with the best of both service- and server-based approaches. “A carrier might remotely manage a company’s onsite server,” said eDial CEO Scott Petrack. This could enhance management and keep companies from having to oversee the system. 16

For example, along with providing service-based conferencing, Raindance Communications will manage servers located in companies’ offices, according to Wainhouse’s Nilssen. Some equipment vendors are providing services and servers. For example, Cisco can manage some of a company’s conferencing-related servers by moving them outside security applications, including the firewall. The customer manages the servers that are behind its security applications.

Vendors are working together on wider interoperability. With this approach, people within a company stay on the secure corporate network, and people outside the company, who present more of a security risk, don’t get inside the security applications, explained Troy Trenchard, Cisco’s director of product management for rich-media communications. Companies with their own conferencing servers can benefit from working with service providers, who frequently can better tie in participants outside the enterprise and also can offer enhanced reliability and redundancy for some conferencing services. Along with their advantages, hybrid services can entail both server-based Web conferencing’s initial deployment costs and service-based conferencing’s ongoing service charges.

STANDARDS Traditionally, parties to a Web conference have communicated with one another via proprietary application program interfaces. To conduct Web conferences, users on different platforms that don’t share APIs must spend considerable time and money making their systems interact. Providing more interoperability, which will make conferencing available to larger groups of people regardless of platform, will require standards.

IETF Web conferencing standards are based on its Session Initiation Protocol for initiating and managing interactive communication sessions involving multimedia elements. SIP, a software-implemented protocol, sets up sessions, phone-call routing, authentication, call parameters, and call transfer and termination. The IETF has formed the Centralized Conferencing (XCON) Working Group (www.ietf.org/html.charters/ xcon-charter.html)—which includes companies such as Cisco, Lucent Technologies, and MCI—to develop a standardized suite of protocols for tightly coupled server- or service-based or hybrid multimedia conferences that require strong security and authorization. The suite includes the IETF’s SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions) and IP telephony standards. XCON will replace many of the hard-to-use proprietary APIs that currently support multivendor interoperability, said the IETF’s Johnston. Instead, the standard would create a few interoperable APIs. In addition to enhancing interoperability, XCON would eliminate the time and money companies spend to develop proprietary APIs. XCON systems have a standardized client and conferencing server. The server enforces and manipulates media-usage policies, including mediacomposition rules that govern the union of different media such as voice, video, and IM during a session, according to Johnston. The IETF’s Media Policy Control Protocol defines the controls available to participants and the conferenceserver administrator for manipulating the media policy applicable to a specific session. The media server includes mixers that combine and properly mix video, audio, and other streams and distribute them to participants. This is done in either high-capacity digital signal processors or lower-capacity, lowercost software.

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XCON also works with a conference policy, a set of rules that control various aspects of a session, including the access that conference administrators, participants, and applications have to various media and the ways that they can communicate with one another. For example, for a particular session, XCON can include a list of users authorized to participate in a conference. A node can also use XCON protocols to query a conference server to learn what media types, such as Internet telephony or video, it supports. Conference administrators or participants could use the IETF’s Conference Policy Control Protocol to manipulate the conference policy. The IETF expects to finish the XCON protocols by later this year or early next year.

endors have been working together to offer wider conferencing interoperability. They will probably adopt XCON within the next 12 to 18 months, according to the IETF’s Johnston. In the future, Wainhouse’s Nilssen predicted, companies will embed Web conferencing technology in their workflow applications, such as those used with sales or customer-relationship management. This would let users easily initiate conferences if desirable in conjunction with sales or CRM activities. “I’m bullish,” said Nilssen. “I’m very optimistic about Web conferencing as a technology. I think it will become embedded in the base fabric of how we communicate and conduct business.” However, the way people use Web

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conferencing could affect its marketplace performance. Said eDial’s Petrack, “If you ask people in the enterprise to identify the least productive thing they do, most will respond ‘going to meetings.’ Any system or service that is centered on meetings, rather than collaborative work, is always going to be a frustrating niche product.” ■ David Geer is a freelance technology writer based in Ashtabula, Ohio. Contact him at [email protected].

Editor: Lee Garber, Computer, [email protected]

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17

TECHNOLOGY NEWS

Telecom Carriers Actively Pursue Passive Optical Networks George Lawton

A

s optical networking has become more affordable, it has moved from the network backbone to wide and metropolitan area networks and then to the local loop. To take advantage of this, telecommunications providers have begun experimenting with various fiber-based technologies to find ones that offer high performance at low cost. One of the leading candidates has been touted for years as the wave of the future: passive optical networks. PONs—considered “passive” because the network infrastructure between the carrier backbone and the customer includes no active electronic elements—enable the deployment of relatively inexpensive, high-bandwidth, point-to-multipoint, voice, video, and data networks either to or near customer premises. These networks could be used for Internet access, metropolitan area networks, or corporate LANs. A PON could serve as a first-mile technology for connections between carriers and users. In the short run, proponents foresee PONs competing favorably with cable-modem and DSLbased broadband networks, which also carry voice, video, and data. The three main PON flavors are based on asynchronous transfer mode

(ATM), Ethernet, and the Gigabit PON Encapsulation Method (GEM). Japan has been leading the way with significant Ethernet-based deployments, while US carriers, in their early PON adoption, are focused on ATM. US companies such as BellSouth, Southwestern Bell, and Verizon; Asian providers such as Japan’s NTT; and European carriers such as British Telecom are deploying PONs. However, the technology faces significant challenges to widespread access, such as the cost of deploying the networks and uncertainty about how the market will evolve.

DRIVING DEMAND FOR PON TECHNOLOGY British Telecom made the initial PON trial deployments in the late 1980s. Raynet began selling a PON-based system in 1989, but the technology lost Published by the IEEE Computer Society

traction as carriers moved to higherperformance, active, single-mode fiber approaches, according to Paul Shumate, a PON pioneer and now executive director of the IEEE Lasers and Electro-Optics Society (LEOS). Fiber-optic networks have since become easier to install. In addition, optics’ cost has dropped, making the technology, formerly practical only for telecommunications carriers’ backbones, more feasible for deployment to consumers and companies, said Ed Szurkowski, director of Lucent Technologies’ Optical Data Networks Research Department. For these price-sensitive markets, lower-cost PONs make more sense than traditional active optical networks. And PONs promise much more bandwidth than DSL or cable-modem technology. The higher bandwidth would be particularly useful to established telecommunications providers, who want the new revenue that fast video and data services could generate. These providers are losing voice-related business to cell phones and Internet telephony, said Gary Lee, chair of the PON Forum and president and CEO of FlexLight Networks. However, providers want to offer their customers attractively priced services, and PONs, by eliminating active electronic components, are less expensive than other optical technologies. PONs are also more reliable because they don’t depend on intervening electronics that could fail, and they are easier to upgrade because there are no active electronics to replace. Additionally, regulatory factors are making PONs more attractive investments for telecommunications carriers. The US Federal Communications Commission recently eliminated requirements that let smaller, newer, competing carriers inexpensively use the optical networks that established regional companies build. This has given the regional companies more incentive to invest in fiber, explained Denise Koenig, a spokesperson for telecommunications carrier SBC. February 2005

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Te c h n o l o g y N e w s

International regulations are going even further, noted Craig Easley, chair of the Ethernet in the First Mile Alliance (EFMA), which supports and helps market Ethernet PONs and other Ethernet-based first-mile technologies, including those using active-opticaland copper-based approaches. In Japan and some parts of Europe, he explained, governments offer carriers tax credits covering the cost of building new fiber networks.

HOW PONS WORK The key to PONs is their ability to transmit signals over fiber without using active electronic components. Active optical networks contain electronic components such as regenerators—which convert signals from optical to electronic and then back to optical—and routers. PONs, on the other hand, use only optical components. A PON consists of an optical line termination, a central distribution transceiver at the service provider’s local facilities that serves multiple optical network units. ONUs are transceivers at the user’s home or office. Both OLTs and ONUs convert binary data streams into an optical format that laser beams can carry. When OLTs send a signal to an ONU, the latter converts it into separate video, voice, and data streams. This means the PON doesn’t need the intelligence to do so, which reduces network complexity. OLTs and ONUs can contain components such as analog-digital processors, fiber-optic ports to connect to a PON system, electronic ports to plug into an Ethernet adapter for accessing data from Ethernet systems, software for managing the flow of traffic between the PON system and other networks, and chipsets with lasers for transmitting optical signals. Because multiple ONUs share a single OLT port and optical feeder, the PON system needs a sophisticated time division multiplexing (TDM) algorithm to separate multiple signals on 20

the same fiber so that they don’t interfere with one another. This eliminates the traffic collisions that would cause many applications to fail. PONs use a splitter to divide a single optical signal into several signals identical to the original. The system then passes the signals down fibers to or near individual user premises. Because each node receives the entire original signal, the system uses encryption to enable a node to decode only the part it is supposed to receive. Each node uses its own laser to transmit signals upstream. Some PONs can be configured to change bandwidth allocations to individual ONUs on the fly, depending on users’ needs. This can enable carriers to more fully utilize their systems and also provide bigger users with more bandwidth, a potentially revenuegenerating service.

As fiber becomes more prevalent, PONs become more popular. PON TYPES There are two ways to distinguish PONs: how close they are deployed to customers and the protocol they use to carry data.

FTTN versus FTTP Some telecommunications carriers, such as BellSouth and SBC, are running fiber to the neighborhood (FTTN), to a box near homes or offices, and then over existing high-speed copper wiring to individual premises. Other providers, such as Verizon, are establishing fiber to the premises (FTTP), particularly for new homes or offices that don’t already have copper-wire connections. Building fiber all the way to premises is more expensive than building fiber to a neighborhood. However, because FTTP networks use only fiber, which lasts longer than copper wiring, they promise more long-term reliability and savings, noted analyst Richard Mack

of KMI Research, an optical-networking consultancy.

PON protocols The PON provides the physical layer for transmitting the signals. To carry the data, the systems use technologies such as ATM or Ethernet, which offer various advantages in data-transfer efficiency, redundancy, quality of service, complexity, and cost. ATM and broadband PONs. APONs were the first ATM-based PONs and provide voice and data, but not video, services. They offer speeds of 155 to 622 Mbits per second downstream and 155 Mbps upstream, and support 16 or 32 nodes and dynamic upstream bandwidth allocation. APON deployment is phasing out as carriers move to broadband PON systems, which can handle video. BPON technology is an APON extension that moved the wavelength for sending data and audio from 1,550 to 1,490 nanometers, thereby opening up the 1,550-nm band for video, explained Dave Cleary, vice president of advanced technology at Optical Solutions, a PON equipment manufacturer. Transceiver improvements have provided the increased power and sensitivity required for handling video without significant added cost. Michael Howard, an analyst with Infonetics Research, estimated that 75 percent of PON systems in the US, where most telecommunications carriers already use ATM, are BPON based. Ethernet PONs. EPONs support data rates of 1.244 Gbps in each direction shared among 16 to 256 nodes. The EFMA’s Easley predicted next-generation EPON equipment will support data rates up to 10 Gbps. EPONs are based on the IEEE 802.3ah—Ethernet in the First Mile—standard. The main attraction of Ethernet in PONs is that most companies already use the technology in their corporate networks, said Easley. Howard estimated that 75 percent of PON systems in Asia, where most

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PONS’ CONS The major challenge to PON adoption, particularly for carriers using copper-based networks, is the significant labor- and engineering-related deployment costs, according to the IEEE LEOS’ Shumate. He said these costs have become a more significant adoption barrier in recent years, as competition from broadband providers has made telecommunications carriers want to recover their deployment costs more quickly than in the past. Better integration of components and other manufacturing advances in PON chipsets have reduced costs by making lasers and analog-digital processors less expensive per unit of bandwidth. Vendors are working on integrating all PON-transceiver components into single chipsets, which would significantly reduce systems’ size and cost, noted Armando Pereira, vice president of the Optical Business Unit at Centillium Communications, a provider of broadband network access products

25,000 Houses with FTTP access FTTP subscribers 20,000 Thousands of people

telecommunications carriers don’t use ATM, are Ethernet based. Gigabit PON. GPON supports data rates of 622 Mbps to 2.488 Gbps downstream and up to 2.488 Gbps upstream, shared by 16 to 128 nodes. The higher speeds enable carriers to split the bandwidth to serve a greater number of nodes than APONs or BPONs. According to Howard, industry observers see GPON as the successor to BPON because it is faster and flexible, supporting ATM, Ethernet, and TDM on the same network. With GPON, all services are mapped onto the PON using either ATM or GEM, a variant of Sonet’s (synchronous optical network’s) generic framing procedure. GEM lets a GPON link carry both Ethernet and TDM traffic and also adds QoS and recovery capabilities. Carriers are deploying GPONs throughout the world. Two major GPON equipment manufacturers are FlexLight and Optical Solutions.

15,000

10,000

5,000

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1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Source: KMI Research

Figure 1. KMI Research, a market analysis firm, projects that the number of US homes deploying fiber-to-the-premises networks and the number of homes with FTTP access will grow dramatically during the next few years.

that has already developed an integrated PON chipset. Carriers will face a challenge in learning the most efficient and costeffective way to phase out their old copper networks and phase in PONs, added Lucent’s Szurkowski. Provisioning network services will pose another hurdle for PONs, according to Pereira. He said asymmetric DSL’s success has been largely due to customers’ ability to install their own modems when they subscribe for service. Provisioning fiber-based services, on the other hand, involves different tools and more sophisticated skills than connecting copper wires. nalysts are expecting strong growth for fiber deployments. Infonetics’ Howard said that as the cost of fiber continues to drop and gets close to that of copper, it will make sense to switch to optics. “In 20 to 30 years,” he said, “everything will go to fiber.” KMI projects the number of US homes with access to FTTP-based networks will climb from 2 million in 2004 to 23.5 million in 2009, as Figure

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1 shows. Many of the new fiber deployments will involve PONs. Future wavelength PONs will be based on dense wavelength division multiplexing, a technology that puts data from different sources together on an optical fiber, with each signal carried on its own light wavelength. These PONs, which are still a few years off, would provide a separate wavelength of light for connections to and from each node. Competition from present and future network-access technologies could pose the greatest challenge to PONs’ long-term success, Shumate said. If PONs can’t compete on price, potential users will choose cable, wireless, and other broadband technologies instead.

George Lawton is a freelance technology writer in Brisbane, California. Contact him at [email protected].

Editor: Lee Garber, Computer, [email protected]

February 2005

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NEWS BRIEFS

One-Handed Keyboard Helps Mobile and Disabled Workers company has developed a keyboard designed to be used with one hand. The FrogPad thus could help mobile workers who don’t always have both hands free or disabled people who have the use of only one hand. The 20-key FrogPad, which measures 3.5 × 5.5 inches, was invented by translator Kenzo Tsubai, who cofounded FrogPad Inc. and oversees its R&D. The FrogPad has 15 full-size keys— F, A, R, W, P, O, E, H, T, D, U, I, N, S, and Y—that the company claims cover 86 percent of the English language.

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There are also space, number, symbol, enter, and shift keys. FrogPad researchers also considered other languages’ character frequencies when designing the keyboard. In deciding on the keyboard’s layout, explained CEO Linda Marroquin, researchers incorporated aspects of Dvorak theory, an alternative to the principles behind the traditional QWERTY keyboard (named after the first six keys from the left in the top row of letters), and took into account the ways people naturally use their hands. For example, she noted, FrogPad

FrogPad Inc. has developed a keyboard of the same name that can be used with one hand. The keyboard—designed for use with desktop computers, cell phones, or PDAs— could help mobile workers who don’t always have both hands free or disabled people who have the use of only one hand. FrogPad works with various techniques to give its 20 keys all of the functionality of a traditional keyboard and even that of a 10-key phone or calculator.

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places 86 percent of the alphabet under the middle three fingers. Vowels are placed under the index finger. A switch modifies the keys to give them additional characters and functions, including those of the 10-number keypad used on calculators and phones. FrogPad uses a proprietary algorithm to understand commands produced by pressing multiple keys at the same time or sequentially, Marroquin noted. Also, each key can produce one character on the downstroke and another on the release. These techniques let FrogPad produce many symbols with just 15 character keys. To help users keep track of their work, each key’s color changes to white, green, or yellow depending on which of its available characters it represents at the time. Marroquin claims the FrogPad’s design requires less learning time than QWERTY keyboards. She said studies with college students indicate new users require an average of 10 hours to learn to input 40 words per minute, compared to the 56 hours needed with QWERTY keyboards. FrogPad can be connected for use with PCs, Macs, smart phones, or PDAs, either wirelessly via Bluetooth or via a Universal Serial Bus cable, depending on the product. The keyboard is currently in beta testing for the mobile devices. Currently, Marroquin said, the keyboard is primarily used as an assistive technology for people with disabilities. However, the company says it is actively pursuing other uses. ■

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US Increases Quota for Controversial Visas he US Congress has raised the quota for the controversial H-1B visas, which domestic companies use to hire foreign technology workers, by 20,000. The additional visas are only for foreign employees with US graduate degrees. The Congress granted this one-year increase to the H-1B quota after lobbying by technology companies. Companies received all of the original 65,000 visas allotted for 2005 shortly after 1 October 2004, the first day of the current federal fiscal year. The quota was filled so quickly because companies could apply for the visas up to six months in advance. Chris Bentley, spokesperson for the US Citizenship and Immigration Services Bureau, part of the Department of Homeland Security, said his agency will begin reviewing requests for the 20,000 new visas on 8 March. The US grants H-1B visas to skilled foreign workers, many in the computer-technology field. Under the program, employers must pay foreign workers the prevailing wage for their jobs and show that qualified domestic workers aren’t available. To remain competitive in the global marketplace, proponents say, US companies need H-1B visas to hire the most skilled workers wherever they hail from, especially when there aren’t enough native-born workers and university graduates with math, science, and engineering skills. “Failure to do so would hamper our long-term competitiveness and ultimately cost the country jobs,” argued Jeff Lande, senior vice president of the Information Technology Association of America (ITAA), a trade group for US IT companies. He said the H-1B program doesn’t threaten US workers because visa holders represent a very small percentage of all domestic IT employees. One of the chief lobbying groups for the recent H-1B quota increase was

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Compete America, a coalition that includes the ITAA and companies such as Hewlett-Packard, Microsoft, Motorola, and Texas Instruments. H-1B opponents say some companies favor the visas because they want

to use them to hire foreign workers for lower long-term salaries than they would have to pay equally qualified US workers, said George McClure, a retired engineer and former chair of the IEEE-USA’s Career and Workforce

Disposable Cell Phone Cover Turns into a Sunflower A Bermuda-based company has developed a clip-on cell phone cover that will grow a sunflower when thrown out. This biodegradable cover could ease some of the burden on landfills that cell phones and their accessories create when thrown away and taken to landfills, said Peter Morris, project manager for Pvaxx Research & Development. Pvaxx has been working with Motorola to develop a nontoxic polyvinyl-alcohol plastic polymer that bacteria will consume and that thus biodegrades when discarded into soil. Polymers are typically resistant to bacteria and thus not biodegradable, noted Morris. Researchers at the UK’s University of Warwick figured out how to embed a sunflower seed in the cover. Morris explained about Pvaxx’s covers, “When they decompose, they produce ammonia, then nitrates, then nitrites. This is plant food.” The nitrites serve as fertilizer for the embedded sunflower seed. According to Morris, the polymer material, which could be rigid or flexible depending on the application, could be used for various types of electronics and other products. Pvaxx is licensing its technology to select manufacturers—including Motorola— which plan to begin releasing products using the new material this year.

Pvaxx Research & Development, working with the UK’s University of Warwick, has developed a biodegradable clip-on cell phone cover with a sunflower seed embedded inside. When users throw away the cover, it biodegrades and produces nitrites, which feed the seed and turn it into a sunflower. Biodegradable covers could eliminate some mobile-phone-related waste.

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News Briefs

Policy Committee. The IEEE-USA, which represents the career and public policy interests of the IEEE’s US members, has been a leading H-1B critic. McClure said US technology companies’ hiring of foreign workers also discourages US students from pursuing engineering degrees. During the technology-economy boom of the 1990s, the computer in-

dustry lobbied for higher H-1B quotas. Congress passed the American Competitiveness in the 21st Century Act, which increased the visa cap to 195,000 for fiscal years 2001 through 2003. However, the quota returned to 65,000 for fiscal year 2004. Some businesses said they would cope with lower H-1B caps by outsourcing work to other countries.

Lande said the 20,000 additional H-1B visas will help US companies and thereby save engineering jobs in the long run. McClure, on the other hand, said, “We object to the graduate-student exemption. It’s an end run through the back door to get around the quota. The exemption disproportionately harms American engineers.” ■

Engineers Begin Addressing “Talking Spam” ngineers with Qovia, an Internet telephony management company, have demonstrated the feasibility of sending “talking spam” to thousands of phones and have developed an application designed to eliminate the threat. Experts say spam over Internet telephony, also called SPIT, could become a problem as Internet telephony becomes more popular. To see if the threat was possible, explained Choon Shim, Qovia’s chief technology officer and vice president of engineering, he challenged a research engineer to initiate a SPIT attack using a laptop. “In two hours,” Shim said, “he took down a call server and filled up its voice mail server. This is dangerous.” The use of IP networks—which spammers already know how to exploit—and Internet telephony make it easy and inexpensive to send voice messages directly to many handsets via unsolicited bulk calls or directly to voice mailboxes via unsolicited voice mails. Most Internet telephony systems work with software phones, which spammers can hack into and use for sending out SPIT. Spammers can also develop SPIT transmission code that appears on the network to be an authorized phone. They use the code to send large volumes of unsolicited mail to Internet phones. Qovia engineers wrote software that, in simulations, sent up to 2,000 SPIT messages per minute. For the

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demonstration, Shim said, a spitbot was used to harvest destination addresses. “It was easy because these are normally kept in an unprotected storage location in a call server,” he explained. Engineers then wrote a script using a simple Java Telephony Application Programming Interface (JTAPI) to generate calls. The researchers subsequently developed a prototype application that could keep Internet telephony users safe from SPIT. Blocking SPIT requires more than reading message content or a subject line, as is the case with programs that stop unsolicited e-mail. Qovia’s application identifies SPIT in various ways. For example, it recognizes when a source is sending out many transmissions of a fixed length—indicating the type of prerecorded messages usually found in Internet telephony spam. It also flags multiple messages sent out more quickly than a human could transmit them—indicating the machinegenerated calling frequently used with SPIT. Using TAPI or JTAPI as an interface to control calls, Qovia’s application blocks or filters 95 percent of SPIT, explained Shim, who declined to provide further details. Qovia plans to incorporate the new technology into its Internet telephony security software later this year. Victor Kouznetsov, senior vice president for mobile solutions at security vendor McAfee, said experts haven’t

identified any real-world SPIT cases yet. This is primarily because there aren’t enough Internet telephony users to make SPIT attacks worthwhile, explained senior analyst Joe Laszlo with Jupiter Research, a market-analysis firm. However, Internet telephony usage is increasing rapidly. By the end of 2004, half a million US households used the technology, according to Laszlo. By 2009, Jupiter expects about 12 million US users. Unlike some other cyberthreats, such as viruses and worms, spam is driven by economic incentives, Shim said. It is a cheap and effective marketing tool, he explained. The industry should be careful about SPIT because seven years ago, he noted, some Internet and e-mail experts thought e-mail spam was a dubious threat that would never materialize. ■

Editor: Lee Garber, Computer; [email protected]

News Briefs written by Linda Dailey Paulson, a freelance technology writer based in Ventura, California. Contact her at [email protected].

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COMPUTING PRACTICES

Local Search: The Internet Is the Yellow Pages The proposed Internet-Derived Yellow Pages aggregate, annotate, and certify Web content for use in geographically oriented searching. The IDYP provides a framework for combining Internet-derived content with the trust and fairness that characterize the printed Yellow Pages, still the predominant source of consumer-oriented local information. Marty Himmelstein Long Hill Consulting, LLC

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very day, millions of people use their local newspapers, classified ad circulars, Yellow Pages directories, regional magazines, and the Internet to find information pertaining to the activities of daily life: nearby places, local merchants and services, items for sale, and happenings about town. The Internet is not meeting its potential for delivering this type of geographically oriented information. Sometimes the information that people seek is on the Internet, but the tools for locating it are inadequate. In other cases, our industry has not developed the counterparts to replace traditional delivery methods such as the printed Yellow Pages. The trends that point to the rapid growth of geographically oriented search, known as local search, are unmistakable. The most important predictor of the intensity of an individual’s Internet usage is the availability of a broadband connection. As of early 2004, 55 percent of all US adult Internet users had access to such a connection.1 Further, the number of adult Americans who had broadband Internet connections at home increased 60 percent from the same time in 2003, to 24 percent. Broadband access makes the Internet a pervasive, “always-on information appliance.”2 People with high-speed access do more things on the Internet, and they do them more frequently. The Internet has always been used to support local activities, rang-

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ing from Yellow Pages searches, mapping, and vacation planning to researching products prior to purchasing them in a nearby store. Ubiquitous broadband access will serve to increase users’ expectations for better support for all types of location-based computing. On the search side, a market study of 5,000 online shoppers conducted by TKG and Bizrate. com found that 25 percent of the responders’ searches were for merchants “near my home or work.”3 A recent Forrester Group study found that 65 percent of online shoppers researched a product online before purchasing it offline.4 On the content side, at least 20 percent of Web pages include one or more easily recognizable and unambiguous geographic identifiers, such as a postal address. Many of these Web pages have locally relevant content; Web authors don’t put addresses on pages haphazardly. This content is already on the Internet despite the lack of an overarching mechanism for accessing it. On the revenue side, US businesses spend $22 billion annually on local advertising, $14 billion of which is for the Yellow Pages, but only a sliver is for the Internet. Greg Sterling, managing editor for the Kelsey Group, a research firm that provides Yellow Pages metrics, puts the upper limit of advertisers worldwide who purchase paid search slots on the Internet at 250,000, but few of the slots are for

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local content.5 Contrast this with the more than 12 million small and medium businesses (SMBs) in the US, and another 20 million or so in other developed countries. The predominant market for SMBs is local: 60 percent of businesses in the US report that 75 percent of their customers come from within a 50-mile radius.5

LOCAL SEARCH TODAY AND TOMORROW Local search today is discussed in the context of paid listings—the advertisements that appear near the algorithmically computed, or natural, results search engines return in response to user queries. However, paid listings and their variants are not the bedrock upon which local search will be built. To see why, we only need to examine the original and still predominant local search tool, the printed Yellow Pages. The Yellow Pages have many shortcomings, but they also have two virtues that are indispensable for local search: They are both trustworthy and inclusive—they contain at least minimal information on all businesses. Paid listings do not provide the infrastructure for replicating these core Yellow Pages virtues—in fact, the value of paid listings is that they are the opposite of fair. Rather, to reach the widest audience, paid listings require a stratum of YP-like data beneath them, and the richer that stratum is the better. The challenge for the local search community, then, is to facilitate the creation of this stratum of data. It must create better ways to collect and disseminate geographically oriented information about the activities of daily life. To meet this challenge, local search must supplant both the printed Yellow Pages and the current generation of Internet Yellow Pages (IYP)—a transplanted direct-mail mailing list—as a means for gathering and presenting consumer-oriented business information. In ways that are readily evident, the Internet can furnish richer content than the Yellow Pages, but it cannot yet duplicate its orderliness and fairness. And fairness is the crucible by which local search will be judged. If users don’t trust local search, it won’t matter how much better than the Yellow Pages it is. People won’t depend on it. People use the Yellow Pages occasionally, but they are involved in local activities continually. It is therefore natural for local search to reflect the range of activities in which people participate. For example, much of our local activity has a temporal component. The Internet has the potential to provide access to transient local information more effi-

ciently than older distribution mediums. A definition of local search that encompasses The Internet-Derived its temporal, commercial, and noncommerYellow Pages uses cial aspects is that “local search tells me what the Internet for both is located within 100 miles from here and content distribution what is happening within 100 miles from here.” and content Broadly speaking, there are two sources of aggregation. local content on the Internet. Offline-derived local content originates from other, usually older, sources, but is distributed on the Internet. The IYP is the primary source of offlinederived local content on the Internet. Internet-derived local content is gathered directly from the Internet. While many searches return pages with local content, to date only a few systems have attempted to gather and present content that is specifically relevant for local search. Geosearch, a joint project between Vicinity and Northern Light, was the first large-scale effort to derive local content directly from the Internet. Currently, content aggregators, such as the various city and vacation guides that abound on the Internet, provide some of the best local content. These aggregators have good information for popular categories, such as lodging and restaurants, and they rely on the IYP to fill gaps in their coverage. While they are good sources for some types of content, they do not provide a mechanism for replacing either the print or Internet Yellow Pages. The Internet-Derived Yellow Pages provide a framework for local search that incorporates the trustworthiness associated with the Yellow Pages without jettisoning the potential for distributed, unencumbered content creation that is the Internet’s inherent strength. The IDYP uses the Internet for both content distribution and content aggregation. Aggregation is a more significant challenge than distribution, but one that is not adequately addressed by the local search community. The IDYP’s ken is wider than commerce, but local search’s first requirement is to be a better Yellow Pages.

GEOSPATIAL PROXIMITY SEARCHING All varieties of local search require the ability to find information associated with locations within a given distance of a specified search center, known as geospatial proximity searching. Preparing data sources for proximity searching requires several steps. The first step is to locate text that the geoenabled application can map to a physical location. This step is easy for the IYP because it is a simple structured February 2005

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database with defined meanings for each field. For Internet-derived content, the problem is Geosearch trickier because text with geographic signifitransforms location cance can be anywhere on a page. information in text The second step is to transform a location’s textual designation into physical coordinates documents into a on Earth’s surface. As the “Detecting form that search Geographic Content in Text Documents” engines can use for sidebar describes, the topic of detecting geoefficient proximity graphic content within text documents has generated interest in both the commercial and searching. research sectors. In the developed world, a street or postal address is the most common way to refer to a location, particularly for local search. Geocoding applications attempt to resolve a group of tokens into a pair of geographic coordinates, usually expressed as latitude and longitude. Along with each pair of coordinates, a geocoder also returns a value that represents the quality of the returned geocode. The best geocodes are accurate to within a few meters; less specific coordinates usually refer to the centroid of a larger region. Geocoding databases are large and dynamic, like the street networks they represent. Efficiently processing proximity queries against large data sets, such as a nationwide business directory of 14 million businesses, or the Internet, requires spatial access methods. The basic idea of SAMs is to map a two-dimensional (or n-dimensional) coordinate system—in this case latitude and longitude—onto a single-dimensional coordinate system. By doing so, a region on Earth’s surface can be denoted with a single attribute, a spatial key, instead of the four attributes that are necessary to describe a bounding rectangle: the x and y coordinates of the rectangle’s lower left and upper right corners. Spatial keys are computed as the data set to be geoenabled is being built. In the case of a business directory, the spatial key for each business is stored as an additional field along with other fields for the business. If a search application is indexing unstructured text, it adds the spatial keys as additional terms to the index it builds for the page. Unstructured text, such as Web pages, could require several spatial keys because they may contain several addresses. At search time, to determine the set of businesses or Web pages that satisfy a proximity query, the search application maps the user’s search center and desired search radius to a set of spatial keys that cover the area to be searched. It then adds these spatial keys to the user’s nongeographic query 28

terms so that they can be compared to the precomputed spatial keys stored with the dataset being searched. The search application refers to the user’s nongeographic terms to determine which data items within the radius match the user’s main search criteria. Proximity searching algorithms can order results by distance, so results closer to the search center are listed before those farther away. Ordering is routine for IYP applications, but can be problematic for Web pages because of the potentially large number of pages that may need to be sorted. An example of a paraphrased Geosearch query is: “Return Web pages that are about hot-air balloon rides and which contain postal addresses or telephone numbers within 100 miles of 10 Main Street, Poughkeepsie, NY.”

INTERNET-DERIVED LOCAL CONTENT In 1998, a research group at Vicinity developed a prototype system to geoenable Web content. Vicinity modified the spatial access methods it developed for its IYP and business locator products to work as a software component in conjunction with search applications. In 1999, Vicinity teamed up with Northern Light to broaden its experiment to include the general Web corpus. Microsoft purchased Vicinity in December 2002. Geosearch was publicly available from April 2000 until March 2002 from both Northern Light and Vicinity’s MapBlast property. During this time, Geosearch processed about 300 million distinct Web pages. The experience with Geosearch provided the basis for two observations: • the Internet is already a rich source of local content, and • local information on the Internet possesses certain characteristics that simplify the job of aggregating it. The basic idea of Geosearch is that it transforms location information in text documents into a form that search engines can use for efficient proximity searching. Its first step is to scan documents to recognize text patterns that represent geocodable entities. Geosearch avoids semantic text analysis, preferring to leave the determination of a document’s subject matter to the information analysis algorithms of the search application with which it works. Geosearch relies on the fact that a significant portion of the content that is valuable for local search

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Detecting Geographic Content in Text Documents The topic of detecting geographic content within text documents has generated interest in both the commercial and research sectors.

Commercially available products Google Local (local.google.com) scans Web pages for US and Canadian addresses and North American Numbering Plan telephone numbers. Whereas Geosearch used location purely as a filter, Google adds an extra step of trying to correlate the address information on Web pages with IYP data. Most local search offerings combine IYP data with more indepth content from vertical content aggregators, but so far, Google is the only search engine that uses the Geosearch approach of deriving local content directly from Web pages. One sure way to determine whether a search product obtains local content directly from the Internet is to do an idiosyncratic search for which there is unlikely to be any IYP data. For example, both Geosearch and Google Local return results for “worm composting in Thetford, VT”—others do not. MetaCarta’s Geographic Text Search (www.metacarta.com) is a commercially available product that uses a place-name directory in combination with context-based analysis to determine the presence of geographic content. It will, for example, assign a location to the phrase “three miles south of Kandahar.” GTS is appropriate for corpora that might have geographic content but not the obvious markers of postal addresses or telephone numbers.

Research Content-based searching for location information requires identifying tokens that might have a geographic meaning. Systems that use place-name directories, called gazetteers, need to check the gazetteer for every token in a document. A token that is in the gazetteer must then be disambiguated to see if it really represents a location, and if so, which one. This process can be costly. Systems based on standardized addresses typically look first for postal codes. Tokens that look like postal codes are rare, so few trigger additional work. Then, since the sequence of tokens in an address is rigidly constrained, it is not difficult to determine if a potential postal code is in fact part of an address. Efficiency might not be a concern for some document collections, but it is if the collection is the Internet. Web-A-Where,1 a gazetteer-based system that associates geography with Web content, uses several techniques to resolve ambiguities. Ambiguities are classified as geo/geo (Paris, France or Paris, Texas) or geo/non-geo (Berlin, Germany or Isaiah Berlin). The system also assigns a geographic focus to each page—a locality that a page is in some way “about.” Junyan Ding and coauthors2 analyzed the geographic distribution of hyperlinks to a resource to determine its geographic scope. As expected, their analysis showed that The New York Times has a nationwide geographic scope. However, so does the San Jose Mercury News because readers across the country follow this California newspaper’s technology reports. These authors also estimated a resource’s geographic scope by using a gazetteer to examine its content.

In contrast to Ding and coauthors, Geosearch and Google Local rely on a user-centric approach to determine geographic scope because they allow users to specify the search radius of a query. Kevin McCurley3 discussed using addresses, postal codes, and telephone numbers to discover geographic context. Remco Bouckaert4 demonstrated the potential of using the low-level structure of proximate tokens, such as postal addresses, to perform information extraction tasks.

Organizing Web content for local search With the exception of the work by Dan Bricklin,5 relatively little has been written about organizing existing Web content for local search. Bricklin proposed the small and medium business metadata (SMBmeta) initiative as a way for enterprises to present essential information about themselves consistently on the Web. The idea is to create an XML file at the top level of a domain that contains basic information about the enterprise. Since SMBmeta files have a consistent location, name, and structure across Web sites, search applications can easily find and interpret the files. In a perfect virtual world—a Web presence for all businesses, the willing participation of search engines to promulgate the use of metadata standards, and no spam—the original SMBmeta initiative would offer a simple way to disseminate information about local businesses. In lieu of this, Bricklin proposed the SMBmeta ecosystem, which sketches some control mechanisms that are similar to IDYP’s trusted authorities. Upon request, a registry returns a list of the domains it knows about that have SMBmeta data. A proxy maintains the equivalent of the smbmeta.xml file for domains that do not have their own files. An affirmation authority performs the policing functions. Meeting the IDYP goal of creating an Internet version of the printed Yellow Pages requires leveraging the political and organizational infrastructure of trusted authorities. Rather than replicating the capabilities of the Yellow Pages, SMBmeta’s goal is to help small and medium businesses establish a Web presence. However, the two share the approach of annotating Web content with structured information to make it more accessible for various search applications. References 1. E. Amitay et al., “Web-a-Where: Geotagging Web Content,” Proc. 27th Int’l Conf. Research and Development in Information Retrieval, ACM Press, 2004, pp. 273-280. 2. J. Ding, L. Gravano, and N. Shivakumar, “Computing Geographical Scopes of Web Resources,” Proc. 26th VLDB Conf., Morgan Kaufmann, 2000; www1.cs.columbia.edu/~gravano/Papers/ 2000/vldb00.pdf. 3. K. McCurley, “Geospatial Mapping and Navigation of the Web,” Proc. 10th Int’l Conf. WWW, ACM Press, 2001, pp. 221-229. 4. R. Bouckaert, “Low-Level Information Extraction: A Bayesian Network-Based Approach,” 2002; www-ai.ijs.si/DunjaMladenic/ TextML02/papers/Bouckaert.pdf. 5. D. Bricklin, “The SMBmeta Initiative,” 2004; www.smbmeta.org.

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contains well-formed postal addresses, landline telephone numbers, or both. The presence of one or more addresses is a hint about a document’s subject that the designers of a search application’s relevance ranking algorithms can use as they see fit. One advantage to this approach is that Geosearch is portable. It is a software component that is inserted at a convenient point into a search application’s workflow.

When Web authors include an address, they make an effort, aided by habit, to include one that is well formed.

Address recognizers Geosearch address recognizers detect US-conformant addresses consisting of at least a postal code and a preceding state, Canadian postal codes and a preceding province, and North American Numbering Plan (NANP) telephone numbers (US, Canada, Caribbean). Canadian postal codes are particularly well-suited for local search because they have a short but unique format, and, especially in urban areas, they map to accurate latitudes and longitudes. Geosearch scans all pages for address data. Using brute force to search for US addresses is justified by the fact that such addresses or telephone numbers are found on more than 20 percent of pages. To internationalize Geosearch, it might be necessary to develop heuristics to determine what types of addresses to look for on a page. Address formats vary by country, and searching for an exhaustive set on each page could be too time-consuming. Upon finding an address, the address recognizer forwards what it considers the relevant tokens to the geocoder so that it can assign geographic coordinates to the presumed address. Because geocoding is usually expensive compared to scanning, the address recognizer works to reduce the number of false addresses it sends to the geocoder.

Geosearch observations For the two years that Geosearch was publicly available, and for the preceding year, Vicinity researchers used these techniques to closely observe Internet-derived local search and identify its strengths, weaknesses, and future opportunities. As a large-scale proof of concept, Geosearch exceeded their expectations. Local data permeates the Web. When Vicinity researchers embarked on developing Geosearch in 1998, they evaluated sets of Web pages provided by several popular search engines and portals. On a consistent basis, more than 20 percent of these pages contained either a well-formed US or Canadian address or NANP telephone number. 30

This percentage remained constant for the two years Geosearch was available on the Internet. Although Geosearch only looked for North American addresses, the pages it examined were not restricted to North America. Therefore, the percentage of pages with a well-formed address from some country is certain to be higher than the 20 percent that Geosearch found. Well-formed addresses are the rule, not the exception. The efficiency of the address recognition process was a concern to all of the engineering groups the Vicinity researchers worked with. By requiring a well-formed address, the researchers eliminated fruitless work examining text around tokens that marginally looked like part of an address but were not, such as “Chicago-style pizza.” It turns out that requiring the combination of a state and postal code is not much of a sacrifice. In most cases, addresses on Web pages conform to the postal standards used for the delivery of land mail. Occasionally, a postal code that a group of addresses shared was factored out of individual addresses and placed at the start of a table. Overwhelmingly, however, when Web authors include an address, they make the effort, aided by habit, to include one that is well formed. Thus, by promulgating addressing standards for the efficient delivery of land mail, national postal services have made a major contribution toward geoenabling the Web. If telephone numbers are excluded, Geosearch found at least one address on 15 percent of pages. Some enterprises use a telephone number as the primary contact point. Plumbers, for example, serve a geographic area, and they rely on a phone number rather than a storefront to establish a local presence. A counter example is that customer service phone numbers are probably not interesting for local search. Nationwide customer support numbers, however, are often toll free, and Geosearch did not consider these. Sometimes the address recognizer found a telephone number, but not an accompanying address that was in fact available. In these cases, the presence of a phone number could trigger more intensive scanning of the surrounding text for an address. The basic results were so encouraging, however, that we did not consider additional work on the address recognizer to be a high priority. Addresses are keys to rich exogenous content. For most people, an address provides enough information to build a mental image of a location in a familiar neighborhood or to use as an index for finding the location on a map. An address is not

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directly usable for the distance computations and the mapping and routing applications that location-based computing requires. This is the job of geocoding applications that associate an address with a physical location on Earth’s surface. The databases that these applications use represent significant intellectual capital. For example, the US street network product from Geographic Data Technology, a leading provider of geocoding databases, contains more than 14 million addressed street segments, postal and census boundaries, landmarks, and water features. The company processes more than one million changes for this database each month (www.geographic.com/home/ productsandservices.cfm). An address is the key that associates this rich vein of exogenous information with Web content. Addresses are proportionally more valuable for local search because they are computationally easy to detect. Addresses are metadata. The WWW Consortium defines metadata as machine-understandable information for the Web (www.w3.org/metadata). To date, attempts to incorporate metadata into search engine relevancy metrics have not gone well. HTML metatags are ignored because they are either misused or used fraudulently, and metadata standards have no value if they are disregarded. It’s interesting to envision the semantic Web that metadata enables, but it’s not yet ready for prime time. These concerns are not persuasive for local search. Geosearch works because of the anomalous but fortunate circumstance that the metadata it depends on is already pervasive on the Internet. An address is metadata; its definition predates the Web, but its structure is portable to it. Pages with addresses tend to be good quality. Organizations that put postal addresses on Web pages see the Internet not as a frivolity, but as a way to convey information. Even when a page with an address is unappealing, a quick glance at the site usually leads a user to conclude that the authors don’t know how to create a good Web presence, not that they are swindlers or kids with too much time on their hands. Local search is about more than commerce. Internet content reflects what people do—and they do more than shop: They have hobbies, seek like-minded individuals, look for support in times of stress. Sometimes when people do shop, either from preference or necessity, they are not looking for the closest chain store. They are looking for the practitioner of a local craft—a scrimshaw artist in Nova Scotia—or for some activity that is not quite

mainstream—worm composting or home solar power generation. The data that The individual constituencies for the activcharacterizes the ities people pursue on a daily basis might be Internet Yellow small, but taken together they comprise much Pages is broad, of the regional information people search for. Some of the most satisfying Geosearch results uniform, shallow, were for idiosyncratic local content: breast and slow to change. cancer support groups, bird sightings, firstedition rare books, maple syrup (in Vermont), Washington Irving (in Tarrytown, New York). One hundred years ago the Sears catalog was an innovation for distributing information about mainstream consumer goods. Improvements since then have been around the edges. The overlooked promise of local search is that it makes niche information not routinely found in mail-order or Internet catalogs, the Yellow Pages, or on television or radio, easy to come by. In this it is unrivaled by previous distribution mediums.

OFFLINE-DERIVED LOCAL CONTENT In contrast to Internet-derived local content, the data that characterizes the Internet Yellow Pages is broad, uniform, shallow, and slow to change. This data wends a circuitous route from initial compilation to its final destination in IYP listings. List compilation vendors, whose traditional customers use their products for business mailing lists, sales lead generation, and other direct mail and telemarketing applications, furnish IYP data. The compilers’ main data sources are printed telephone directories, which are converted to digital information with OCR devices. InfoUSA, a leading provider of premium lists, compiles its US list of 14 million businesses from 5,200 phone directories (www.infousa.com). The company augments this phone book data with secondary data sources such as annual reports, SEC filings, business registrations, and postal service change-of-address files. The compilers verify the information they gather by calling businesses. InfoUSA makes 17 million such telephone calls annually. The IYP is slow to incorporate new and changed information, a shortcoming that is inherent in the source of its data, since telephone books are published annually. List vendors do generate periodic update files, but these updates are not free, and the effort required to merge them into the IYP is not trivial. More fundamentally, staying current is an elusive goal for decentralized information that is comFebruary 2005

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piled centrally. Telephone directories are out of date even at the moment of publication. The IDYP is Then, list vendors must correlate changes from their incoming data streams—the 5,200 a directory of local directories, telephone verification calls, businesses, similar change-of-address files, and so forth. Each to the IYP but richer periodic update includes only a fraction of in content. the changes in a vendor’s possession, and it includes no changes that have occurred but are still in the pipeline. Another problem with using compiled lists as a source for the IYP is that the consumer is not its primary market. The lists are flat structures without sufficient expressive power to convey the hierarchical and variable structure of many enterprises, specifically those with multiple external points of contact. This missing information corresponds to some of the most dog-eared pages in printed directories: individual departments and physicians in hospitals and medical practices, group practices of all sorts, and municipal information. Even if this deficiency were somehow fixed, IYP service providers would still need to reflect the richer structure in the online databases they build from the compiled lists. For all their shortcomings, the compiled lists from which the IYP is derived are authoritative and trusted sources of business information—characteristics that are not duplicated elsewhere. The clerks making those calls provide real value. Even if the information in the IYP already exists on the Internet, or will sometime soon, it is in a chaotic form, and there is no repeatedly reliable way to access it. The value of the compiled lists is data aggregation, an area in which local search has not yet contributed.

DECENTRALIZED DATA GATHERING: THE INTERNET-DERIVED YELLOW PAGES The central challenge for local search is to move the job of aggregating and verifying local information closer to the sources of knowledge about that information. The human and electronic knowledge about local information is decentralized—geographically localized—and the Internet is a decentralized medium. Having decentralized tools for gathering this data is desirable as well.

Trusted authorities The IDYP is a directory of local businesses, similar to the IYP but richer in content. The essential difference is that the information in the IDYP is derived directly from the Internet, not from offline sources. 32

The IDYP’s viability depends on intermediaries, trusted authorities who can vouch for the information the IDYP provides and can perform the role of content aggregator for entities without a direct Web presence. Organizations that have relationships of trust with both the public and the entities whose information they are certifying or creating can perform this gatekeeper role. Two examples of organizations that can serve as gatekeepers are those based on geography, such as a chamber of commerce, and those based on market segment, such as a trade organization. A primary function of both types of representative organizations is to collate and disseminate accurate information on behalf of their members. Both types of organizations are often conversant with Web technology, and they can function as proxies for constituents who don’t have their own Web presence. While there are 14 million businesses in the US—most of them small—chambers of commerce and trade organizations number in the thousands. Preventing fraudulent interlopers from compromising the integrity of their constituents’ information is also in the best interests of these gatekeepers. For chambers, this is conceptually and practically as simple as ensuring that each member it verifies or submits to the IDYP does indeed have a shop on Main Street. The first function of a trusted authority is either to submit information to the IDYP on behalf of a member or to certify information a member has directly submitted to the IDYP. The second function, policing, is aimed at minimizing the amount of fraudulent or misleading data that makes its way into the IDYP. Proxy mode. In proxy mode, trusted authorities are intermediaries for members who want a presence in the IDYP but do not want to interact directly with the Internet. For example, a licensed hotdog-stand vendor with no interest in using the Internet would work with a representative at the chamber of commerce to get the right information into the IDYP. A hypothetical entry for this vendor would indicate that the stand is open from two hours before an event until one hour afterwards, provide the stand’s location in the stadium, and state the type and price of the hotdogs, drinks, and condiments he sells. If, at the last minute, the vendor finds he will not be at an event, he can ask his contact to update his IDYP entry. This example is contrived, of course—but try finding information on street vendors in the Yellow Pages. Authenticate mode. A trusted authority uses a Web

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interface to help create the structured information the IDYP requires for the members under its purview. The trusted authority releases this information to an IDYP server, at which point it becomes generally available. An entity can directly submit information to an IDYP server as long as the submittal refers to at least one valid registration with at least one trusted authority.

Policing Unlike a purely virtual search, the subject matter in local search has a physical existence that can be confirmed. Therefore, local search is more resistant to fraud than are purely virtual searches. In the IDYP model, if no trusted authorities vouch for a business, it will not be included in the IDYP. Still, we must assume that efforts will be made to game the system and that some businesses will be tempted to misrepresent themselves. The Internet’s potential to provide assurances about local enterprises exceeds that of current directory services. It isn’t possible to rely on the Yellow Pages to provide guidance about a business’s reputation. The IDYP, however, can augment its information with various data sources, such as Better Business Bureaus, independent reviews, and public data. In addition, the IDYP can use practices that have become popular on the Internet for rating products, services, and sellers.

IDYP OPERATION MODES Geosearch found that at least 20 percent of Web pages include an overt geographic qualifier. Even if every local enterprise eventually registers with a trusted authority, the Web will still contain much local content that is not known to the IDYP. Geosearch’s strength is that it finds local content in place, without requiring Web authors to change their routines for publishing that content. To integrate its content with local content on the Web that is not part of the IDYP, the IDYP supports two modes of operation. In one mode it supplies local search metadata to authorized applications; in the other, it is a stand-alone directory application.

Local search metadata In the local search metadata mode, the IDYP makes its content available to subscribing applications. Subscribers are bound to use IDYP data in conformance with the policies and standards the IDYP sets forth. Trusted authorities and individual businesses can also specify directives on how subscribers use their information. As a part of the page indexing process, a sub-

scribing search application seeks associated IDYP information for the page it is indexing. In the IDYP model, If the page is authorized for local search, the if no trusted search application includes some portion of the IDYP metadata in the index it builds for authorities vouch the page. In this way, IDYP data is incorpofor a business, rated into the general Web corpus. it will not be A URL provides the connection between included in IDYP data and data on the Web. When an the IDYP. enterprise or its trusted authority creates its IDYP entry, it specifies a Web page address with which the IDYP entry is associated. This is the page to which the search application adds the IDYP metadata. For a member who doesn’t have a direct Web presence, the trusted authority creates one or more pages that contain formatted content derived from the member’s IDYP entry. The trusted authority either establishes a domain for the member or guarantees that the pages it creates for the member have persistent URLs. A trusted authority might choose to generate pages for all its members. This would allow it to establish a consistent look and feel for its constituents. IDYP pages generated for members that already have established Web sites would contain links back to these existing pages. The IDYP provides an imprimatur for pages that are relevant for local search. To accommodate pages with local content unknown to the IDYP, search applications can support either strict or nonstrict local searches. In strict mode, the search application only considers pages that are known to the IDYP. In nonstrict mode, the search application uses its own heuristics for gauging which pages are relevant, and can return a mixed set of pages, some known to the IDYP, some not. If the search application tags the results that are known to the IDYP, users can decide for themselves how important the IDYP imprimatur is. It will be more valuable for Yellow Pageslike searches, less so for idiosyncratic ones.

Stand-alone local directory Given the popularity of search engines and portals as user interfaces, observers might anticipate that the IDYP’s main role is to provide metadata for these applications. However, as a self-contained local directory, the IDYP can provide powerful features that are difficult to incorporate into a generalpurpose search engine. Important, too, is that the IDYP should not depend on any particular search application for its promulgation. Its status as a stand-alone application ensures its independence. February 2005

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Standard data representation. IDYP information is represented in XML. In addition to a standard core of attributes, industry groups can define customized extensions—known as XML schemas. An “hours of operation” attribute, for example, is part of the standard core, since virtually all businesses use it—although today’s IYP does not include even this basic information. The XML Schema for restaurants should allow queries about the catch of the day at the local seafood house. Rich categorization hierarchy. The business categorization schemes used by the print and Internet Yellow Pages are cursory. The Internet has spawned much work on commerce-oriented ontologies and user interfaces that are broadly applicable to local search. Local search query language. A rich stratum of

metadata will facilitate the construction of a local search query language with more expressive power than the Boolean keyword languages that current search engines use. The parlance of local search is constrained—a variation of who, what, where, when, and how much: Who provides what service or product? Where is the provider located? When can I see the product? How much does it cost? For example: “Where can I buy stylish children’s clothing on sale, within 10 miles of home, open late on Saturday evening?” Short update latency. The time interval between an enterprise making a change and having that change reflected in the IDYP is brief, converging on instantaneous. We can define “the last croissant” heuristic, which states that the IDYP reaches optimal efficiency when an urban bakery can use it successfully to advertise a sale on its remaining bakery items 30 minutes before closing.

References

G

Acknowledgments The author thanks the many people involved with making Geosearch happen, including the following—from Vicinity: Jeff Doyle, Charlie Goldensher, Jerry Halstead, Dwight Aspinwall, Dave Goldberg, Faith Alexandre, Darius Martin, Kavita Desai, and Eric Gottesman; and from Northern Light: Marc Krellenstein, Mike Mulligan, Sharon Kass, and Margo Rowley.

eosearch, a geoenabled search engine that allows people to search for Web pages that contain geographic markers within a specified geographic area, demonstrates that the Internet is a rich source of local content. It also demonstrates the many advantages that postal addresses have as a key for accessing this content, especially when the content pertains to the activities of daily life. Postal addresses are ubiquitous, unambiguous, standardized, computationally easy to detect, and necessary for accessing the rich and precise content of geocoding databases. The Internet Yellow Pages, currently the main source of local content on the Internet, are reliable, but they are also shallow, slow to change, centralized, and expensive. Their primary data sources are 34

printed telephone directories. They do not use the Internet’s resources in any meaningful way. Local search today provides a poor user experience because it does little more than package old data for a new medium. The richest source of local content can and should be the Internet itself, but marshaling this resource requires developing an infrastructure such as the Internet-Derived Yellow Pages to organize and manage its content. The IDYP is a structured database that relies on trusted authorities, such as chambers of commerce or trade associations, to certify the information it contains. The IDYP can function either as a standalone directory or as a source of metadata for search applications. A search application uses IDYP metadata to augment the information it maintains for Web pages that have local content. In this way, local search metadata is integrated into the general Web corpus. ■

1. J. Horrigan, Pew Internet Project, “Pew Internet Project Data Memo,” Apr. 2004; www.pewinternet. org/pdfs/PIP_Broadband04.DataMemo.pdf. 2. J. Horrigan, L. Rainie, Pew Internet Project, “The Broadband Difference,” June 2002; www.pewinternet. org/pdfs/PIP_Broadband_Report.pdf. 3. Kelsey Group & Bizrate.com, “Local Search Now 25% of Internet Commercial Activity,” Feb. 2004; www.kelseygroup.com/press/pr040211.htm. 4. S. Kerner, “Majority of US Consumers Research Online, Buy Offline,” Oct. 2004; www.clickz.com/ stats/markets/retailing/article.php/3418001. 5. G. Sterling, “Is 2004 the Year of Local Search?” Dec. 2003; www.imediaconnection.com/content/2343.asp.

Marty Himmelstein is a software consultant. His interests include database systems, spatial databases, and Web technologies. He received an MS in computer science from SUNY Binghamton. He is a member of the IEEE Computer Society and the ACM. Contact him at [email protected].

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GUEST EDITOR’S INTRODUCTION

Nanoscale Design & Test Challenges The silicon-scaling revolution presents a plethora of challenges as technology progresses into the nanoscale era. To meet these challenges, the design and test community has banded together to improve design automation and find solutions that will optimize performance at every level.

Yervant Zorian Virage Logic Corp.

36

T

he silicon-scaling revolution is quite real and persistent. As we move to each new technology node, we attain a 50 percent area reduction and a 30 percent performance increase. The continuous scaling presents a plethora of design challenges as we progress into the nanoscale era, which imposes the need for additional design processes, such as design for manufacturability and power management, and introduces much higher mask and tooling costs. Moreover, the bizarre vagaries of nanoscale technologies put a heavy burden on the test community, as scaling beyond 90 nanometers greatly extends process complexity and exacerbates leakage faults and soft errors. At the same time, process variants include new dielectrics, multiple oxide and metal layers, multiple voltage thresholds, and smaller noise margins, so that a product engineer faces serious yield implications. The increasing number of available transistors is leading designers to incorporate even more on-chip functionality in the form of large embedded memories, base I/Os, and a variety of signal and protocol processing blocks. This is far outpacing designer productivity and is greatly increasing design complexity. Finally, with fabs expected to cost on the

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order of $3.5 billion and with skyrocketing reticle costs, successful companies must ship in high volumes with increased yields and amortize their design costs over multiple product lines by adopting, integrating, and reusing silicon-aware intellectual property blocks from qualified vendors. To this end, the design community is working together to further design automation and improve design flows—be it silicon-aware IP design and delivery or hardware and software automation that lets designers work with higher-level languages and abstractions that hide the underlying process complexities and allow performance, power, and area optimization at every level. Similarly, the test community is looking beyond bolt-on test approaches to solutions such as infrastructure IP for embedded test, diagnosis, and repair. To maximize manufacturing yield, the infrastructure IP functions must be optimally tuned to the design under test.

DESIGN AND TEST COMMUNITY To face these challenges, the design and test community has organized itself into several professional and business-oriented organizations. As the “Test Technology Technical Council” sidebar describes, the TTTC, a professional organization

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sponsored by the IEEE Computer Society, serves the worldwide test community with a wide range of activities, including educational programs, conferences, workshops, and standards. The EDA Consortium is a business-oriented organization that represents 100 electronic design automation companies. The consortium seeks to identify and address issues that are common among these companies and the customer community they serve. By focusing on commonality and promoting cooperation, the consortium augments the effectiveness of design automation tools and services. Established in 1994, the Fabless Semiconductor Association serves the design and test community by supporting the ongoing, symbiotic relationship between fabless semiconductor companies and their suppliers, including semiconductor foundries, IP providers, electronic design automation vendors, and design service houses. The FSA facilitates productive business partnerships, disseminates relevant data, and promotes the growth of the fabless business model. These vibrant organizations are working together to address the many challenges that face the industry as we move to 90 nanometers and below. We are proud to be associated with Computer’s Nanoscale Design & Test issue showcasing some of the exciting ideas that keep our industry ahead of Moore’s law.

IN THIS ISSUE This issue features three articles describing various advanced aspects of design and test. In “Robust System Design with Built-in SoftError Resilience,” Subhasish Mitra and colleagues address the increasingly prevalent problem of soft errors or single-event upsets. Transient errors caused by terrestrial radiation pose a major barrier to robust system design, especially as chip sizes shrink and system susceptibility to error increases. The authors describe a number of soft-error protection techniques, including a strategy for using on-chip scan design-for-testability resources for soft-error protection during normal operation. “Transistor-Level Optimization of Digital Designs with Flex Cells” by Rob Roy and colleagues explores another extremely important subject: the increasing need to reuse IP in today’s chip designs. The use of precharacterized and siliconverified standard cells is driven by the need to create and verify large digital circuits without having to verify the circuit’s behavior at the transistor level, which is simply too resource intensive to be commercially viable for most designs. On the other

hand, the quality of such automated standard-cellbased designs has been poor at best, running slower by a factor of 6 and consuming more area by a factor of 10. The quest to overcome these limitations leads naturally to the creation of new designand context-specific cells—designated flex cells— during the process of optimizing a given digital design. Designers then use these cells via a combination of register-transfer-level coding style and synthesis directives. Finally, the technical evolution we are witnessing today—particularly shrinking geometries—is enabling the integration of complex platforms in a single system on chip, and SoCs with more than 100 processors could become commonplace. Compared with conventional ASIC design, such a multiprocessor SoC requires a fundamental change in chip design. In “Hardware/Software Interface Codesign for Embedded Systems,” Ahmed A. Jerraya and Wayne Wolf propose an interfacebased HW/SW codesign methodology that takes advantage of IP blocks. Working at higher levels of abstraction, the productivity of a designer who can generate only 100 lines of Hardware Description Language code per day is higher if those lines rep-

Test Technology Technical Council The Test Technology Technical Council is a volunteer professional organization sponsored by the IEEE Computer Society. The TTTC’s goals are to contribute to the professional advancement of the test community, help its members solve engineering problems in electronic test, and help advance the state of the art in test technology. Through its more than 30 sponsored conferences and workshops, the TTTC serves as the primary source of knowledge about electronic test. Other TTTC efforts include its worldwide test technology educational program (TTEP); five geographically distributed regional groups; and a Web site, newsletter, and electronic broadcasts. The TTTC is actively involved in identifying emerging topic areas in test technology. It initiates corresponding technical committees and nurtures the creation, adoption, and implementation of standards. Emerging topics that the TTTC currently covers include defect-based testing; debug and diagnosis; infrastructure IP; testing of FPGAs, memories, analog, and microprocessors; and test technology for embedded cores, boards, and system-on-chip, system-in-package, and electronic systems. TTTC membership is open to all individuals directly or indirectly involved in test technology at a professional level. TTTC members pay no dues or fees. To learn more about TTTC offerings and membership benefits, visit http://tab.computer.org/tttc.

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Signature Conferences Three signature conferences serve the global design and test community.

Design, Automation, and Test in Europe As the most comprehensive European conference and exhibition event, DATE brings together academic researchers, industry specialists, users, and vendors in the fields of design, automation, and test of electronic circuits and embedded systems. The endless quest for faster, cheaper, and safer electronic products that consume less power—particularly for the growing consumer and communications markets—dictates generating increasingly complex designs in continually shrinking time scales. Design automation is a strategic technology for modern electronic systems, ranging from simple ASICs via embedded IP cores to large systems on chip made of heterogeneous processors communicating via on-chip networks. Testing these complex electronic systems is becoming a key factor in enabling the final quality goals, and it has an increasing impact on the overall cost of product development. In addition to the regular paper sessions, DATE organizes interactive presentations for novel “ongoing work,” offers a Designers’ Forum devoted to the specific needs of designers, and provides a complete embedded software track. DATE’s educational day consists of tutorials and master courses. Five workshops follow the conference’s conclusion. A PCB Symposium, fringe meetings, a University Booth, and social events during the conference offer a wide variety of opportunities to exchange information about relevant issues for the design, automation, and test communities. Special themes for DATE 05, scheduled for 7-11 March 2005 in Munich, are dedicated to automotive electronics and biochips. The Executive Track, initiated for the first time in 2004, offers presentations by CEOs, CTOs, VPs, and other senior executives from EDA and semiconductor and system houses. Focusing on business and industry, a presentation theater located on the exhibition floor offers visitors and conference delegates a fresh view of economics, European strength in the industry, and challenges in the current electronic systems design market.

International Test Conference The world’s premier conference dedicated to electronic test, ITC offers design and test professionals the opportunity

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to confront the challenges the industry faces and learn how academia, design tool and equipment suppliers, designers, and test engineers are combining their efforts to address these challenges. As the cornerstone of Test Week, ITC offers a wide variety of technical activities targeted at test and design theoreticians and practitioners, including formal paper sessions, tutorials, panel sessions, case studies, lecture and application series, commercial exhibits and presentations, and a host of ancillary professional meetings. Some of the conference’s most significant papers are now available online. With the theme “Test: Survival of the Fittest,” the 2005 conference will focus on evolving new “out-of-the-box” ideas to meet the tough test challenges presented by very-deep-submicron technologies and the competition for dominance among alternative solutions. ITC 2005 will be held 8-10 November in Austin, Texas; www. itctestweek.org.

IEEE VLSI Test Symposium The IEEE VLSI Test Symposium (VTS) explores emerging trends and novel concepts in testing, circuits, and systems. The three-day technical sessions respond to the many trends and challenges in the semiconductor design and manufacturing industries, featuring papers covering design validation, debug, test, repair, failure analysis, and fault tolerance for embedded IP cores, chips, boards, and systems. In addition to the technical sessions, VTS features two keynote addresses, panels, embedded tutorials, hot topic sessions, and an Innovative Practices track. This track highlights the cuttingedge challenges that test practitioners face and explores the innovative solutions employed to address them. The VTS program addresses a wide range of interests, including basic and continuing education for test professionals, the latest research developments, new directions and hot topics in test technology, and expert perspectives on current issues. Full-day tutorials and two full-day workshops are also held in conjunction with VTS. The tutorials are part of the Test Technology Education Program. In addition, VTS hosts a number of standardization Working Groups and IEEE Fringe Meetings. An exciting social program at VTS provides an opportunity for informal technical discussions among participants. VTS is sponsored by the TTTC and will take place 1-5 May 2005 in Palm Springs, Calif.; www. tttc-vts.org/public_html/VTS05_CFP.pdf.

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IEEE P1500 Standard for Embedded Core Test The IEEE Computer Society’s Test Technology Technical Council initiated IEEE Embedded Core Test P1500 Standard for Embedded Core Test (SECT) in 1995 as a Technical Activities Committee to identify the common needs in the system-on-chip test domain. In 1997, the IEEE Standards Board granted permission to start the IEEE P1500 standards activity. In January 2005, IEEE P1500 went through a successful recirculation. Since its inception, P1500 has focused on the critical aspects of ease of reuse and interoperability with respect to testing when IP cores originating from distinct core providers come together in one SoC. P1500 standardizes core test information, model transfer, and test access for embedded cores, concentrating on areas that are at the interface between core provider and core user. As a scalable standard, IEEE P1500 contributes to ease of plug-and-play for testing, while maintaining the required flexibility to cope with different cores and system chips. Leading volunteer experts in relevant industry segments, such as systems companies, EDA vendors, core providers, IC manufacturers, and automated test equipment suppliers, have IEEE

P1500

actively participated in developing IEEE P1500. The first version of the standard focuses on nonmerged digital logic and memory cores. In future extensions, P1500 will cover analog and mixed-signal cores, as well as the design-for-test guidelines for mergeable cores. The two main elements of the IEEE P1500 standard are a scalable core test architecture and an information model. For the scalable architecture, P1500 does not standardize test pattern sources, sinks, or test access mechanisms—that is, the test access “highway” from source to core to sink. With respect to test access for embedded cores, P1500 only standardizes the test wrapper around the core and its interface to one or more test access mechanisms. The information model is meant to standardize the core test knowledge transfer. The P1500 information model is based on IEEE P1450.6, a standard initiated to accommodate specific core test constructs. The IEEE P1450.6 Working Group collaborates to provide the necessary language for P1500 core test knowledge transfer. For additional information about this hot topic, visit the P1500 Web site: http://grouper.ieee.org/groups/1500.

IEEE Design & Test of Computers IEEE D&T, a bimonthly magazine copublished by the IEEE Computer Society and the IEEE Circuits and Systems Society, is specifically directed to design and test engineers and researchers. D&T features peer-reviewed original work describing methods and practices used to design and test electronic product hardware and supportive software as well as design automation tools and methodologies. D&T publishes tutorials, perspectives, roundtable discussions, viewpoints, conference reports, panel summaries, and standards updates contributed by authors working in the industry. Paper submission: Submit manuscripts for peer review to

resent large blocks rather than logic gates. The ultimate goal of this methodology is to design both hardware and software at all abstraction levels.

hese three articles address only a limited subset of the challenges facing the design and test community. The community regularly conducts conferences, workshops, symposia, and forums offering opportunities to explore potential solutions to these challenges. As the accompanying sidebars describe, key examples of these opportunities include conferences like Design, Automation, and Test in Europe (DATE), cosponsored by the TTTC and EDAC; the International Test Conference (ITC) and VLSI Test Symposium (VTS), both cosponsored by the TTTC; publica-

T

D&T at [email protected]. Each submitted paper undergoes at least three technical reviews. All submissions must be original, previously unpublished work. The theme issues for 2005 are Design & Test Methodologies for Scaled Technologies, Configurable Computing, Design for Manufacturability, Nanotechnology, Multiprocessor SoCs and Networks on Chip, and 3D Integration. Subscription: IEEE D&T offers full-year and half-year subscriptions for print issues. In addition, it offers electronic subscription options to IEEE CS and CAS members, with full-text searchable access to all issues from 1995 forward. Visit D&T’s Web page to access tables of content and article abstracts online at no cost: http://www.computer.org/dt.

tions such as IEEE Design & Test of Computers; and numerous standards, such as IEEE P1500. You are encouraged to further explore the exciting challenges in nanoscale design and test by participating in these events or by subscribing to D&T. ■ Yervant Zorian is vice president and chief scientist of Virage Logic. He received an MSc in computer engineering from the University of Southern California and a PhD in electrical engineering from McGill University. Zorian also received an executive MBA from the Wharton School of the University of Pennsylvania. He is an IEEE Fellow, serves as IEEE Computer Society Vice President for Conferences & Tutorials, and is the editor in chief emeritus of IEEE Design & Test of Computers. Contact him at [email protected]. February 2005

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COVER FEATURE

Robust System Design with Built-In Soft-Error Resilience Transient errors caused by terrestrial radiation pose a major barrier to robust system design. A system’s susceptibility to such errors increases in advanced technologies, making the incorporation of effective protection mechanisms into chip designs essential. A new design paradigm reuses design-for-testability and debug resources to eliminate such errors.

Subhasish Mitra Norbert Seifert Ming Zhang Quan Shi Kee Sup Kim Intel

0018-9162/05/$20.00 © 2005 IEEE

S

oft errors, also called single-event upsets (SEUs), are radiation-induced transient errors caused by neutrons from cosmic rays and alpha particles from packaging material. Traditionally, soft errors were regarded as a major concern only for space applications. Yet, for designs manufactured at advanced technology nodes—such as 90 nm, 65 nm, and onward—system-level soft errors are much more frequent than in the previous generations. Further, customers demand stringent limits on soft-error rates for enterprise servers and networking hardware. All these chips, sometimes hundreds or thousands of them, must operate correctly, with very high system data integrity and availability. An IT executive quoted in Forbes Magazine1 expressed how customers feel when the hardware fails to meet expectations: “It’s ridiculous. I’ve got a $300,000 server that doesn’t work. The thing should be bulletproof.” That is why digital-system soft errors have received significant attention.1,2 The soft-error rate of a system generally is measured in units of Failures in Time, or FIT. A softerror rate of 1 FIT means that the mean time before an error occurs is a billion device hours. IBM sets its target for undetected errors caused by SEUs at 114 FITs,3 which would require a mean time before

an SEU causes an undetected error of roughly 1,000 years. The high data-integrity and availability requirements for servers and networks4 make soft errors an extremely important design aspect for microprocessors, network processors, high-end routers, and network storage components. Thus, soft-error protection is just as important as other product characteristics such as performance, power consumption, yield, and test quality. Chip designers must address soft errors very early, starting from the product definition phase and continuing through the architecture planning, circuit design, logic design, and postlayout phases. Designers routinely use well-known techniques such as error detection and correction to cope with soft errors in static random access memory. Protecting SRAMs isn’t enough, however, given the soft-error rates and customer expectations. Designers must evaluate the effects of soft errors in flip-flops, latches, and combinational logic, and effective protection mechanisms must be incorporated into the design.

SYSTEM-LEVEL SOFT-ERROR-RATE ESTIMATION The soft-error rate (SER) of a design can be expressed in terms of the nominal soft-error rates of individual elements such as SRAMs, sequential ele-

Published by the IEEE Computer Society

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Soft-Error Testing: Key Points Michael Nicolaidis and Damien Chardonnereau, iRoC Technologies Following a strategy similar to traditional burn-in for generalreliability purposes, soft-error testing seeks to reproduce and then accelerate the die’s real-life environment. Researchers use a neutron beam accelerator and alpha foils to conduct this testing. Because each neutron beam has a specific and complex set of neutron properties, the beams must be carefully qualified to correlate the resulting data with real-time results. Beam qualification includes factors such as energy, spectrum, fluency, and tail-effect correction. Likewise, the actual die tester also must be specifically designed for portability, ruggedness, flexibility, and dynamic testing. These issues and the effort required to access a neutron beam facility have prompted many companies to outsource this work to a soft-error test consolidator. Doing so gives companies more test-schedule flexibility, lowers the total costs of soft-error testing, and strengthens their SER data value through test independence.

Environmental acceleration Real-time testing offers another means for accurate soft-error rate detection. However, given that neither single-event upsets nor soft-error-induced latch-ups occur frequently, testers employ environmental acceleration, such as testing at high altitudes where the neutrons’ flux is stronger while the spectrum remains equal to that at ground level. Table A shows the advantages of accelerated testing over real-time testing. Consider, for example, the Jungfraujoch lab in Switzerland. Located at 11,000 feet, the facility can accelerate sea-level test times by a factor of 11. In testing conducted at this lab, iRoC Technologies obtained a statistically significant number of soft errors on different devices over a period of 4 to 6 months. This test for soft-error rates covers all different phenomena, including multibit upsets.

ence SER, which is statistical in nature. As processes migrate to nanometer scale, the reduction in activation energies and the increased amount of embedded memory will cause soft errors to become an issue that designers must deal with. Even as the per-unit FIT rate stabilizes with advanced processes, system-level soft errors have been increasing. iRoC Technologies has performed more than 1,000 SER analyses on different process nodes and devices. This work has revealed a clear trend for SRAM/CAM: The average FIT per megabyte slightly decreases at each process node, through to 130 nm. From that point down to 90 nm, the FIT per megabyte begins to stabilize. Even with stabilization, however, researchers must consider three additional trends: • Several neutron-induced latch-ups have been observed in nanometer memory devices. • Multibit upsets have been observed more frequently. • SEU-rate dispersion becomes more significant at 90 nm than at 130 nm, indicating that SER is both a fixed element driven by a process and an element affected by design methodology. Silicon test results show that the average soft-error rate hovers around 1,000 FIT per megabit (neutron + alpha). The small expected FIT-per-megabit decrease per process node will not counteract the significant amount of memories designers expect to embed in future SoCs. In addition, as designs move to newer nodes, the logic elements in the design will become more sensitive. Techniques must be put into place that will ensure developers take this new sensitivity into consideration.

Michael Nicolaidis is a cofounder of iRoC Technologies and the company’s chief technology officer.

SER trends Predicting the soft-error rate and its impact on a specific die has always challenged physics experts. Many parameters influ-

Damien Chardonnereau is a project leader and product manager for iRoC Technologies.

Table A. Accelerated testing versus real-time testing. Test type

Logistics

Time

Accuracy

Devices under test

Accelerated

Complex: Requires qualified beams access; expert team required Reasonable

Average: 2 to 3 months

Good

Average: 4 to 6 months

Excellent

Memories, SoC, FPGA systems level All types

Real-time

ments such as flip-flops and latches, combinational logic, and factors that depend on the circuit design and the microarchitecture,5,6 as follows: SERdesign = ∑ SER nominal × i i

(Probability error in ith circuit element produces system-level error) 44

In this expression, SERnominal refers to the soft-error i rate of the ith circuit element—for example, an SRAM cell, flip-flop, or latch—under static conditions when all inputs and outputs of the element are constant, independent of the system that uses the element. The SERnominal term is generally estimated using i radiation testing and circuit simulation tools. The

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CLK

Probability error in ith element produces system-level error = TVFi × AVFi The TVF of circuit element i, TVFi, also called the timing derating,5 is defined as the fraction of time the element is susceptible to SEUs that will cause an error in that element. For example, consider the simple D-latch in Figure 1. When the clock input of the D-latch is 1, the upstream combinational logic drives the latch’s Dinput and writes the corresponding logic value into the latch. During this time, any SEU that affects the transistors inside the latch has a negligible effect because the correct value is being driven at the D-input. However, when the clock input of the D-latch is 0, an SEU affecting transistors, such as those with drains connected to nodes S and F, can flip the latch content. Thus, the latch is susceptible to an SEU that can cause an error during the fraction of the total clock period for which the clock signal is 0, which is the TVF of this latch. If the clock duty cycle is 50 percent for a flip-flopbased design, the TVF of an individual D-latch inside a flip-flop is 50 percent. A latch’s TVF can be less than 50 percent, however.6 The TVFs of SRAMs are very close to 1. A glitch induced in the static combinational logic

S

F Q

D

“Soft-Error Testing: Key Points” sidebar provides more details about these calibrations. The timing vulnerability factor (TVFi) and architectural vulnerability factor (AVFi) of circuit element i determine the probability component in the preceding expression, as follows:

Figure 1. A D-latch. When the clock (CLK) input is 0, a single-event upset affecting transistors, such as those with drains connected to nodes S and F, can flip the D-latch’s content, causing an error.

by an SEU must arrive at the destination sequential element within its setup and hold time window to create an error in that sequential element. The TVF of combinational logic is impacted by the clock speed and number of gates located between the node where the glitch is induced and the destination sequential element. Since the setup time and hold times of a sequential element are independent of the clock speed, the TVF of static combinational logic increases with increasing clock frequency. The architectural vulnerability factor of the ith circuit element, AVFi, also called logic derating,5 is the probability that an error in an element results in a system-level undetected error. AVF values depend on the design’s architecture and input stimulus. Consider the following two simple examples. First, suppose that a flip-flop’s content is erroneous. However, if the flip-flop output is ANDed with another signal whose logic value is 0, the error will have no effect. Second, suppose that an error affects a register holding the operand of an instruction in a microprocessor with speculative execution. If this instruction is executed speculatively and becomes a dead instruction later, this error will not affect the results produced by the program the microprocessor executes. Table 1 summarizes various AVF estimation approaches.

Table 1. Architectural-vulnerability-factor (AVF) estimation approaches. Approach Manual

Description

Major issues –

Fault injection 7,8

Inject error(s) and simulate to see if injected error(s) causes systemlevel error(s) by comparing the system response with simulated fault-free response

Fault-free simulation5,9

Perform architectural or logic simulation and identify situations that do not contribute to systemlevel errors, such as unused variables and dead instructions

• No systematic analysis

• What inputs to simulate • How many errors to inject • Which signals to inject errors to • Which signals to use for comparison • What inputs to simulate • How to identify situations that do not contribute to system-level errors

Advantages –

• Applicable to any design • Easy automation

• Much faster compared to fault injection • Easy automation

Disadvantages • Subjective, error-prone, time-consuming, difficult quantitative justification • Long simulation time (several days or weeks) for statistically significant results • Dependence on chosen stimuli • Applicable to very specific designs and not general enough • Dependence on chosen stimuli

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Figure 2. Contributions to the overall soft-error rate for a design manufactured using state-of-the-art technology.

Static combinational logic 11% Unprotected SRAM 40%

Sequential elements 49%

Figure 2 shows the estimated soft-error-rate contributions of various elements for typical designs such as microprocessors, network processors, and network storage controllers. This analysis includes both the TVFs and AVFs of the individual elements. The soft-error-rate contribution of combinational logic for state-of-the-art processes is still considerably smaller compared to the contributions of unprotected SRAMs and sequential elements such as latches and flip-flops. Designers routinely use parity or error-correcting codes (ECC) to protect large memories and register files. For applications requiring high data integrity and availability, the unprotected memories usually represent a small percentage of total memory bits. These memories are composed of small memory arrays for which parity or ECC is useful, but expensive.

For the design used in Figure 2, the combined soft-error-rate contribution of sequential elements and combinational logic exceeds that of the unprotected SRAMs. Hence, special attention is required to develop techniques for protecting nonSRAM portions of a design from soft errors.

TECHNOLOGY TRENDS Several experimental and theoretical studies have demonstrated that the nominal soft-error rate of an SRAM bit, built with state-of-the-art processes, has been saturating or even decreasing for both bulk CMOS and SOI technologies.10,11 For latches and flip-flops, available data in the literature shows less consistency than that for SRAMs. Robert Baumann11 observed that the nominal soft-error rates of sequential elements increase with technology scaling. At Intel, however, we have observed a different trend for some of our latches. The nominal soft-error rates for some latches are fairly constant or even decreasing slightly for the 130-nm to 65-nm technologies.10 The AVFs and TVFs do not change significantly with technology generations.6 As Figure 2 shows,

Soft-Error Protection: Test Results Michael Nicolaidis and Damien Chardonnereau, iRoC Technologies iRoC Technologies has optimized, designed, and manufactured different test chips and processor cores to characterize the tradeoffs between various soft-error protection design schemes. The company designed 32-bit and 8-bit RISC cores implementing memory-protection and logic-time redundancy techniques. These two silicon test cases validated that logic is sensitive to soft errors and that the design process can detect, isolate, and eliminate soft errors.

SPARC efforts iRoC Technologies has optimized RoC-S81, an example of soft-error detection based on time redundancy, by inserting fault-tolerant mechanisms into the European Space Agency’s B CIN

LEON SPARC processor design.1 In addition to code-correction techniques implemented in its memory blocks, the processor includes a time-redundancy detection technique for logic blocks (no correction). Using radiation testing to compare the RoC-S81 with the original LEON design showed the RoC-S81’s integrated faulttolerant mechanisms to be efficient, although its logic parts proved to be sensitive to strikes and propagated transients. The developers used a dedicated design scheme to estimate a transient on-chip pulse width versus the particle’s energy, validating the ability to, detect within logic blocks, transient pulse width. Figure A shows this process in action, as an ion striking a transistor causes a transient fault to become a soft error.

Transient fault

U5

Soft error COUT U2

U7

A

U4 B

U6

CLK U1 Registers

Figure A. Soft-error chain. An ion striking a transistor causes a transient fault to become a soft error.

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Given that transient pulse propagation depends on the technology node and pulse width, understanding what energies atmospheric neutrons can generate when colliding with a silicon atom becomes essential. Neutrons striking silicon can generate any of more than 100 different nuclear reactions. Complete knowledge of the various combinations is necessary to identify the pertinent pulse characteristics and allow accurate fault injection, making an SER logic contribution possible. Even if protecting the chip’s memories brings a significant improvement in fault tolerance, time-out or application errors could still occur in the nonprotected logic blocks, whose contribution to the overall SoC soft-error rate ties directly to the particle’s energy. An average of 10 calculation errors per test cycle have been observed in both chips without logic block correction, only detection.

CoolRISC Based on the CoolRISC core from CSEM (the Swiss Center for Electronics and Microtechnology; www.csem.ch), iRoC Technologies developed and manufactured, for the French Space Agency (CNES), the RoC-CR11 in 180-nm silicon, implementing soft-error detection and correction on both the logic block and memory blocks. The company also manufactured a nonprotected version of CoolRISC. Both chips integrate an 8-bit logic core block, a memory controller for external and internal memory, embedded program and data memory blocks, and some external interfaces. After manufacturing, these two chips were radiation tested to assess the nonprotected CoolRISC’s sensitivity and the efficiency of the protection implemented in the RoC-CR11.

During the radiation testing, both the nonprotected CoolRISC and the protected RoC-CR11 underwent beam radiation at the same time. For a given application test and a fluency of 1.1e7, the CoolRISC’s chip output showed 60 errors. For the same application test and a fluency of 1.5e6—10 times more fluency—the RoC-CR11’s chip output showed no errors. The RoC-CR11 also implemented error detection and uncovered 148 errors in its memories and 9 errors in the logic—all of which were corrected. Developers created different applications to run on the two processors to test both the memory and logic blocks. All tests showed the same results: The nonprotected CoolRISC showed a significant number of errors, whereas the RoC-CR11 showed no die output errors. The time-redundancy implementation resulted in a 90 percent area overhead for achieving both error detection and correction in the logic elements. This compared to a projected 200 percent overhead area penalty using a more traditional time-redundancy approach. Using optimized ECC protection for memories and time redundancy for logic blocks showed no visible performance penalty. Designers must consider this significant overhead for logic protection within the overall logic-to-memory ratio in modern chips, where logic might represent only 20 percent of the die and the final application—networking, telecom, or consumer application—doesn’t need 100 percent protection. Simulating soft errors and pinpointing design hotspots will optimize soft-error protection to meet end-user reliability requirements.

Moving forward Memory blocks protection and test

Soft errors now form part of the design challenge because, like any other design constraint, there is a tradeoff between this variable and application requirements. At 90 nm and beyond, all parts of a SoC are soft-error sensitive. Reaching the 100 FIT per device target will require an in-depth understanding of the soft-error chain.

The CoolRISC and the RoC-CR11 contain 200 Kbits of embedded SRAM. The protection techniques implemented on the RoC-CR11, based on iRoC’s specific methodology for error-corrected code, share the correction code among the different 8-bit memory words to save area. The RoC-CR11 also implemented an error-detection signal to monitor the error-correction mechanisms. Protecting 100 percent of the memory required a total area overhead of 29 percent; an ECC solution would have required an overhead of 50 percent. Both chips underwent static and dynamic tests to measure the efficiency of iRoC’s soft-error protection techniques. Among the different tests performed, the RoC-CR11 detected and corrected all 80 single-bit errors in its memories, while the unprotected CoolRISC incurred 90 single-bit errors.

As with all other design variables, optimization is essential. A 100 percent soft-error protection rate is not truly needed and is too expensive for most ground-level applications. Making the most efficient tradeoff choices early in the design phase requires a predictive methodology. An SER prototyping and optimization tool well integrated in the current design flow will help designers and business unit managers make strategic decisions such as library and memory choices or even process or foundry choices.

Logic blocks protection and test

Reference

The CoolRISC and RoC-CR11’s logic blocks are latch-based designs. This implies that all the registers are implemented as latches, not flip-flops. This means that the design works by using two nonoverlapping gated clocks, which provides a power-efficient implementation. Developers designed the RoC-CR11’s soft-error detection based on iRoC’s patented time redundancy schemes. Heavy ion radiation testing (more stressful than neutron beams) demonstrated that the implemented protection technique provided 100 percent protection.

1. D. Chardonnereau et al., “32-Bit RISC Processor Implementing Transient Fault-Tolerant Mechanisms and its Radiation Test Campaign Results,’’ Single-Event Effects Symp., NASA, Apr. 2002.

Michael Nicolaidis is a cofounder of iRoC Technologies and the company’s chief technology officer. Damien Chardonnereau is a project leader and product manager for iRoC Technologies.

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Table 2. Comparison of various soft-error protection techniques. Time redundancy

Circuit-level hardening

Hardware redundancy

Technique description

Special circuit-level design techniques to decrease implemented circuits’ inherent vulnerability to soft errors.12

Undetected errors Errors logged Technology dependence Extra effort for recovery Integration with design flow Area overhead Performance overhead

Yes

Classical techniques such as triple modular redundancy (TMR) and concurrent error detection, such as duplication, parity prediction, low-cost techniques for matrix operations, and lossless data compression13 Minimal

No Yes No

Softwareimplemented hardware fault tolerance

Multithreading techniques

Multistrobe

Program instructions executed twice and results compared to detect errors; program control-flow errors detected using special control-flow checking techniques14,15

Same instruction sequence executed using two threads, then results compared to detect any errors16,17

Errors detected and corrected by strobing outputs of the same combinational logic block multiple times by delayed clocks18

Minimal

Minimal

Yes

Yes Very little

Yes Very little

Yes Very little

Yes Yes

Yes Minimal

Yes, unless TMR used Complex, recovery required Yes Minimal

Yes, unless TMR used Complex, recovery required None Yes, 40 to 200 percent

Yes, unless TMR used Complex, recovery required Some Yes, about 20 to 40 percent

Power overhead Selective insertion Areas protected

Yes Possible

Yes Possible

Yes Difficult

Yes Difficult

Yes, unless TMR used Complex, recovery required Yes Minimal for error detection, can be significant for error correction Yes Possible

Mainly sequential elements

Architectural impact Applicability

Minimal

Sequential elements and combinational logic Yes

Sequential elements and combinational logic None

Sequential elements and combinational logic Yes

Sequential elements and combinational logic Yes

Unlimited

Unlimited

Mainly microprocessors

Mainly microprocessors

Unlimited

Parameters

Simple

the SER contribution of combinational logic for state-of-the-art processes is still considerably smaller compared to contributions of unprotected SRAMs and sequential elements. Hence, the chiplevel SER trend is dominated by the SER trends of SRAMs and sequential elements such as latches and flip-flops. Even if the SER per SRAM bit or latch remains constant over technology generations, integration of more devices in advanced technologies results in higher chip-level SER. In contrast, customer expectations for SERs will either remain constant or become more stringent in advanced technologies.

SOFT-ERROR PROTECTION TECHNIQUES Designers can use several strategies to provide soft-error protection. These include circuit-level 48

hardening, classical hardware redundancy, and time redundancy techniques. The “Soft-Error Protection: Test Results” sidebar discusses radiation testing of some soft-error protection techniques. Table 2 shows a comparative analysis of these techniques with respect to several system-level metrics, exploring some variables and factors that determine their applicability to actual designs.

REUSE PARADIGM FOR BUILT-IN SOFT-ERROR RESILIENCE A new paradigm that leverages the reuse of onchip resources for multiple functions at various stages of manufacturing and field use can overcome the drawbacks of existing soft-error protection techniques. For example, designers can reuse

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SCB Scan portion SI

1D

SCA

on-chip scan design-for-testability resources for soft-error protection during normal operation. Scan design for testability has become a de facto test standard because it provides an automated solution to high-quality production testing. In addition, scan is extremely valuable for postsilicon debug activities19,20 because it provides access to an integrated circuit’s internal nodes. Figure 3 shows a microprocessor scan flip-flop design20 that comprises two distinct circuits: a system flip-flop and a scan portion. All scan flip-flops in a design are connected together as one or more shift registers. The SI input of a scan flip-flop is connected to the SO output of the preceding scan flipflop in the shift register. The SO output of a scan flip-flop is connected to the SI input of the following scan flip-flop in the shift register. The structure of the scan portion of Figure 3 is similar to the system flip-flop, with the addition of interface circuits to move data between the system flip-flop and the scan portion, as well as shifting the test pattern and test response, as required by the specific scan architecture. This design has two operation modes: normal-system operation and test. In the test mode, clocks SCA and SCB are applied alternately to shift a test pattern into latches LA and LB. Next, the UPDATE clock is applied to move the contents of LB to PH1. Thus a test pattern is written into the system flip-flop. Next, functional clock CLK is applied, which captures the system response to the test pattern. Finally, the CAPTURE signal is applied to move the contents of PH1 to LA. The system response is then

1D

C1

Latch 2D LA CAPTURE

C1

C2

1D UPDATE

C1

D

1D C1

CLK

SI SCA

Latch PH2

C2 System flip-flop

shifted out by alternately applying clocks SCA and SCB. During normal system operation, the scan portion is shut off by asserting logic-0 values to the scan signals (SCA, SCB, UPDATE, and CAPTURE). There are three basic reasons for using the scan style of Figure 3: structural testing using automated test pattern generation tools, functional testing using signature analysis, and efficient postsilicon debug.18 The opportunity for scan reuse for soft-error protection arises from the redundant scan resources— latches LA and LB in Figure 3—that are unused during normal operation, but add to the occupied area of the chip and the leakage power during normal operation. Figure 4 shows how reusing the scan flip-flop design can reduce the impact of soft errors that affect latches. The flip-flop design’s test mode operation is identical to the design in Figure 3. In normal system operation mode, the scan clocks SCA, SCB, UPDATE, and TEST are forced low, while the

CAPTURE

Scan portion 1D C1

Latch 2D LA

1D C1

Q

Latch 2D PH1

C-element truth table SCB

SO

Latch LB

O1 0 1 0 1

O2 0 1 1 0

Q 1 0 Previous value retained Previous value retained SO

Latch 02 LB C-element

Keeper

C2

Figure 3. Microprocessor scan cell design. The design has two operation modes: normal-system operation and test.

Figure 4. Scan reuse. Soft-errorblocking flip-flop design with a Celement. Reusing the scan flip-flop reduces the impact of soft errors that affect the latches by more than 20 times.

1D UPDATE D

CLK TEST

C1 1D C1

Latch PH2

01

Q

Latch 2D PH1 C2 System flip-flop

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Figure 5. Errortrapping scan cell design. Latches LA and LB store redundant copies of PH2’s and PH1’s contents, respectively, during normal operation. A soft error in any latch causes the error signal (E) to be 1. Once E is 1, the logic values stored in LA and LB become complements of the contents of PH2 and PH1, respectively, and E continues to be 1, trapping the error until another soft error affects one of the latches, which rarely occurs.

50

SCB

Scan portion

SI SCA

XOR2

1D C1 D1

Latch 2D LA

CAPTURE

1D C1

SO (Q2)

Latch LB

C2 XOR1 E 1D UPDATE D

CLK

Q

C1 1D C1

Latch PH2

Latch 2D PH1 C2 System flip-flop

CAPTURE signal is forced high. This converts the scan portion into a master-slave flip-flop that operates as a shadow of the system flip-flop. During normal operation, when the clock signal CLK is 0, the C-element output drives flip-flop output Q, and the chip transfers the logic value at input D into latches LA and PH2. During this time, latches PH1 and LB are susceptible to soft errors because their clock inputs are 0 and they are holding logic values. If a soft error occurs in PH1 or LB, the logic value on O1 will not agree with O2. As a result, the error will not propagate to output Q, and the keeper will hold the correct logic value at Q. A soft error in PH2 or LA when CLK = 1 produces similar results. Depending on the system’s speed and the leakage current, the keeper in Figure 4 might not be necessary. Extensive SER simulations on an advanced process technology using an internal tool5 show that this design can reduce the SER by more than 20 times compared to the error rate for an unprotected flip-flop. Any soft error affecting a single latch inside a flip-flop is guaranteed to be detected by a selfchecking scan flip-flop that is obtained by removing the C-element and the associated keeper structure from the design in Figure 4. Various selfchecking scan cells choices are possible. During normal operation, at least one copy of correct data exists, under the assumption of a single error in a latch. To perform self-checking, the approach implements error-detection circuits such as equality checkers that compare the Q and Q2 outputs of all such flip-flops in a design and indicate an error each time a mismatch occurs. A major drawback of such a self-checking approach is the significant amount of area occupied by the logic network that accumulates the error signals generated by individual flip-flops and

produces one or more global error signals. The error-trapping scan cell shown in Figure 5 eliminates this problem. Latches LA and LB store redundant copies of the PH2 and PH1 content, respectively, during normal operation. A soft error in any latch causes the error signal (E) to be 1. This signal drives the top input of the exclusive-or gate XOR2 so that when E equals 1, the output of XOR2 (D1) becomes the complement of D. Once the error signal E is 1, the logic values stored in LA and LB become complements of the contents of PH2 and PH1, respectively, and E continues to be 1. Thus, the error is trapped until another soft error affects one of the latches of this flip-flop, which is a rare event. After a prespecified number of clock cycles, at a recovery point the system shifts out this trapped error signal using the existing scan path, which eliminates the need for global routing of error signals at the cost of error-detection latency. Re-execution then achieves error correction.13 Table 3 shows the results generated by performing circuit simulations on a typical process corner for an advanced technology to compare the softerror-resilient scan flip-flops and a conventional scanned flip-flop. To evaluate the system-level impact of soft-errorresilient scan cell designs, we estimated the chiplevel area and power overheads of new soft-error resilient scan flip-flop designs in Table 4, assuming that 25 percent of the flip-flops are protected from soft errors.8 The results showed that the overall power and area overheads for all proposed designs are less than 5 percent and 0.3 percent, respectively. Such relatively low overheads, combined with the expected high gain in soft-error resilience, justify the use of proposed designs in various applications. Several optimizations are possible to further reduce the system-level power overhead to 3 percent or less.

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Table 3. Relative cell-level timing, power, area, and soft-error rate comparisons. Approach

Scannable

D-to-Q

C-to-Q

Power

Area

Global interconnect

Yes

1.00

1.00

1.00

1.00

None

1.00

Yes

1.00

1.08

2.13

1.08

None

< 0.05

Yes

0.99

0.99

2.02

0.95

Yes

0.97

0.99

2.26

1.24

Several for error accumulation Reused from existing scan path

Master/slave flip-flop Error-blocking design Self-checking design Error-trapping design

Undetected soft-error rate

0 0

Table 4. Chip-level power area and performance overhead, by percent. Approach Error-blocking design Self-checking design Error-trapping design

Power overhead 4.5 4.0 5.0

The reuse paradigm for built-in soft-error resilience offers the following unique advantages over existing soft-error protection techniques: • minimal area overhead because resources already available for test and debug can be reused for soft-error resilience; • minimal routing overhead; • no major architectural changes required; • applicability to any design—microprocessors, network processors, and ASICs; and • a broad spectrum of design choices with several area, power, performance, and soft-error rate tradeoffs. For example, the design shown in Figure 4 can be redesigned to achieve a 50 percent rather than a 20 times reduction in the SER, with a 30 percent reduction in the celllevel power overhead.

oft-error rates are getting worse for systems manufactured in advanced technologies with very high levels of integration. Stringent data integrity and the availability requirements of enterprise and networking applications demand special attention to soft errors not only in SRAMs but also in sequential elements and combinational logic from the very early phases of product development forward. Applying the reuse paradigm for built-in soft-error protection significantly reduces the system-level soft-error rate and introduces minimal overhead. Automated techniques for architectural-vulnerability-factor estimation are required to further reduce the system-level power, performance, and area overheads of these techniques. ■

S

Area overhead 0.10 -0.06 0.30

Performance overhead 0 0 0

Acknowledgments For their help with this article, we thank R. Fuller, J. Maiz, and T.M. Mak of Intel, and E.J. McCluskey of Stanford University.

References 1. D. Lyons, “Sun Screen,” Forbes Magazine, 2000; www.forbes.com/forbes/2000/1113/6613068a.html. 2. R. Wilson and D. Lammers, “Soft Errors Become Hard Truth for Logic,” EE Times, 3 May 2004; www. eetimes.com/semi/news/showArticle.jhtml?articleID= 19400052. 3. D.C. Bossen, “CMOS Soft Errors and Server Design,” Workshop on Radiation Induced Soft Errors, Proc. IEEE Int’l Reliability Physics Symp., IEEE Press, 2002. 4. “Increasing Network Availability”; www.cisco.com. 5. H.T. Nguyen and Y. Yagil, “A Systematic Approach to SER Estimation and Solutions,” Proc. IEEE Int’l Reliability Physics Symp., IEEE Press, 2003, pp. 6070. 6. N. Seifert and N. Tam, “Timing Vulnerability Factors of Sequentials,” IEEE Trans. Device and Materials Reliability, Sept. 2004, pp. 516-522. 7. K.K. Goswami, R. Iyer, and L.Y. Young, “DEPEND: A Simulation-Based Environment for System-Level Dependability Analysis,” IEEE Trans. Computers, Jan. 1997, pp. 60-74. 8. N.J. Wang et al., “Characterizing the Effects of Transient Faults on a High-Performance Processor Pipeline,” Proc. Int’l Conf. Dependable Systems and Networks, IEEE Press, 2004, pp. 61-70. 9. S.S. Mukherjee et al., “A Systematic Methodology to Compute the Architectural Vulnerability Factors for a High-Performance Microprocessor,” Proc. Int’l February 2005

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Symp. Microarchitecture, IEEE CS Press, 2003, pp. 29-40. 10. P. Hazucha et al., “Neutron Soft Error Rate Measurements in a 90-nm CMOS Process and Scaling Trends in SRAM from 0.25-µm to 90-nm Generation,” Proc. Int’l Electron Devices Meeting, 2003, pp. 21.5.1-21.5.4. 11. R. Baumann, “The Impact of Technology Scaling on Soft-Error Rate Performance and Limits to the Efficacy of Error Correction,” Proc. IEEE Int’l Electron Devices Meeting (IEDM02), IEEE Press, 2002, pp. 329-332. 12. P. Hazucha et al., “Measurements and Analysis of SER-Tolerant Latch in a 90-nm Dual Vt CMOS Process,” IEEE J. Solid State Circuits, Sept. 2004, pp. 1536-1543. 13. D.P. Siewiorek and R.S. Swarz, Reliable Computer Systems Design and Evaluation, 3rd ed., A.K. Peters, 1998. 14. N. Oh, P.P. Shirvani, and E.J. McCluskey, “Error Detection by Duplicated Instructions in Super-Scalar Processors,” IEEE Trans. Reliability, Mar. 2002, pp. 63-75. 15. N. Oh, S. Mitra, and E.J. McCluskey, “ED4I: Error Detection by Diverse Data and Duplicated Instructions,” IEEE Trans. Computers, Feb. 2002, pp. 180199. 16. N.R. Saxena et al., “Dependable Computing and OnLine Testing in Adaptive and Reconfigurable Systems,” IEEE Design and Test of Computers, Jan.Mar. 2000, pp. 29-41. 17. S.S. Mukherjee, M. Kontz, and S. Reinhardt, “Detailed Design and Evaluation of Redundant Multithreading Alternatives,” Proc. Int’l Symp. Computer Architecture, IEEE CS Press, 2002, pp. 99-110.

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18. M. Nicolaidis, “Time Redundancy-Based Soft-Error Tolerance to Rescue Nanometer Technologies,” Proc. IEEE VLSI Test Symp., IEEE Press, 1999, pp. 86-94. 19. A. Carbine and D. Feltham, “Pentium Pro Processor Design for Test and Debug,” Proc. Int’l Test Conf., IEEE Press, 1997, pp. 294-303. 20. R. Kuppuswamy et al., “Full Hold-Scan Systems in Microprocessors: Cost/Benefit Analysis”; http:// developer.intel.com/technology/itj/2004/volume08 issue01/.

Subhasish Mitra, a senior staff engineer at Intel, is also a consulting assistant professor in the Electrical Engineering Department at Stanford University and the associate director of the Stanford Center for Reliable Computing. His research interests include robust system design, VLSI design and test, fault-tolerant computing, and computer architecture. Mitra received a PhD in electrical engineering from Stanford University. Contact him at [email protected]. Norbert Seifert is a design and reliability engineer at Intel. His research interests include the interdependence of design and system reliability. Seifert received a PhD in physics from the Technical University of Vienna, Austria. Contact him at Norbert. [email protected]. Ming Zhang is an intern at Intel and a PhD candidate in the Department of Electrical and Computer Engineering at the University of Illinois at UrbanaChampaign. His research interests include design and modeling of reliable circuits and systems. Zhang received an MS in electrical engineering from the University of Illinois at Urbana-Champaign. Contact him at [email protected]. uiuc.edu. Quan Shi is a senior design engineer at Intel. His research interests include circuit-hardening techniques, circuit modeling and validation, and asynchronous circuits. Shi received a PhD in electrical engineering from the University of New Mexico. Contact him at [email protected]. Kee Sup Kim is the director of DFX—Design for Test, Reliability, Manufacture, and Debug—for communications products at Intel. His research interests include the four DFX areas, especially structural test, speed-defect coverage, BIST, and quality risk assessment. Kim received a PhD in electrical engineering from the University of WisconsinMadison. Contact him at [email protected].

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COVER FEATURE

Transistor-Level Optimization of Digital Designs with Flex Cells The flex-cell approach, either alone or in combination with standard cells, provides an optimally tuned set of building blocks for integrated circuit design when optimality is measured using accepted and quantifiably definable metrics such as clock speed, die size, and power consumption.

Rob Roy Debashis Bhattacharya Vamsi Boppana Zenasis Technologies

0018-9162/05/$20.00 © 2005 IEEE

A

s early as the mid-1980s, researchers studying the performance gap between handcrafted custom and standard-cellbased synthesized designs1 found that a fixed and limited set of library elements constitute a major bottleneck in achieving target quality. More recently, researchers have estimated that as much as 25 percent of the quality gap between automatically created and handcrafted designs can be attributed to the fixed set of cells in a predefined library. These libraries enable quick generation of a broad range of possible designs, but are not optimized for the timing context found in any particular one. A standard-cell-based automated design flow for digital circuits offers a mixed blessing. Historically, the use of precharacterized and silicon-verified standard cells has been driven by the designers’ need to create and verify large digital circuits without having to verify the circuit’s behavior at the transistor level. Transistor-level design and verification of a multimillion-gate digital circuit is simply too resource-intensive to be commercially viable for most designs. Standard cells thus provided relatively fine-grained control over the digital circuit’s structure, yet allowed a team of fewer than 10 engineers to design complex digital integrated circuits using automated synthesis tools.

On the other hand, the quality of automated standard-cell-based designs has always ranged from poor to barely acceptable at best. Researchers have estimated that designs created using these automated-design flows run slower by at least a factor of 6 and consume a larger design area by at least a factor of 10, compared to similar designs created or optimized manually. Up to one-quarter of this quality deficiency can be traced to using a fixed, predefined library of standard cells. Over the years, it has become commonplace to perform various forms of manual intervention on designs generated using automated flows. Among these, using special macrocells and tactical cells has become virtually routine for all high-performance designs created using automatic design tools, especially for designs that run into timing-closure problems. These problems occur because of inaccurate timing estimations during automated design creation. They usually can be linked to incorrect estimation of the interconnect load and delay characteristics. According to market research surveys conducted by Collett International, more than 60 percent of all ASIC designs have timing-closure problems.2 The quest to overcome the limitations of standard-cell-based design methods leads naturally to the creation of new design- and context-specific

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Database Netlists: 1. Standard cells only 2. Standard + flex cells

Libraries 1. Standard cell 2. Flex cell (including layout) Cluster information

New flex cell Flex cell generation (mapping to transistors)

Uniquification (minimal set of flex cells)

Decision diagrams External constraints

Other data: timing, area, extracted parasitics

Flex cell information

Analysis results

Design information

Objective analysis (for example, timing)

Creation of necessary views and models, including characterization

Create flex cell New cluster

Flex cell found/not found

Global optimization (for example, buffering and sizing)

Clustering-based local optimization (driven by static timing analysis) Constraints

Results

Master optimization control (driven by static timing analysis) Reports

Constraints

User interface

Library

1. User commands 2. Parsers 3. External interfaces: flex cell layout, formal verification, output netlist generation, flex cell library generation, report generation

Netlist Physical data

Figure 1. IC design optimization process using flex cells. These design- and context-specific cells enhance system performance by increasing clock speed.

New netlist Driver scripts

cells—designated flex cells—during the process of optimizing a given digital design. The design community openly acknowledges that virtually every high-performance design project that relies on automated design flows also uses designspecific tactical cells that developers identify and create manually. They then use these cells in the design via a combination of a register-transfer-level coding style and synthesis directives. Without the use of these cells, the gap in quality between automated and handcrafted designs would be even wider. From a superficial viewpoint, flex-cell-based design optimization automates the creation of tactical cells, thereby helping to bridge the quality gap. However, a deeper examination of the flex-cellbased optimization process makes it amply clear that the full impact of such optimization goes far beyond providing a better framework for creating tactical cells.

FLEX-CELL-BASED OPTIMIZATION The IC design optimization process shown in Figure 1 is geared toward enhancing the design’s performance—specifically, increasing clock speed. The time-tested manual process of locally optimizing a digital design driven by global analysis inspired this design optimization approach. In this design, the global analysis consists of accurate static-timing analysis,3 while local optimization con54

New library

sists of an overall control mechanism employing two key steps: clustering and mapping.4,5 To optimize performance, the clustering process identifies the best candidate regions in the design for local optimization, a search driven by the statictiming analysis’s results. The clustering process yields a set of clusters—groups of one or more standard cells—that must be replaced by new flex cells created for their respective timing contexts. The mapping process takes as inputs the clusters and their timing contexts, then determines a reasonably small set of best-candidate flex cells that should be used to replace the clusters. The optimization control process searches through this set of cells to determine whether replacing one or more clusters with flex cells will improve the given design’s overall timing. The close coupling between the clustering and mapping processes is key to this technique’s success. Specifically, the mapping process6 is tailored to choose from a variety of techniques that can be used to create new flex cells, based on the inputs it receives from the clustering process. Such mapping techniques can include time-tested methods such as gate sizing and continuous transistor sizing, as well as techniques typically found in custom design flows, such as creating new, appropriately sized transistor-level implementations of the function for a given standard-cell cluster.

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Cluster of standard cells, various context-specific constraints for this cluster, other real-life constraints such as process

Map to transistor-level candidate netlists for flex cell

Transistor sizing

(No)

Fast (prelayout) characterization

Create transistor-level netlist with systematic redundancy, if permitted

Meets requirements?

Layout synthesis

Postlayout characterization Detailed characterization Meets requirements?

(No)

Set of candidate flex cells

Various interfaces to evaluate and fit flex cell into standard-cell-based design flow

PRACTICAL MAPPING CHOICES The mapping process can be quite involved. At a minimum, it includes the following: • ensuring functional correctness of the resultant transistor-level design; • meeting design targets, for example, performance (possibly measured using propagation delay) of the generated flex cells, given the timing contexts for their intended use; • meeting other implementation constraints, such as maximum length of N- or P-transistor chains in the flex cell, the required output drive strength for the design-specific cell, desired input capacitive load of the design-specific cell, and so on; • minimizing the number of transistors in the design-specific flex cells, subject to the IC design’s characteristics; and • sizing the transistors in the design-specific cells, as necessary. Figure 2 shows a more detailed view of the mapping process. The inputs to the process can include the following: • a set of structural netlists composed of standard cells, otherwise known as clusters;

• a set of performance constraints for each individual cluster; and • important process-dependent parameters like transistor SPICE models (developed originally at UC Berkeley, SPICE is the most widely used simulation tool for transistor-level designs). A clustering process, which precedes the mapping process shown in Figure 1, identifies the set of clusters and the performance constraints for them. The clustering step essentially partitions a conventional logic synthesis tool’s output, using either heuristics to guide the partitioning or a systematic search procedure such as a branch-and-bound search. Key steps of the mapping process include the following: • creation of a transistor-level netlist; • fast characterization that incorporates the flex cells’ implementation context; • transistor sizing; • accurate but slower characterization of the final transistor-level netlist; • optional layout synthesis with transistor sizing, via a layout synthesis tool; • parasitic extraction and accurate postlayout characterization if layout synthesis is performed; and

Figure 2. Flex-cell mapping process. Tailored to choose from a variety of techniques that can be used to create new flex cells, this process ensures functional correctness, meets design targets and other implementation constraints, and minimizes the number of transistors in design-specific cells.

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Figure 3. Flex-cell generation. Starting with (a) the original cluster of standard cells, the mapping process (b) creates a flex cell that replaces the cluster and (c) improves performance.

c

d

a

ba

a

a

c

b

d

d

a

d c

b

(a)

(b) Transition on input # a b c d

Original Rise (ns) 0.29 0.18 0.18 0.18

Fall (ns) 0.34 0.30 0.31 0.27

Optimized Rise (ns) 0.13 0.17 0.16 0.15

Fall (ns) 0.11 0.13 0.15 0.14

(c)

• generation of views to fit the flex cells into a standard-cell-based design flow. This process contrasts sharply with conventionally automated, transistor-level design optimization techniques that derive their benefits primarily from transistor sizing.7 Creation of a transistor-level netlist during mapping includes the four key substeps shown in Figure 2: transistor netlist generation, netlist evaluation, topology alteration, and sizing. Given the original cluster, the mapping can use a variety of algorithms and heuristics to generate a transistor netlist. For example, several techniques for deriving transistor netlists use binary decision diagrams as starting points to represent the cluster’s function. Based on acyclic directed graphs, BDDs can be used to represent common functions in digital circuits, including transistor netlist structures.8,9 Despite starting with multiple algorithms, the transistor-netlist-generation process might not yield topologies that meet the constraints its use context imposes on the cluster. In such cases, the process must alter the topology to explore multiple alternative implementations, given the cluster’s functionality. For example, the process can include using a variable reordering in the cluster’s decision diagram representations. The topology alteration process also can use multiple decomposition methods, such as the Boole-Shannon, Kronecker, RothKarp, Positive Davio, Negative Davio, and Ashenhurst techniques.1 Researchers can use various metrics, derived from the constraints mentioned earlier, to evaluate the results from the topology alteration process and obtain a ranked list of flex cells. In this list, a higher rank indicates greater suitability for use in the given context. 56

For timing optimization purposes, an appropriate mix of SPICE-like transistor-level timing analysis as well as faster and more approximate switch-level timing analysis techniques—for example static-timing analysis at the switch and transistor level—is key to ranking the candidate transistor netlist topologies properly. Figure 3 shows some results of and uses for the flex-cell generation process. This diagram shows the flex cell that results when a portion of an IC design is mapped to transistors, with the primary goal being performance optimization. Figure 3a shows the cluster in question. It has only one critical input, input a. In this context, a critical input is the delay from this input to the cell’s output, which limits the cell’s overall performance. Figure 3b shows a candidate flex cell generated by the mapping process. Figure 3c shows the performance improvement that would result from replacing the cluster with the flex cell. Although this description implicitly focuses on the static CMOS family of logic circuits, if the target IC design implementation uses another family of MOS circuit design—including various forms of dynamic CMOS, a combination of static and dynamic CMOS, and so on—this mapping process also could be applied broadly to the creation of NMOS or PMOS networks for such logic families.

MINIMIZING THE NUMBER OF NEW FLEX CELLS CREATED As Figure 1 shows, the flex-cell-based optimization process can invoke a process to minimize the number of functionally unique flex cells created when optimizing a given design. In the context of flex-cell synthesis, this process focuses on identifying the minimum number of unique flex cells required for optimization and thus differs from the

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Context is not known Consider all single-input transitions a

0 1 0 0 1 0 0 0 1 0 0 1 0 1 1 ...

uniquify command found in synthesis tools. Further, given that developers fully expect a predefined standard-cell library to be available as an optimization process input, they also can use the process to identify near or exact matches, depending on the IC or flex-cell design’s tolerance. As a matter of policy, if transistor-level implementations of the standard cells are available as optimization process inputs, creating flex cells that have equivalent or near-equivalent matches in the available standard-cell library should be avoided, within limits. Clearly, practical considerations must drive the choice to create a new flex cell or not. However, exceptions to this policy might be necessary when creating, for example, new flex cells that represent library cell-sizing variations. In the context of flex-cell-based synthesis, especially synthesis aimed at enhancing the target design’s performance, this process must take into account both functionality and the timing contexts in which each unique cell will be used. Thus, in addition to functionality, the matching target is annotated with timing constraints related to its intended use in a design. Although here we focus on timing, in general, constraints specified as part of the target can be related to various other metrics such as power, area, noise margins, slew, input and output capacitances, drive strength, footprint size, and pin placement.

CELL LAYOUT SYNTHESIS During the mapping process shown in Figure 1, automated-cell-layout synthesis10,11 plays a key role in closing the loop with respect to creating actual layouts of the flex cells designed as transistor-level netlists. Layout synthesis takes as input the flex cells’ netlists, various fabrication process technology parameters—including layout design rules, desired standard-cell architecture parameters such as cell height, number of tracks, and implant specifications—and creates the detailed transistor layout. This layout consists of polygons that eventually will be fabricated on silicon substrate. Layout synthesis commonly includes further tuning the transistors’ sizes in the flex cells with the goal of ensuring that the cells’ timing characteristics, postlayout, closely match the desired timing characteristic passed to layout synthesis as input. During the layout synthesis step, designers strive to achieve compatibility with standard cell library blocks to seamlessly mix the created flex cells with the predefined standard cells used in the rest of the

b

0 0 0 0 0 0 0 1 1 1 1 1 0 0 0 ...

Z

f

c

0 0 0 1 1 1 0 0 0 0 1 0 0 0 1 ...

(a) Context is known Consider only some input transitions

a

00111 Inputs

. . .

b

00011

Z

f

c

01001

. Outputs . .

(b)

design. The compatibility of the flex cells and standard cells, at the layout level, ensures that the final IC design can be highly customized while remaining flexible enough to allow using standard cells where possible or needed.

PERFORMANCE ENHANCEMENT As Figure 2 shows, our process repeatedly uses a fast characterization step during mapping to obtain estimates of the flex cells’ timing characteristics. This is possible because the design constraints are known and have been used as the basis for generating the flex cells. Using appropriately chosen characterization mechanisms throughout the mapping and optimization process is key to the success of such flex-cell-based design optimization techniques. Broadly speaking, characterization mechanisms used during optimization can be divided into two phases: prelayout and postlayout. The prelayout phase includes flex cell characterization at creation, taking the context of use into account. Using context-dependent information at this stage allows more accurate characterization and reduces the resources needed for this function. Figure 4 shows this process: Cell Z has three inputs, a, b, and c. Conventional methodology can instantiate Cell Z in any portion of the design. Hence, a characterization method that lacks knowledge of the cell’s use context must consider the possibility that signal transition can propagate from any input to the output, for any possible valid input combination on the other inputs. In contrast, in alternative design flows that generate flex cells on the fly, the places the cell instan-

Figure 4. Contextdependent flex-cell characterization. (a) A conventional methodology can instantiate Cell Z in any portion of the design. (b) In contrast, the alternative design flows that generate flex cells on the fly allow only a subset of the possible input transitions to be used for characterization, which speeds processing.

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Table 1. Propagation delay comparison of gate-level static-timing and transistor-level-timing analyses. Drive strength at each of four stages 1 2 3 0 1 2 4 0

0 1 2 4 1

0 1 2 4 2

Static timing, in nanoseconds 4 0 1 2 4 4

0.40 0.22 0.15 0.61 0.41

Transistor-level timing (SPICE), in nanoseconds 0.186 0.166 0.157 0.581 0.332

tiates in the design define the cell environment. Hence, certain input value combinations may not be applicable to Cell Z. In Figure 4b, for example, the design flow only needs to consider a subset of the possible input transitions because of Cell Z’s known design context. The benefits of prelayout characterization become more pronounced when applied to a group of standard or flex cells. Consider, for example, a simple four-stage chain of NAND gates. Table 1 compares the worst propagation delays through this gate chain, as determined by both gate-level static-timing analysis and transistor-level timing analysis for five circuits. Each row in Table 1 represents one unique circuit configuration. The first four columns in Table 1 represent the drive strength of the gates at each stage, where zero represents the smallest drive strength and four represents the largest. The static timing and transistorlevel timing columns represent the worst propagation delay through the same design, based on the analysis of representative state-of-the-art processes and delay models. The same load capacitance and input slew values were used for each run. Clearly, transistor-level timing analysis is more accurate than gate-level timing analysis. The differences in timing analyses can vary dramatically in certain kinds of configurations, as seen in the first circuit configuration in Table 1, where each NAND gate has 0 drive strength. These differences vary based on factors such as the delay models being used, circuit topology, the model extraction technology, the choice of transistor simulation techniques, the targeted fabrication process, circuit design style, and the drive strengths of the circuits under consideration. In general, gatelevel static-timing analysis is inherently conservative to account for potential inaccuracies in deriving the gate-level abstraction from the transistor-level circuit. The well-known conservative nature of gate-level static-timing analysis improves accuracy because it considers clusters of standard cells and analyzes and optimizes these clusters at the transistor level. Physically placing members of such clusters in close proximity to each other to make a new cell with a 58

predefined shape, then characterizing the entire group as one entity at the transistor level provides a more accurate estimate of timing than can be achieved with gate-level static-timing analysis.

PHYSICAL DESIGN AND OPTIMIZATION As the minimum feature size of fabrication processes has decreased to 0.18 µm and smaller, it has become virtually impossible to create designs, especially high-performance designs, without incorporating detailed physical design information into the synthesis and optimization process. The dominant factor guiding this development is the greater role that interconnect delays play in determining a design’s overall critical-path delay. Static-timing analysis in flex-cell-based design must take into account actual wire delays, loads, and slew degradation differences between different parts of the same interconnect net—or use good estimates thereof derived from physical design knowledge. The local optimization steps, including clustering and mapping, must also consider the impact of these factors with regard to nets of interest. Various intermediate steps can be taken, as flexcell-based optimization transitions from traditional wire-load model-based computation to physical design-based load computation. The necessary step of understanding the standard and flex cells and estimating the wire lengths of individual nets is best done using well-known parameters such as halfperimeter, number of net terminals, and fraction of the bounding box covered by cells and occupied by blockages.12 At high utilization, or in the presence of severe congestion, more detailed routing information is essential to allow accurate estimation of the delays and loads that the flex-cell-based optimization tool must take into account at various stages. Key to incorporating this data into the optimization process is the use of fast incremental placement algorithms. These algorithms can be based on well-known techniques such as quadratic placement, force-directed placement, and simulated annealing13—or on some appropriate combination of multiple placement techniques. Important issues that require careful attention for effective use of incremental placement include the following: • execution time of the incremental placement algorithm, and • quality of result—as measured by correlation to the final placement that the place-and-route tool used for the actual layout will generate.

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a

c

d

a

ba

Figure 5. Structural comparison of unoptimized cells versus an optimized flex cell.

a

c

a

d

b

d c

d

b

Table 2. Performance comparison of an unoptimized cell and an optimized flex cell.

A B C D

Original cell, in nanoseconds Rise Fall 0.29 0.18 0.18 0.18

A practical solution may require making a variety of tradeoffs to achieve the desired speed, at the potential cost of some quality degradation. These tradeoffs might include the following: • relaxing the requirements to generate legal placements, thus allowing some design rule violations like cell overlap; • invoking incremental placement after a set of optimization steps complete as opposed to invoking incremental placement after every change made during optimization; and • using simpler algorithms like force-directed placement, as opposed to more sophisticated placement techniques.

CASE STUDIES Results from experimental studies help to demonstrate the substantial benefits that can be derived from using crafted flex cells to custombuild a design context. These studies also provide evidence that applying this methodology in current designs is feasible. The first experiment demonstrates the savings achievable by replacing a set of conventional standard cells with a customized flex-cell implementation. Figure 5 and Table 2 show these results, which document the structural and timing advantages of flex cells, respectively. Figure 5 shows that the conventional standardcell implementation used five cells, 22 transistors, and nine wires, while the optimized flex-cell implementation reduced to a single cell that consists of only 13 transistors and zero global wires. Table 2 shows various characteristics of the new implementation, including significant improvement in timing characteristics. In the design context for

Optimized flex cell, in nanoseconds Rise Fall

0.34 0.30 0.31 0.27

0.13 0.17 0.16 0.15

0.11 0.13 0.15 0.14

this example, the project team created the flex cell to optimize the critical path in the design between the input and output. The worst-case delay for that critical path improved from 0.31 ns in the conventional implementation to a remarkable 0.13 ns in the flex-cell implementation. Consider how the introduction of flex-cell-based optimization can alter a design’s worst critical paths. The graph in Figure 6 plots the number of paths violating a specific timing constraint against the timing constraint for two versions of another adder design. A state-of-the-art, commercial, standard-cell synthesis tool produced the first design, represented by the outer curve. The second design, represented by the inner curve, was obtained by applying flex-cell-based optimization to the original design.

Figure 6. Using flex cells to reduce the number of paths that violate timing constraints.

10,000 4,853

Original Flex cells

3,273 1,994 1,063

1,000 Number of paths

Transition on input #

463 173

100

37 10 4 1 0.90

0.95

1.00

1.05 1.10 Time (ns)

1.15

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1.20

1.25

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0.4 Before optimization (ns)

1.67

1.74

1.87

1.89

1.99

2.04

2.18

2.23

Z ADD Z After optimization 0.4 (ns)

Figure 7. Flex-cellbased optimization of critical-path timing. Optimization improved the performance of this timing-path set by 19 percent.

1.56

1.61

1.71

Figure 7 shows how applying flex-cell-based optimization can improve individual timing paths. Here, the original critical path ran at 2.23 ns, while flexcell-based optimization reduced the critical path delay to 1.83 ns, an improvement of 19 percent over the combinational path delay on this timing path set. Other data shows the feasibility of using flex cells in an automatic design optimization procedure. One potential difficulty with using flex cells is that the time-consuming process of creating their layout can interfere with the speed of front-end optimization and synthesis tools. This can be overcome using highly accurate estimators of postlayout parasitics, given a flex cell’s prelayout SPICE netlist and various details of the target cell architecture and process rules. Experiments on a large set of flex cells indicate that using such estimators, even for a characteristic as sensitive as timing data, can bring prelayout data to within from 5 to 6 percent of postlayout data, as shown in Figure 3c. Further, the prelayout data can be tuned to be slightly pessimistic, thus eliminating costly optimization and place-and-route iterations. Finally, we summarize the results of using flexcell-based optimization on some industrial designs, used in practice, that range from 7,000 placeable instances and approximately 30,000 gates to roughly 80,000 placeable instances and 320,000 gates, designated CKT1 through CKT5. Table 4 shows the results of this approach.

1.76

1.81

1.88

Clearly, use of flex-cell-based optimization methodology can achieve performance enhancements ranging from 10 to 20 percent. As tools built with flex-cell-based optimization methodology mature, we expect to achieve a performance improvement significantly greater than 20 percent over and above what traditional standard-cell-based design optimization flows can deliver.

SICs have a place in digital circuit design. In certain applications, the economics and other practical considerations make it the best method. Custom ICs achieve the best performance and will continue to do so in the foreseeable future. However, there are some techniques that can be borrowed from the custom design method—optimization at the transistor level, for example, which can be automated and thus become a viable extension of current ASIC design methodology. This is the essence of the flex-cell approach, which either alone or in combination with standard cells provides an optimally tuned set of building blocks for the target IC design when optimality is measured using accepted and quantifiably definable metrics such as clock speed, die size, and power consumption. By allowing manipulation of the transistor-level structures, flex cells open up a

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Table 4. Flex-cell-based industrial design optimizations.

Design CKT1 CKT2 CKT3 CKT4 CKT5

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Total number of instances, initially 7017 18,265 33,940 38,310 80,277

Number of unique flex cells added 96 49 165 132 80

Total number of flex-cell instances added 500 183 3,821 5,927 640

Final total number of instances 6,951 18,275 34,389 36,192 78,639

Initial clock frequency (MHz) 339 167 187 297 188

Final clock frequency (MHz) 400 193 219 345 206

Performance improvement (percent) 18 16 18 16 10

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Runtime (hours) 5 8 33 35 5

new dimension in the optimization of automatically created designs. Practical results using flex-cell-based optimization suggest that when employed properly, this methodology holds the promise of significantly benefiting the automatic optimization of digital designs. Achieving this would represent a significant step toward bridging the performance gap between custom and ASIC design. Besides performance, flex cells can be used for optimizing power, both dynamic as well as static, in ASICs. Moreover, flex cells naturally fit into the methodology of creating variations of custom transistor topology, for example, the use of a ground gating transistor for leakage power control.14 ■

References 1. D. Chinnery and K. Keutzer, Closing the Gap between ASIC & Custom, Kluwer Academic Publishers, 2002. 2. Collett International, “1999 IC/ASIC Functional & Timing Verification Study,” 1999; www. Collett.com. 3. R.B. Hitchcock, “Timing Verification and Timing Analysis Program,” Proc. 19th Design Automation Conf., IEEE CS Press, 1982, pp. 594-604. 4. J.L. Burns and J.A. Feldman, “C5M–A Control-Logic Layout Synthesis System for High-Performance Microprocessors,” IEEE Trans. Computer-Aided Design of Integrated Circuits and Systems, vol. 17, no. 1, 1998, pp. 14-23. 5. University of California, Berkeley, SIS Abstract Page; www.eecs.berkeley.edu/IPRO/Software/Catalog/ Description/sis1.2.html. 6. M.R.C.M. Berkelaar and J.A.G. Jess, “Technology Mapping for Standard-Cell Generators,” Proc. Int’l Conf. Computer-Aided Design, IEEE CS Press, 1988, pp. 470-473. 7. K. Taki, “A Survey for Pass-Transistor Logic Technologies—Recent Research and Developments and Future Prospects,” Proc. Asia-South Pacific Design Automation Conf., IEEE CS Press, 1998, pp. 223226. 8. R.E. Bryant, “Graph-Based Algorithms for Boolean Function Manipulation,” IEEE Trans. Computing, Aug. 1986, pp. 677-691. 9. C.P. Liu and J.A. Abraham, “Transistor-Level Synthesis for Static Combinational Circuits,” Proc. 9th Great Lakes Symp. VLSI, IEEE CS Press, 1999, pp. 172-175. 10. M. Cirit and P. Hurat, “Automated Cell Optimization,” Numerical Technologies white paper, 2002; www.synopsys.com/products/ntimrg/abstracts/ AutomatedCellOptimization.html.

11. A. Reis et al., “The Library Free Technology Mapping Problem,” Proc. Int’l Workshop Logic Synthesis, 1997, IEEE CS Press, pp. 102-106. 12. S. Bodapati and F.N. Najm, “Prelayout Estimation of Individual Wire Lengths,” IEEE Trans. VLSI Systems, vol. 9, no. 6, 2001, pp. 943-958. 13. N. Sherwani, Algorithms for VLSI Physical Design Automation, 2nd ed., Kluwer Academic Publishers, 1995. 14. M. Johnson, D. Somasekhar, and K. Roy, “Leakage Control with Efficient Use of Transistor Stacks in Single Threshold CMOS,” Proc. 36th Design Automation Conf., ACM Press, 1999, pp. 442-445.

Rob (Rabindra) Roy is vice president of marketing and business development at Zenasis Technologies. His research interests include VLSI design and test, timing and power optimization, and wireless communication and computing systems. Roy received a PhD in electrical and computer engineering from the University of Illinois at Urbana-Champaign. Contact him at [email protected]. Debashis Bhattacharya is the chief technology officer and cofounder at Zenasis Technologies. His research interests include CAD for digital VLSI design, high-performance design, and design for test. Bhattacharya received a PhD in computer engineering from the University of Michigan. Contact him at [email protected]. Vamsi Boppana is vice president of engineering and cofounder at Zenasis Technologies. His research interests include all aspects of VLSI design, test, and verification. Boppana received a PhD in electrical and computer engineering from the University of Illinois at Urbana-Champaign. Contact him at [email protected].

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COVER FEATURE

Hardware/Software Interface Codesign for Embedded Systems Separate hardware- and software-only engineering approaches cannot meet the increasingly complex requirements of embedded systems. HW/SW interface codesign will enable the integration of components in heterogeneous multiprocessors. The authors analyze the evolution of this approach and define a long-term roadmap for future success.

Ahmed A. Jerraya TIMA Laboratory

Wayne Wolf Princeton University

0018-9162/05/$20.00 © 2005 IEEE

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n embedded computing system is an application-specific electronic subsystem that is used in a larger system such as a consumer appliance, medical device, or automobile. Embedded systems can embody complete system functionality in several ways—for example, by using software running on CPUs or in specialized hardware accelerators. Technological evolution—particularly shrinking silicon fabrication geometries—is enabling the integration of complex platforms in a single system on chip (SoC). In addition to specific hardware subsystems, a modern SoC also can include one or several CPU subsystems to execute software and sophisticated interconnects. Mastering the design of these embedded systems is a challenge for both system and semiconductor houses that used to apply a software- or hardwareonly strategy. In addition to classic software and hardware, SoC engineers must design hardwaredependent software and software-dependent hardware. Codesigning these HW/SW interfaces requires a new kind of engineer who understands both hardware and software design. Ninety percent of new application-specific integrated circuits (ASICs) fabricated using 130-nm technology already include a CPU,1 and 65-nm

SoCs with more than 100 processors could become commonplace by 2007. Multimedia platforms such as Nomadik and Nexperia are examples of multiprocessor SoCs that use digital signal processors, microcontrollers, and other kinds of programmable processors.2 These systems exploit heterogeneous cores to meet tight performance and cost constraints. As the trend of building heterogeneous multiprocessor SoCs accelerates, they will be composed of multiple, possibly highly parallel processors for use in applications such as mobile terminals, set-top boxes, and game, video, and network processors. To facilitate communication, these chips will also contain sophisticated networks-on-chips (NoCs). Providing SoCs consisting of an assembly of processors executing tasks concurrently will require design methodologies to focus on selecting and using either programmable or dedicated processors in place of the gates and arithmetic logic units that current methods use. Compared with conventional ASIC design, such a multiprocessor SoC requires a fundamental change in chip design.

MULTIPROCESSOR PLATFORMS Application requirements force today’s system designers to develop specific platforms for different design spaces. Some have speculated that the semi-

Published by the IEEE Computer Society

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SW tasks SW adaptation (OS/drivers) CPU subsystem

HW/SW interface SW tasks

HW adaptation

HW subsystems

HW subsystem

(a)

(b)

Figure 1. Evolution of interface-based design. (a) Current methodology prevents designing the software until the hardware platform design is complete. (b) HW/SW interface codesign requires abstract models of both types of components.

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conductor industry is moving toward a universal chip that will provide all the computation power that all applications require. This solution should be developed when it becomes feasible; using a standard platform is likely to become the preferred option because it would eliminate the cost and effort required to build specific HW/SW platforms. However, due to many factors, it is likely that SoC designs will use multiple platforms in the foreseeable future. It is possible to build one or more platforms that effectively provide the basis for many products within a particular application space—such as Texas Instruments’ TI-OMAP and STElectronics’ Nomadik for mobile terminals, and Philips’ Nexperia for digital TV.2 However, enhancing such hardware platforms for use across multiple applications is not viable because they must meet several stringent design constraints simultaneously: hard real-time performance, low power consumption, and low cost. Under these circumstances, the platform must be specialized to exploit a given application’s characteristics. Further, applications that have different combinations of requirements demand multiple architectures. For example, although AVC/H.264 is a common standard for video compression, different types of video compression systems require different platforms. The computation complexity required for video compression in digital cinema and highdefinition video (HDV) cameras is more than 32 tera instructions per second. A cell phone with a video camera uses much smaller frames and lower frame rates, which requires less computation but imposes more stringent power consumption requirements. Because cell phones must also be more physically compact than high-end video cameras, they require more highly integrated architectures. Thus, even this one application can require different platforms. HDV recording illustrates the need for heterogeneous platforms. Assume that the design uses a pure software approach with a SoC platform consisting of programmable processors. To meet the computation requirements, the SoC platform requires 32,000 RISC processors running at 1 GHz.

In the foreseeable future, such a SoC platform may not be realizable in terms of either chip area or power consumption. Such a platform has a significant limitation in terms of power consumption because it would require numerous transistors, and the leakage current—which is proportional to the number of devices—would dominate power consumption. However, when implemented as a mixed HW/SW design, the same MPEG-2 encoder would require only a four-processor solution for a digital cinema application.3

INTERFACE-BASED DESIGN For quite some time, Moore’s law has driven advances in chip density that far outpace advances in designer productivity. To get back on track, designers must work at higher levels of abstraction. The productivity of a designer who can generate only 100 lines of Hardware Description Language (HDL) code per day is higher if those lines represent large blocks rather than logic gates. SoC design generally requires developing complex software, entailing hundreds of thousands of lines of code, to run on the SoC platform. The designer must accomplish this work while balancing the competing constraints of a short time-to-market window and ever-increasingly complex functionality. Scaling current ASIC design approaches to such highly parallel multiprocessor SoCs is difficult, and using classic methods to design these new systems would result in unacceptable realization costs and delays. These constraints are pushing SoC design toward an interface-based methodology that takes advantage of intellectual property.

Current design methodology Traditional ASIC designers have a hardware-centric view of the system design problem. Similarly, software designers have a software-centric view. SoC designs require creating and using radical new design methodologies because some of the key problems in SoC design lie at the boundary between hardware and software. As Figure 1a shows, a SoC can include specific hardware subsystems and one or several CPU subsystems to execute software. The design includes a hardware adapter—a bridge or communication coprocessor—to connect the CPU subsystems to the other subsystems. Each CPU subsystem includes a register transfer level (RTL) or gate model of the CPU and a set of peripherals connected using the CPU bus. In the final design, the system compiles and represents software as binary code that it can load in

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Embedded software

Application software Platform API

A new approach Concurrent HW/SW design requires abstract models of both types of components, as Figure 1b shows. Ideally, the design process would start with a set of software tasks communicating with a set of hardware subsystems. Because software components run on processors, the abstraction needed to describe the interconnection between the software and hardware components is totally different from the existing abstraction of wires between hardware components as well as the function call abstraction that describes the software. The HW/SW interface abstraction must hide the CPU, a hardware module that executes a software program. On the software side, the abstraction hides the CPU under a low-level software layer ranging from basic drivers and I/O functionality to sophisticated operating systems and middleware. On the hardware side, the interface abstraction hides CPU bus details through a hardware adaptation layer generally called the CPU interface. This can range from simple registers to sophisticated I/O peripherals including direct memory access queues and complex data conversion and buffering systems. This heterogeneity complicates designing the interface and makes it time-consuming because it requires knowledge of both hardware and software and their interaction. Consequently, HW/SW interface codesign remains a largely unexplored noman’s-land. General-purpose computer system designers must also consider both hardware and software, but the two are more loosely coupled than in SoC

HW interfaces System interconnect (system bus or network on chip)

Embedded system

CPU subsystem

Execution platform

Hardware-dependent software HW/SW interfaces

the CPU subsystem’s memory. The current SoC design process uses separate teams working serially to create the hardware and software designs. The first step consists of designing the hardware and validating it through RTL simulation using classic HDL simulators, which are much too slow to handle the embedded CPUs. Using a CPU instruction-set simulator can accelerate this simulation. Instruction-set simulators can use a cosimulation backplane to connect to the HDL simulator.4 The next step involves testing an operating system or middleware on the hardware platform and then porting the software to the OS or middleware. Thus, the software design team can begin only after the hardware platform design is complete. This often leads to poor hardware designs because problems caught during software development cannot be fixed in the platform. It also means that the design process takes far too long.5

Figure 2. Embedded system architecture. In addition to hardware, a SoC includes classic application software and hardware-dependent software that must be codesigned with hardware interfaces.

HW interfaces HW component

design. Consequently, general-purpose systems typically model HW/SW interfaces twice: once to test the hardware design and the second time to validate software functionality. Using two separate models induces a discontinuity that wastes design time and results in less efficient, lower-quality hardware and software. This overhead in cost and reduced efficiency are unacceptable for SoC design. Efficiently combining hardware and software to share a single interface requires a new type of HW/SW designer.5

LINKING INTERFACES TO EMBEDDED SOFTWARE Some designers use the term “embedded software” to designate any software in an embedded system, while others use it to mean only that part of the software that is intimately related to hardware—for example, the hardware team generally designs low-level software functions such as drivers and interrupt management. The generic architecture shown in Figure 2 helps to clarify the relationship between hardware and software. An embedded system is an applicationspecific HW/SW architecture. Ideally, the application is a body of software to be executed on a hardware platform. The SoC platform itself also includes, in addition to hardware, a software layer called hardware-dependent software that must be codesigned with hardware interfaces. From the software application point of view, the reaction time is measured in milliseconds; at that execution rate, the platform can be abstracted as an application programming interface or programming model. The API hides hardware details such as interrupt controllers or memory and I/O systems. Software designers develop the application software and use real-time techniques to validate the software application properties.6 February 2005

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There is a temptation to continue using the traditional software- or hardware-only approach to implement large applications.

The hardware-dependent software supports the API, adapting it to the CPU subsystem. The CPU subsystem can hide the complex architecture it generally requires to meet performance demands. In addition to the classical CPU, the subsystem can include sophisticated I/O and memory subsystems. The SoC can include several heterogeneous subsystems, including specific hardware components and sophisticated interconnects. When the subsystems and interconnect designs are decoupled, hardware interfaces are required to adapt them in the final SoC. Both application software and hardwaredependent software may be distributed over different subsystems. To design the application software, classical realtime software designers can use specific analysis tools that support complexity. The hardware-dependent software adapts the application software to a CPU subsystem. In general-purpose computer systems, this layer can use standard components, such as an operating system or middleware, that can be ported to different hardware platforms. When applied to a SoC, however, this solution induces significant overhead in code size, runtime, energy consumption, and other system costs. Two factors cause this overhead. The operating system and middleware must be ported from a uniprocessor platform to heterogeneous multiprocessor platforms. The systems also must implement full-featured functionality to support various types of embedded software. A similar distinction exists on the hardware side, where part of the design depends on software and must be isolated.

HARDWARE/SOFTWARE INTERFACE CODESIGN High-performance embedded systems consist of multiple HW/SW subsystems, with application software tasks distributed over heterogeneous processor subsystems using sophisticated interconnects. The HW/SW interface and the CPU subsystems must handle the interaction between software tasks and the interconnect structure. The interface provides the application software layer with an abstraction of the SoC architecture, called a parallel programming model. It also includes a network interface for both multiprocessor booting and interprocessor communication that connects the subsystem to the network. When the SoC includes more than one CPU, HW/SW interface design becomes more complicated. Parallel programming models are more complex than 66

uniprocessor programming models; similarly, network interfaces are more complex than a unified memory. Thus, as a recent multiprocessor SoC case study confirms,3 the HW/SW interface could become a key challenge in heterogeneous SoC design.

Bridging the gap Because design teams traditionally have applied a software- or hardware-only strategy, there is a temptation to continue using this approach to implement large applications. Software teams claim that their approach results in a shorter design cycle. For example, a pure software approach may reduce the design cycle for derivative design because software is flexible enough to add new functionality. On the other hand, hardware teams argue that their approach is more efficient. While an embedded software approach could result in a larger chip or even a chipset, the ASIC approach will yield a smaller chip. Even for a single product, achieving the best volume in a given market window considering chipsize and yield in chip production may require combining hardware and software solutions. In terms of yield in chip production, both ASIC and embedded software approaches have pros and cons. The ASIC approach can suffer from low yield in the first few months of chip production until the learning curve improves. However, the reduced chip size may improve total chip production. An embedded software approach can give a good initial yield since it reuses an already proven SoC platform. However, a larger chip size may reduce the effects of yield improvement. Ultimately, achieving optimal SoC production will require some combination of hardware and software solutions. Figure 3 shows a simplified flow of concurrent HW/SW design. This codesign scheme opens the design process to several optimizations that are not possible using the classic approach in which hardware and software are designed separately. The most obvious improvement is better adaptation of the CPU to both hardware and software interfaces. For example, designers can use new flexible processor technologies such as Tensilica7 to optimize performance at the HW/SW interface by introducing application-specific I/O operation. In addition, using reconfigurable hardware, such as the Xilinx Virtex II Pro, can optimize hardware interfaces to an embedded CPU.

Interface codesign roadmap The complexity of the HW/SW codesign process will depend on the abstraction level at which the

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Figure 3. HW/SW interface codesign flow. This scheme enables optimizations that cannot be achieved using separate hardware- and software-only approaches.

System specification

Architecture exploration

SW module specification

Embedded software design

Abstract HW/SW interface model • API for SW modules • Abstract interfaces for HW modules • QoS specification

HW module specification

HW/SW codesign • CPU subsystem design • HW-dependent SW design • SW-dependent HW design

Hardware module design

Back-end and hardware prototypes

Embedded system

process starts. Researchers2,8,9 have clearly identified five abstraction levels that will constitute key milestones for future HW/SW codesign automation. Explicit interfaces. The currently used model for SoC design describes hardware as RTL modules. The CPU acts as the HW/SW interface, and designers use explicit memory and I/O architectures to detail the software down to assembly code or lowlevel C programs. Data transfer. At this level, the CPU is abstract. Hardware and software modules interact by exchanging transactions through an explicit interconnect structure, a model generally referred to as transaction-level modeling. Among the various TLM languages, most were developed using SystemC.4 In addition to designing interfaces for different hardware modules, refining a TLM model requires designing a CPU subsystem for each software subsystem. Synchronization. At this level, the interconnect and synchronization are abstractions. The hardware and software modules interact by exchanging data following well-defined communication protocols. The Message Passing Interface (MPI)8 is an example of this approach. Refining an abstract HW/SW interface model requires first designing the interconnect—a system bus or NoC—and then correcting the synchronization schemes. Data transfer must also be refined down to the RTL. Communication. At this level, the communication protocol is abstract. The hardware and software modules interact by exchanging abstract data with-

out regard to the protocol used or the synchronization and interconnect the design will implement. The design typically uses the Specification and Description Language8 to abstract communication. Refining an SDL model requires first selecting a communication protocol—for example, message passing or shared memory—and then following the refinement steps used in lower abstraction levels. Partitioning. The ultimate abstraction level is the functional model in which hardware and software are not partitioned. Designers can use a variety of models to abstract HW/SW partitioning, including sequential programming languages such as C/C++, concurrent languages, and higher-level models such as algebraic notation—for example, the B language. Refining such a model requires first separating the software and hardware functions and then performing the refinements used in higher abstraction levels.

Toward full codesign The ultimate goal is to design both hardware and software at all abstraction levels. Figure 4 details one such full codesign scheme. Traditional codesign research has concentrated on HW/SW partitioning, but without solving the problem of abstracting the hardware platform. Rather than using ad hoc hardware models, SoC designs demand a well-thoughtout approach to the HW/SW interface. The next steps in automation would be data transfer synthesis, synchronization and interconnect, communication, and HW/SW partitioning. February 2005

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Figure 4. Full HW/SW interface codesign scheme: (a) explicit interfaces, (b) data transfer, (c) synchronization, (d) communication, and (e) partitioning.

f1

(e) f 3

(d)

HW/SW partitioning

f2 Embedded software f1 f2

Hardware f3

Platform API

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HW/SW communication protocol synthesis

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OPPORTUNITIES AND CHALLENGES

Early verification

Successful HW/SW interface codesign will fundamentally improve the SoC design process by increasing both hardware and software quality and reliability and by enabling early verification, reusability, and interoperability. It will also provide opportunities for tackling a number of technical challenges confronting embedded-system designers.

Verifying the interface independent of its context is not sufficient—the interface must be verified relative to a given hardware platform. It is not possible to delay performing this verification until the hardware prototype is available. Abstracting the HW/SW interface model will make it possible to verify the interface abstract design itself without using the physical prototype.

Improved software quality Embedded software relies on the hardware platform to support complex quality-of-service (QoS) requirements and ensure reliability. Current practice is to use an existing OS or middleware to validate the nonfunctional properties of application software. Because these generally support real-time and delay requirements but not nonfunctional properties such as intersubsystem communication, bandwidth, jitter, and reliable communication, they cannot systematically monitor and guarantee QoS. In this scenario, it is even difficult to guarantee the reliability of the HW/SW interface design itself. Overcoming this challenge requires a QoS-aware HW/SW interface abstraction. 68

Reusability Mastering embedded system design requires using an efficient method to configure and optimize the HW/SW interface. Using a general HW/SW interface model makes it possible to reuse application software, hardware components, and platform and middleware modules across different products, product families, and even application domains. However, a drawback of generality is inefficiency. For applications that require only a small subset of the complete HW/SW interface functionality, a generic model imposes tremendous overhead that cost-sensitive applications cannot tolerate. A highly configurable and parameterized abstract interface

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architecture enables designers to optimize and streamline an instance of the interface to a given application’s particular needs.

Interoperability Creating abstract HW/SW interfaces facilitates dialogue between design teams that can belong to different companies or even market sectors.10 For example, an automaker could use a standard interface HW/SW API to develop the car’s software while reserving the right to select the hardware platform as late as possible.

he key issue when integrating the parts of an embedded system is the creation of a continuum between the hardware and software, which requires new technologies to effectively integrate components. For example, most conventional parallel programming models—including MPI, the open specifications for multiprocessing (OpenMP), the bulk synchronous parallel (BSP) model, and LogP—are designed for general-purpose computing. SoC APIs must specify application-specific design constraints—for example, in terms of energy consumption, runtime, cost, and reliability. In addition, abstract HW/SW interface models are widely available for single-processor subsystems and homogeneous multiprocessors, but SoCs involve complex interactions between heterogeneous subsystems. Abstracting multiprocessor platforms require a scalable, configurable interface architecture. Embedded computing applications often combine several different kinds of algorithms. Specializing cores by operation type would provide substantial savings in cost and power consumption. Embedded applications also show wide variations in data loads during execution. Flexible networks would allow using interconnect resources more efficiently. Finally, using reconfigurable fabrics as embedded system components would make it possible to target a platform to far more products. ■

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Acknowledgments The authors thank all the members of TIMA’s System-Level Synthesis Group, especially Sungjoo Yoo, Wander Cesário, and Xi Chen, for their help in preparing this article.

References 1. H. Jones, “Analysis of the Relationship between EDA Expenditures and Competitive Positioning of IC Ven-

dors for 2003,” Int’l Business Strategies, 2002; www. edac.org/downloads/04_05_28_IBS_Report.pdf. 2. A.A. Jerraya and W. Wolf, Multiprocessor Systemson-Chips, Morgan Kaufmann, 2004. 3. H. Iwasaki et al., “Single-Chip MPEG-2 422P@HL CODEC LSI with Multi-Chip Configuration for Large-Scale Processing beyond HDTV Level,” Proc. Design, Automation and Test in Europe Conf. and Exhibition (DATE 03 Designers’ Forum), IEEE CS Press, 2003, p. 20,002. 4. SystemC Transaction Level Modeling Working Group, www.systemc.org/projects/tlm. 5. M-W. Youssef et al., “Debugging HW/SW Interface for MPSoC: Video Encoder System Design Case Study,” Proc. 41st Design Automation Conf. (DAC 04), IEEE CS Press, 2004, pp. 909-913. 6. J.W.S. Liu, Real-Time Systems, Prentice Hall, 2000. 7. C. Rowen, Engineering the Complex SoC: Fast, Flexible Design with Configurable Processors, Prentice Hall, 2004. 8. D.B. Skillicorn and D. Talia, “Models and Languages for Parallel Computation,” ACM Computing Surveys, vol. 30, no. 2, 1998, pp. 123-169. 9. W. Wolf, Computers as Components: Principles of Embedded Computing System Design, Morgan Kaufmann, 2001. 10. S. Yoo and A.A. Jerraya, “Introduction to Hardware Abstraction Layers for SoC,” Proc. Design, Automation and Test in Europe Conf. and Exhibition (DATE 03), IEEE CS Press, 2003, pp. 10,336-10,337; http:// sigda.org/Archives/ProceedingArchives/Date/papers/ 2003/date03/pdffiles/04e_1.pdf.

Ahmed A. Jerraya leads the System-Level Synthesis Group at TIMA (Techniques of Informatics and Microelectronics for Computer Architecture) Laboratory in Grenoble, France. His research interests include embedded computing, flexible multiprocessor SoCs, hardware-dependent software, and computer-aided design. Jerraya received a PhD in computer sciences from the University of Grenoble. He is a member of the IEEE and the ACM and is a board member of the European Design Automation Association. Contact him at ahmed. [email protected]. Wayne Wolf is a professor in the Department of Electrical Engineering at Princeton University. His research interests include embedded computing, multimedia systems, VLSI, and computer-aided design. Wolf received a PhD in electrical engineering from Stanford University. He is a Fellow of the IEEE and the ACM. Contact him at [email protected]. February 2005

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R ESEA R C H FEAT URE

A New Framework for Power Estimation of Embedded Systems A proposed modular framework for assessing power consumption of embedded systems early in the design cycle can be extended to any performance metric and uses a high level of abstraction, leading to a faster execution time. Experimental results indicate that the approach is within 20 percent of gate-level estimation and executes three orders of magnitude faster.

Claudio Talarico Jerzy W. Rozenblit University of Arizona

Vinod Malhotra University of Hawaii at Manoa

Albert Stritter Infineon Technologies AG

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he overall goal of system design is to minimize development time and costs, subject to various performance and functionality constraints. To cope with the rapidly growing complexity of embedded systems, designers must work at higher levels of abstraction.1 Depending on the abstraction layer—the level of detail used to describe the system—designers can address different concerns. The key is to model the system at each abstraction layer with as little detail as possible and then collect performance metrics that help the development team make sound engineering decisions. Among the many metrics used to characterize the quality of an embedded system-on-chip (SoC) design, power consumption has emerged as one of the most important. This is largely due to the proliferation of mobile battery-powered computing devices, the increasing speed and density of CMOS (complementary metal-oxide semiconductor) VLSI (very large-scale integration) circuits, and continuous shrinking of the transistor feature size of deepsubmicron technologies.2 Designers can estimate power consumption at four different abstraction levels: • Circuit-level approaches simulate the circuit at the transistor or switch level and monitor the supply current.3

0018-9162/05/$20.00 © 2005 IEEE

• Logic-level techniques simulate a design at the logic-gate level and calculate power by considering the switching activity and node capacitance. Logic-level approaches execute orders of magnitude faster than circuit-level approaches but at the expense of accuracy.4 • Register-transfer-level approaches5 model the power consumption of more abstract components such as muxes, adders, multipliers, and registers. They have satisfactory accuracy (5-10 percent of gate-level power estimates), but their computational time, while orders of magnitude smaller than with logic-level approaches, is too slow when applied to large designs. • System-level approaches6 estimate power consumption based on simple high-level descriptions of the system’s behavior and its intended application, using an abstract notion of capacitance and switching. Different estimation techniques are best suited to different parts of a design or different stages in the design flow. We have developed a technique that derives power figures from the execution of high-level models rather than gate- or transistor-level precharacterizations. This technique makes it possible to assess embedded SoC designs much earlier in the design cycle, contributing to sounder decisions

Published by the IEEE Computer Society

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Figure 1. Power estimation framework. The framework acts as a generic wrapper around the system components, each of which has an associated simulation model and monitor. The monitor observes the model’s execution and probes the data needed to characterize the component’s behavior. Power analyzers then compute the performance indices of interest.

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throughout the entire development process and leading to a faster execution time. To validate our methodology, we applied it to a peripheral core—a baud rate generator—and compared the results with those obtained using a gatelevel approach.

POWER CONSUMPTION MODELS Researchers have developed several techniques for estimating software power consumption for microprocessor and digital signal processor cores, mainly at the instruction level.2,7,8 Given a program execution trace, this approach computes the energy that each executed instruction consumes. Energy consumption depends on the specific instruction being executed as well as on previously executed instructions and on the data on which the instruction operates. This process can be accelerated by deriving a trace file of reduced size that generates equal power dissipation.9 Other researchers have explored software power optimization techniques.10 In addition, a proposed mathematical model of a generic 32-bit processor, obtained through functional decomposition, classifies instructions based on the functional units exercised.11 This model estimates the static power consumption of the single instructions executed, but 72

it does not consider the dynamic power information associated with the actual applied input data. Another technique estimates power consumption of peripheral cores.12 Finally, a number of proposed system-level models for cache, memory, and bus power consumption consist mainly of closed-form equations that express power consumption as a function of usage/traffic and component parameters.13-15 All of these system-level techniques use gate- or transistor-level precharacterizations, which require detailed knowledge of the components’ internal structure, to develop energy consumption models. However, such information may not be available early in the design process, or IP providers may not want to disclose it. In addition, a given application’s power consumption provides little information about the power consumption of other applications for the same system. Consequently, characterization-based power models are highly accurate only if evaluated in the same context as that used for characterization.

POWER ESTIMATION FRAMEWORK Figure 1 illustrates our proposed framework for estimating the power consumption of a generic embedded system. The framework functions as a

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generic wrapper around the system components, each of which has an associated simulation model and monitor. The monitor observes the model’s execution and probes the data needed to characterize the component’s behavior. Various power analyzers then compute the performance indices of interest. Our framework generalizes and extends the schema developed by Tony Givargis, Frank Vahid, and Jörg Henkel.12 The key difference is that our framework does not rely on gate-level simulation to characterize each core’s per-instruction power consumption. In our view, a core’s behavior can be seen as the execution of a sequence of instructions, in which the term “instruction” is synonymous with “action” and is not necessarily atomic. The framework’s distinguishing feature is its modularity, which helps isolate the various system components from one another and to abstract their implementation details. This makes it possible to assess designs early in the process, when the impact of decisions is critical to avoid expensive and timeconsuming iterations. The modeling concepts’ generality also extends our framework beyond power consumption for use in evaluating other performance metrics.

System power consumption Our framework consists of four steps that lead to an estimate of overall system power consumption: • translating each core’s functionality to a set of primitive instructions, • simulating the application program, • mapping the instructions requested by the application program into abstract functional units, and • computing aggregate power consumption of the entire system. The first step consists of breaking each core’s functionality into a set of instructions. A component’s functionality represents all possible behaviors it can assume, with behavior meaning the set of actions that the component performs during execution of an application. The goal is to devise a high-level executable model of the core that can output power consumption data during system simulation. This first step hides the complexity of the core’s internal implementation behind the simple interface offered by the instruction set. There is a tradeoff in selecting the right set of instructions: Having many fine-grained instructions can lead to greater

accuracy, but it requires a longer simulation time than having fewer coarse-grained The framework’s instructions.12 The framework associates modularity makes it with each core’s instruction set only the inforpossible to assess mation needed to describe the performance designs early in the metric of interest—in this case, power consumption. process, when the The second step involves simulating the impact of decisions application program and extracting a trace is critical to avoid file for the core. A trace is the sequence of expensive and instructions/data items a core executes during its simulation. The aim is to estimate the time-consuming core’s switching activity. iterations. The third step consists of mapping the instructions requested by the various tasks performed by the core into abstract functional units that are used to estimate complexity— that is, gate count. Given switching activity and complexity, the framework can compute the core’s power per instruction. The fourth step involves connecting all the core models to compute the power consumption of the entire system.

Power analyzer modules Each of the power analyzer modules shown in Figure 1 embodies the analytical expressions needed to compute the power consumed by the various types of cores: processor, cache, main memory, bus, and peripherals. The input of the power estimation flow is the application program, which feeds into the target CPU’s instruction set simulator (ISS) to produce a program trace. A software power analyzer then postprocesses the program trace to estimate the power the processor consumes during software execution. The application program also feeds into a memory trace profiler, which records all memory access traces and then calculates the number of cache demand misses for both data and instructions. The software power analyzer uses this information to account for additional power consumption due to cache-miss stalls. The main memory power analyzer and cache power analyzer also use this data to compute the power consumption of the main memory and cache accesses. Depending on whether peripherals are accessed through memory-mapped or dedicated I/O, it is possible to extract a peripheral access trace from either the memory access traces or program traces. Any access to or from main memory, caches, and peripherals translates eventually into information traffic over the communication buses. Specific bus February 2005

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The framework models the peripheral in terms of a set of instructions and a set of power modes.

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power analyzers compute the power that each bus in the system consumes.

Component power consumption Because gate-level representation of most cores may not be available early in the design process, our framework computes power dissipation analytically, combining the technology parameters obtainable from data sheets with the data gathered by executing the core’s high-level model. The framework uses ad hoc correction methods to evaluate the power consumed by nonlinear components. A typical example is the interaction between cache and processor. In this case, it is necessary to first evaluate processor power consumption by assuming the ideal case in which all instructions and data can be retrieved from the cache and then account for the energy penalty caused by the processor stalling due to read or write misses in the data cache and fetch misses in the instruction cache. Processor. Our framework relies on an ISS to estimate the power the CPU consumes to execute the application software. The ISS maintains detailed statistics of the processor’s internal activity—such as fetches, stalls, instruction execution frequency, and internal register accesses—that the software power analyzer can postprocess to compute power consumption. This technique is an extension of earlier instruction-based approaches.2,12 The idea behind such approaches is that “by measuring the current drawn by the processor as it repeatedly executes certain instructions, it is possible to obtain most of the information that is needed to evaluate the power cost of a program for that processor.”2 Cache. To estimate cache energy consumption, we adapted analytical models developed by Milind Kamble and Kanad Ghose.13 Accurate estimation requires that the cache simulator maintains activity statistics for several metrics including number of hits and misses, number of tag comparisons, word-line activity, and bit-line activity. The major components of energy consumption are in the bit lines, word lines, output lines, and input lines: Ecache = Ebitline + Ewordline + Eoutput + Einput. The energy dissipated in other cache components such as comparators, registers, data steering logic, control logic, and sense amplifiers is relatively small and can be neglected. Main memory. To compute the energy that main memory consumes, our framework uses the analytical models described by Kiyoo Itoh.14 The main sources of power dissipation are the memory cell

array, row decoder, column decoder, and periphery circuits. Bus. In deep-submicron technologies, bus power is a significant part of total power. Execution time and bus power are inversely related: A smaller bus width implies less wire capacitance and hence less power, but it requires more bus transfers and hence a longer execution time. Every memory and peripheral access implies a data transfer over a communication bus. The total number of cache accesses Nacc measures traffic on the CPU-cache bus, the number of cache misses Nmiss measures traffic on the cache-main memory bus, and the number of peripheral references Nper measures traffic on the peripheral bus—the bus between main memory and the peripheral devices. Given this traffic and assuming that on average at most half of the bits will toggle, our framework can then compute bus switching activity. It uses this value and bus capacitance to compute power consumption. Peripherals. For a processor, the term “instruction” generally means an atomic action for programming the desired behavior. However, for a peripheral, an instruction is an action that, together with all other instruction set actions, describes the peripheral’s functionality.12 Our framework models the peripheral in terms of a set of instructions and a set of power modes. Power modes take into account that certain instructions can significantly change power consumption. The framework follows a four-step procedure to obtain peripheral power consumption. First, it profiles the application program for requests to and from the peripheral. The number and frequency of peripheral accesses is a measure of its switching activity. Second, it decomposes the various types of tasks requested into instructions and maps them into abstract functional units for use in estimating complexity. Given switching activity and complexity, the framework then creates a power-perinstruction lookup table. Third, the framework executes the peripheral model to generate the corresponding trace. Finally, given the instructions trace, it uses the power-per-instruction lookup table to compute power consumption.

EXAMPLE SIMULATION To validate our system-level approach, we used SystemC to model a baud generator unit that clocks the universal asynchronous receiver/transmitter inside the Infineon XC161CJ microcontroller. Embedded systems are inherently heterogeneous— they consist of an intricate intermix of both hard-

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Prescaler

Enable

Select

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Figure 2. Baud generator architecture and power model. (a) The baud generator consists of a prescaler containing a selectable fractional divider and two fixedinteger dividers, a 13-bit timer, and an output stage providing the baud rate. (b) Each state represents a power mode, and the transition from state to state depends on the instructions from the application program.

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ware and software components. Using the same high-level language to describe both hardware and software makes the modeling task easier. As Figure 2a shows, the baud generator consists of three functional units: a prescaler containing a selectable fractional divider and two fixed-integer dividers, a 13-bit timer, and an output stage providing the baud rate. Modeling power consumption requires only a small amount of detail. As Figure 2b illustrates, our framework uses a finite state machine to describe power behavior. Each state represents a power mode, and the transition from state to state depends on the instructions from the application program. The total energy that the baud generator consumes during execution of the application program is given by N

Ebg = Tclock ×

∑ (n

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cyc, j

× pinst, j

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=

∑ (T

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j = 1

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pinstr, j =

NF 1 × Vdd2 × ∑ Ck × α k , j 2 k = 1

where Vdd is the power supply voltage, NF is the number of functional units composing the baud gen-

erator, Ck is the total capacitance of functional unit k, and αk,j is the switching activity occurring within the functional unit k to execute instruction j.

Experimental setup To test our approach, we implemented a systemlevel model of the baud generator. The model represents the peripheral module of the power estimation framework shown in Figure 1. We used the C++ language—the availability of SystemC makes this an ideal match for a unified HW/SW framework. The baud generator model includes only the power behavior. To achieve good accuracy, we used a state machine to express each instruction’s dependency on the previous ones, with the instructions triggering transitions from one state to the other. To compute the power per cycle of each core’s instruction, we employed Infineon’s 0.25-µm CMOS technology. We estimated the average capacitance of combinational cells and sequential cells separately, averaging the intrinsic capacitance of cells in the target technology, and stored the resulting values in a lookup table to facilitate access during model execution. Figure 3a shows implementation details of our framework’s peripherals module. The design explorer analyzes the functional units forming the various components, estimates their complexity (total capacitance) based on the target technology, and evaluates each unit’s power consumption. The application profiler parses the application program and extracts the instructions that affect the peripherals and distributes them accordingly. February 2005

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Gate-level design Application program

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ε Figure 3. Two approaches to measuring power consumption in a baud generator. (a) System-level approach. (b) Gate-level approach.

Different models and monitors are associated with different peripherals or various refinements of the same peripheral. The monitors observe the associated models’ execution and characterize their power behavior. The power analyzer collects the information that the monitors capture and computes power consumption. A distinguishing feature of our system-level approach is that it does not require gate-level synthesis and simulation. However, to validate its effectiveness and efficiency, we compared our results against those obtained using gate-level power estimation, as shown in Figure 3b. The experiments consisted of running 20 randomly generated application programs for 2,000 clock cycles. To perform a comparative analysis, we used a VHSIC Hardware Description Language model of the baud generator implemented at the register transfer level and then used Synopsys tools to synthesize it down to the gate level. To perform the gate-level power estimation, we used Synopsys power-estimation tools and a set of VHDL test benches generated by replicating the application programs.

consistently lower than gate-level estimation because the former always considers a lower level of detail than the latter. Power consumption underestimation represents a serious problem in scenarios that focus on worst-case design analysis rather than design tradeoffs. Profiling energy consumption is particularly useful to gain insight into system hot spots. Figure 5a shows the energy the system consumes while executing three of the benchmarked application programs. Figure 5b shows a scatter plot of the power that all 20 benchmarks dissipated over 2,000 cycles. The average error is less than 20 percent, and the standard deviation is 8.26 percent. Each point on the scatter plot depicts a benchmark’s average power. The abscissa represents the average power obtained using our system-level approach, while the ordinate represents the average power obtained using the gate-level technique. If there was no difference between the two methods, all dots would lie on the solid line. Compared to gatelevel power estimation, our approach achieves a speedup of 1,343—three orders of magnitude faster.

Experimental results Figure 4 summarizes the power per cycle dissipated by each instruction using both approaches. The average error is 9.71 percent, and the standard deviation is 9.36 percent. System-level estimation is 76

he primary goal of our approach is to make power-related system-level design decisions as early as possible in the design cycle. Therefore, 20 percent accuracy can be considered satisfactory

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Figure 4. Power per cycle dissipated by each instruction. System-level estimation is consistently lower than gate-level estimation.

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and, in fact, may be the only viable alternative when gate-level or transistor-level precharacterization is impossible. Indeed, at this level, the key is to provide fidelity—a high percentage of correctly predicted comparisons between design implementations—rather than very high estimation accuracy. Future work will include validation on largerscale designs and iterative refinements of the models based on earlier results. We also plan to extend the framework to as many performance indices as

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possible including response time, throughput, chip area, software size, and production costs. ■

References 1. A. Sangiovanni-Vincentelli and G. Martin, “Platform-Based Design and Software Design Methodology for Embedded Systems,” IEEE Design & Test of Computers, Nov./Dec. 2001, pp. 23-33. February 2005

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2. V. Tiwari, S. Malik, and A. Wolfe, “Power Analysis of Embedded Software: A First Step toward Software Power Minimization,” IEEE Trans. VLSI Systems, Dec. 1994, pp. 437-445. 3. S.M. Kang, “Accurate Simulation of Power Dissipation in VLSI Circuits,” IEEE J. Solid-State Circuits, Oct. 1986, pp. 889-891. 4. T.H. Krodel, “PowerPlay—Fast, Dynamic Power Evaluation Based on Logic Simulation,” Proc. 1991 IEEE Int’l Conf. Computer Design: VLSI in Computers & Processors (ICCD 91), IEEE CS Press, 1991, pp. 96-100. 5. S. Ravi, A. Raghunathan, and S. Chakradar, “Efficient RTL Power Estimation for Large Designs,” Proc. 16th Int’l Conf. VLSI Design (VLSI 03), IEEE CS Press, 2003, pp. 431-439. 6. M. Nemani and F.N. Najm, “High-Level Area and Power Estimation for VLSI Circuits,” IEEE Trans. CAD of Integrated Circuits and Systems, June 1999, pp. 697-713. 7. R.Y. Chen, M.J. Irwin, and R.S. Bajwa, “Architecture-Level Power Estimation and Design Experiments,” ACM Trans. Design Automation of Electronic Systems, Jan. 2001, pp. 50-66. 8. A.C.S. Beck et al., “CACO-PS: A General-Purpose Cycle-Accurate Configurable Power Simulator,” Proc. 16th Symp. Integrated Circuits and Systems Design (SBCCI 03), IEEE CS Press, 2003, pp. 349354. 9. C-T. Hsieh et al., “Profile-Driven Program Synthesis for Evaluation of System Power Dissipation,” Proc. 34th Design Automation Conf., IEEE CS Press, 1997, pp. 576-581. 10. V. Dalal and C.P. Ravikumar, “Software Power Optimizations in an Embedded System,” Proc. 14th Int’l Conf. VLSI Design (VLSI 01), IEEE CS Press, 2001, pp. 254-259. 11. C. Brandolese et al., “Static Power Modeling of 32Bit Microprocessors,” IEEE Trans. CAD Integrated Circuits and Systems, Nov. 2002, pp. 1306-1316. 12. T. Givargis, F. Vahid, and J. Henkel, “InstructionBased System-Level Power Evaluation of System-ona-Chip Peripherals Cores,” IEEE Trans. VLSI Systems, Dec. 2002, pp. 856-863. 13. M.B. Kamble and K. Ghose, “Energy-Efficiency of VLSI Caches: A Comparative Study,” Proc. 10th Int’l Conf. VLSI Design: VLSI in Multimedia Applications (VLSI 97), IEEE CS Press, 1997, pp. 261-267. 14. K. Itoh, “Trends in Low-Voltage Embedded-RAM Technology,” Proc. 23rd Int’l Conf. Microelectronics (MIEL 02), IEEE Press, 2002, pp. 497-501. 15. W. Fornaciari, D. Sciuto, and C. Silvano, “Power Estimation for Architectural Exploration of HW/SW Communication on System-Level Buses,” Proc. 7th

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Int’l Workshop Hardware/Software Co-Design (CODES 99), IEEE CS Press, 1999, pp. 152-156.

Claudio Talarico is a research assistant professor in the Electrical and Computer Engineering Department at the University of Arizona. His research interests include design methodologies for integrated circuits and systems with emphasis on system-level design, embedded systems, HW/SW codesign, low-power design, system specification languages, and early design assessment, analysis, and refinement of complex SoCs. Talarico received a PhD in electrical engineering from the University of Hawaii at Manoa. He is a member of the IEEE Computer Society. Contact him at claudio@ece. arizona.edu.

Jerzy W. Rozenblit is a professor and heads the Electrical and Computer Engineering Department at the University of Arizona. His research interests are in the areas of complex systems design and simulation modeling. Rozenblit received a PhD in computer science from Wayne State University. He is a senior member of the IEEE Computer Society and the ACM. Contact him at [email protected].

Vinod Malhotra is an associate professor in the Department of Electrical Engineering at the University of Hawaii at Manoa. His research interests include wet and dry processes for passivation of GaAs and InP surfaces and surface-sensitive devices, such as HBTs, MSM photodetectors, and VCSELs. Malhotra received a PhD in electrical engineering from Colorado State University. He is a member of the American Vacuum Society, the Electrochemical Society, and the IEEE. Contact him at [email protected].

Albert Stritter is vice president of design automation at Infineon Technologies AG in Munich, Germany. His research focuses on all aspects of electronic design automation and technology integration. Stritter received an MS in electrical engineering from the Università degli Studi di Genova. He is a member of the Virtual Socket Interface Alliance and EDA (Electronic Design Automation) Zentrum, Hannover, Germany. Contact him at [email protected].

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PRODUCTS

Network Test Accepts Data Traffic Developers can use Scalable Network Technologies’ latest software release, QualNet 3.8, to design and test a wide variety of communication networks, including ad hoc wireless networks. The new Real-Time Interfaces Module directly supports hardwareand software-in-the-loop simulation by accepting packet data traffic from a real network. QualNet 3.8 also includes a new 3D GUI for realistic visualizations. The new release features more than a dozen new network models, including a model for background traffic and randomly occurring interface faults; www.scalable-networks.com.

Feedthrough Filters Reduce Noise AVX Corporation’s new series of feedthrough filters offers automotive engineers a way to significantly reduce noise in digital circuits up to 5 GHz. The W2F4 and W3F4 feedthrough arrays contain four elements with a common ground connection for multiline designs. The capacitor provides low parallel inductance and offers excellent broadband EMI attenuation for all circuitry in need of passing SAE, FCC, and IEC EMC requirements. Applications include data lines to dashboard and diagnostic units, as well as RGB lines to LCD displays within entertainment centers such as DVD players or GPS units; www. avxcorp.com.

tection option, eliminating the need for an extra protection diode. Other key features include a 2.7 V to 7.5 V VIN range, a 1.25-MHz constant-switching frequency, and input undervoltage protection. The LM3557 converter is available in an eight-lead LLP package and costs 96 cents in 1,000-unit quantities; www.national.com.

Advanced Web-Browsing Technology Lonopono is a new client-side Webbrowsing technology designed to collect, organize, share, and display information from Web pages as well as other sources such as RSS feeds, photos, videos, OPML lists, and documents. Lonopono runs on any platform, including Windows, Mac OS X, Linux, and Unix, and it includes an integrated knowledge base (using the Web Ontology Language) and advanced scripting support. The beta version of Lonopono, available in Standard, Professional, and Power User versions, is free; www. lonopono.com.

WinWedge Pro Gets Upgrade TAL Technologies has released version 3.1 of its data collection program, WinWedge Pro, designed to interface RS232 and TCP/IP devices to any Windows application. Different instruments can simultaneously send data to different applications or “fields” within the same application. The new version supports 32-bit features such as preemptive multitasking, up to 100 com ports simultaneously, and up to 56,000-baud data rates, and it is 30 percent faster than 16-bit versions. Users can now resize the “Analyze” window as well as leave it open while defining the structure of incoming serial data, add a delay between keystrokes sent to other programs, or minimize WinWedge to the system tray instead of the taskbar. They also can send keystrokes to DOS programs or other Windows applications that do not respond to keyboard input. WinWedge Pro v3.1 costs $159 for owners of previous versions; www. taltech.com.

LM3557 Can Drive Up to Five LEDs in Series National Semiconductor’s LM3557, a fixed-frequency current-mode stepup DC-DC converter, is suitable for white-LED applications. An external feedback resistor sets a constant current through the LEDs. The LM3557 can drive up to five LEDs in series with a 20-mA current and has a fixed 24-V overvoltage proPlease send new product announcements to [email protected].

Scalable Network Technologies’ QualNet 3.8 includes a new 3D GUI for realistic visualizations of communication networks. Published by the IEEE Computer Society

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BOOKSHELF

orensic Discovery: The Definitive Guide to Computer Forensics, Dan Farmer and Wietse Venema. This book covers both the theory and hands-on practice of forensic discovery, introducing a powerful approach that can often recover evidence considered forever lost. The authors draw on firsthand experience to cover subjects ranging from file systems to memory and kernel hacks to malware. They expose a wide variety of computer forensics myths that often stand in the way of success. Readers will find extensive examples from Solaris, FreeBSD, Linux, and Microsoft Windows as well as practical guidance for writing their own forensic tools. This book can help readers understand essential forensics concepts such as volatility, layering, and trust; gather the maximum amount of reliable evidence from a running system; recover partially destroyed information and make sense of it; and timeline their system to understand what really happened and when. Readers will also learn how to uncover secret changes to everything from system utilities to kernel modules, avoid cover-ups and evidence traps set by intruders, and identify the digital footprints associated with suspicious activity. Other topics covered include understanding file systems from a forensic analyst’s point of view, analyzing malware without giving it a chance to escape, capturing and examining the contents of main memory on running systems, and how to unravel an intrusion one step at a time. A companion Web site contains complete source and binary code for the open source software the authors describe. The site also offers additional computer forensics case studies and resource links. Addison-Wesley Professional; www. awprofessional.com; 0-201-63497-X; 240 pp.; $39.99.

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ractical Software Testing: A Process-Oriented Approach, Ilene Burnstein. Software testing is rapidly evolving as a critical software engi-

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neering subdiscipline. To meet the needs of software professionals in this field, the author explains how to effectively plan for testing, design test cases, test at multiple levels, organize a testing team, and optimize testing tool use. Using the Testing Maturity Model as a framework, the book introduces testing in a systematic, evolutionary way; describes industrial TMM applications; and covers testing topics with either procedurally based or objectoriented programming code. The book includes a sample test plan, comprehensive exercises, and definitions for software testing and quality. It introduces both technical and managerial aspects of testing in a clear and precise style and provides a balanced perspective of all aspects of testing. Springer; www.springeronline.com; 0-387-95131-8; 706 pp.; $69.95. nternet Denial of Service: Attack and Defense Mechanisms, Jelena Mirkovic, Sven Dietrich, David Dittrich, and Peter Reiher. This book sheds light on a complex form of computer attack that impacts the confidentiality, integrity, and availability of millions of computers worldwide. It tells the network administrator, corporate chief technical officer, incident responder, and student how hackers prepare and execute distributed denial of service attacks, how to think about DDoSs, and how to arrange computer and network defenses. It also provides a suite of actions that can be taken before, during, and after an attack. The book gives readers comprehensive information on how denial-of-

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service attacks are waged, how to improve a network’s resilience to denialof-service attacks, what to do when targeted by a denial-of-service attack, and the laws that apply to these attacks and their implications. It also describes how often denial-of-service attacks occur and the kind of damage they can cause and provides real examples of denial-of-service attacks as experienced by the attacker, victim, and unwitting accomplices. Prentice Hall PTR; www.phptr.com; 400 pp.; 0-13-147573-8; $39.99. utonomy Oriented Computing: From Problem Solving to Complex Systems Modeling, Jiming Liu, XiaoLong Jin, and Kwok Ching Tsui. This book provides a comprehensive reference for scientists, engineers, and other professionals concerned with this promising development in computer science. It can also be used as a text in graduate and undergraduate programs in computer-related disciplines, including robotics and automation, amorphous computing, image processing, and computational biology. In addition to describing the basic concepts and characteristics of an autonomy-oriented computing system, the book enumerates the critical design and engineering issues faced in AOC system development. The authors offer detailed analyses of methodologies and case studies that evaluate AOC’s use in problem solving and complex system modeling. The book’s many illustrative examples, experimental case studies, and exercises at the end of each chapter help consolidate the methodologies and theories presented. Kluwer Academic Publishers; www. wkap.nl; 1-4020-8121-9; x pp.; $136.

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Editor: Michael J. Lutz, Rochester Institute of Technology, Rochester, NY; mikelutz@mail. rit.edu. Send press releases and new books to Computer, 10662 Los Vaqueros Circle, Los Alamitos, CA 90720; fax +1 714 821 4010; [email protected].

Published by the IEEE Computer Society

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COMPUTER SOCIETY CONNECTION

2005 Class of IEEE Fellows Announced he IEEE Board of Directors recently conferred the title of Fellow upon 268 senior members of the IEEE, including 44 Computer Society members. The IEEE’s practice of naming Fellows dates back to 1912: The constitution of the American Institute of Electrical Engineers, a progenitor of the IEEE, included procedures for selecting Fellows. Today, Fellow status recognizes a person who has established an extraordinary record of achievements in any of the IEEE fields of interest. Senior IEEE members have already demonstrated outstanding achievement in engineering.

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A Robert Thomas Harold Alden, McMaster University, for contributions to eigenvalue analysis of power system stability. (Power Engineering) Minoru Asada, Osaka University, for contributions to robot learning and applications. (Robotics and Automation) B Dines Bjorner, University of Denmark, for contributions to formal methods software development and its applications in industry. Duane S. Boning, Massachusetts Institute of Technology, for contributions to modeling and control in semiconductor manufacturing. (Electron Devices) C Roy H. Campbell, University of Illinois at Urbana-Champaign, for contributions to concurrent programming, system software, security, and ubiquitous computing.

IEEE policy limits the total number of Fellows selected in any one year to one-tenth of one percent of the IEEE’s total voting membership. With IEEE membership going strong at more than 359,000 professionals, this year’s Fellows class is smaller and more elite than the policy mandates. The Computer Society members whose names appear below are now

Francky Catthoor, Interuniversity Microelectronics Center, for contributions to data and memory management for embedded systemon-chip applications. (Circuits and Systems) Chang Wen Chen, Florida Institute of Technology, for contributions to digital image and video processing, analysis, and communication. (Circuits and Systems) Yung-Chang Chen, National Tsing Hua University, for contributions to low-bit-rate modeling-based coding. (Circuits and Systems) Alok Nidhi Choudhary, Northwestern University, for contributions to high-performance computing systems. Edmund Melson Clarke, Carnegie Mellon University, for contributions to model-checking methods for formal verification. Thomas M. Conte, North Carolina State University, for contributions to computer architecture, compiler code generation, and performance evaluation.

Published by the IEEE Computer Society

IEEE Fellows, effective 1 January. An accompanying citation details the accomplishments of each new Fellow. In cases where a Computer Society member has been named a Fellow based upon contributions to a field other than computing, the name of the evaluating IEEE society appears after the citation. Two IEEE members with no society affiliation were named 2005 Fellows for their contributions to computing: John Millar Carroll, Pennsylvania State University, for contributions to humancomputer interaction methods and science; and Charles E. Stroud, Auburn University, for contributions to the built-in self-test of integrated circuits.

F Jeanne Ferrante, University of California, San Diego, for contributions to optimizing and parallelizing compilers. H Glenn Edward Healey, University of California, Irvine, for contributions to the modeling and processing of multispectral and hyperspectral images. Michael N. Huhns, University of South Carolina, for contributions to artificial intelligence applications in distributed computational environments. J Jing-Yang Jou, National Chiao Tung University, for contributions to the computer-aided design of digital circuits. K Mohamed Kamel, University of Waterloo, for contributions to pattern recognition and intelligent sys-

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tems. (Systems, Man, and Cybernetics) Willis K. King, University of Houston, for contributions to computer science and engineering education. Fadi Joseph Kurdahi, University of California, Irvine, for contributions to design automation of digital systems and to reconfigurable computing. (Circuits and Systems) L Bruce Gilbert Lindsay, IBM Research, for contributions to the technologies of relational database systems. William Peter Loftus, Gestalt LLC, for leadership in the development of middleware for interoperability of large complex software systems. (Engineering Management) Ronald Lumia, University of New Mexico, for leadership in the development of open-architecture control systems for applications in robotics and automation. (Robotics and Automation) M Anthony A. Maciejewski, Colorado State University, for contributions to the design and control of kinematically redundant robots. (Robotics and Automation) Bangalore S. Manjunath, University of California, Santa Barbara, for contributions to the research and standardization of face animation and object-based video coding. (Signal Processing) James Randal Moulic, IBM Research, for leadership in the advancement of technology and architecture of personal and highperformance computing systems. N Paul Nikolich, Lynnfield, Massachusetts, for leadership in enabling ubiquitous broadband Internet access and associated standards.

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O Mohammad S. Obaidat, Monmouth University, for contributions to adaptive learning, pattern recognition, and system simulation. (Systems, Man, and Cybernetics) Jorn Ostermann, University of Hannover, for contributions to research and standardization of face animation and object-based video coding. (Signal Processing)

Tokyo, for contributions to highperformance computation models. Fred James Taylor, University of Florida, for contributions to highperformance digital signal processing. (Signal Processing) Shoji Tominaga, Osaka ElectroCommunication University, for contributions to the analysis of physical phenomena in digital color imaging.

P Hoang Pham, Rutgers University, for contributions to analytical techniques for modeling the reliability of software and systems. (Reliability) Rosalind Wright Picard, Massachusetts Institute of Technology, for contributions to image and video analysis and affective computing.

U Javier Uceda, Polytechnic University of Madrid, for contributions to the development of switched-mode power supplies. (Industrial Electronics)

R Daniel A. Reed, University of North Carolina, for contributions to high-performance computing. Johan H. C. Reiber, Leiden University, for contributions to medical image analysis and its applications. (Engineering in Medicine and Biology) Christian Roux, National School of Telecommunications, France, for contribution to the theory of functional shapes and its applications in medical imaging. (Engineering in Medicine and Biology) S Bjarne Stroustrup, Texas A&M University, for contributions to the creation of the C++ programming language and its applications. Richard Szeliski, Microsoft Research, for contributions to image-based modeling and rendering, and Bayesian and optimization-based techniques in computer vision. T Hidehiko Tanaka, University of

V Adrianus Johannes Vinck, University of Essen, for contributions to coding techniques. (Information Theory) W Lois D. Walsh, US Air Force, for leadership in electronic device reliability. (Reliability) Paul B. Wesling, Saratoga, California, for contributions to multimedia education development within IC packaging. (Components, Packaging, and Manufacturing) Donald Coolidge Wunsch, University of Missouri, for contributions to hardware implementations of reinforcement and unsupervised learning. (Neural Networks) Y Kazuo Yano, Hitachi Research, for contributions to nanostructured silicon devices and circuits and to advanced CMOS logic. (SolidState Circuits) Z Zhengyou Zhang, Microsoft, for contributions to robust computer vision techniques.

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IEEE Fellow Nominations Due 1 March Leonard L. Tripp, Chair, 2005 Computer Society Fellows Nomination Committee he IEEE and its member societies cooperate each year to select a small group of outstanding professionals for recognition as IEEE Fellows. A senior IEEE member who has achieved distinction in his or her field can be named an IEEE Fellow only after being nominated for the honor. All such nominations undergo rigorous review before the IEEE Board of Governors votes on bestowing the prestigious rank of Fellow. To nominate a candidate for IEEE Fellow recognition, begin the process by visiting www.ieee.org/fellows/. The Electronic Fellow Nomination Process is detailed at http://elektra.ieee.org/ Fellows/FellowNo.nsf. The deadline for 2006 Fellow nominations is 1 March. In the event that the online nomination process is unsuitable, paper nomination materials can be obtained from the IEEE Fellow Committee, 445 Hoes Lane, PO Box 1331, Piscataway, NJ 08855-1331; voice +1 732 562 3840; fax +1 732 981 9019. Hard copies may also be obtained by request from [email protected]. Nominators should avoid submitting the forms via fax.

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Nominators A nominator need not be an IEEE member. However, nominators cannot be IEEE staff or members of the IEEE Board of Directors, the Fellow Committee, the technical society, or council evaluation committee.

Preparing a nomination Essential to a successful nomination is a concise account of a nominee’s accomplishments, with emphasis on the most significant contribution. The nominator should identify the IEEE

society or council that can best evaluate the nominee’s work and must send the nomination form to the point of contact for that group. For the IEEE Computer Society, the point of contact is Lynne Harris, whose address appears at the end of this article. Careful preparation is important. Endorsements from IEEE entities such as sections, chapters, and committees and from non-IEEE entities and non-IEEE individuals are optional but may be useful when these entities or individuals are in the best

IEEE Computer Society Press Considers Editor in Chief Shafer for Reappointment The IEEE Computer Society Press, the nonperiodical publishing arm of the IEEE Computer Society, is considering the reappointment of its current editor in chief, Don Shafer. Shafer is a cofounder, director, and chief technology officer of the Athens Group, an employee-owned technology and software consulting firm. He has also developed hardware and software products for Motorola, Advanced Micro Devices, and Crystal Semiconductor. Shafer is a senior member of the IEEE and an adjunct professor of software engineering at Texas State University. To provide feedback on Shafer’s contributions to the IEEE Computer Society Press, please e-mail comments to Deborah Plummer at [email protected].

Nominees A nominee must be a senior member at the time of nomination and must have been an IEEE member in any grade for the previous five years. This includes exchange, student, associate, member, senior, and honorary member, as well as the life category of membership. It excludes affiliates, however, because this category does not comprise IEEE members. The five-year requirement must be satisfied at the date of election, 1 January 2006; thus, a nominee must have been in any member grade continuously since 31 December 2000. The five-year membership requirement may be waived in the case of nominees in Regions 8, 9, and 10. Fellows are never named posthumously.

Computer Society Staffers Receive Harry Hayman Awards At a recent meeting in New Orleans, the IEEE Computer Society Board of Governors honored both Computer Society publisher Angela Burgess and continuing education coordinator Stacy Saul with 2004 Harry Hayman Distinguished Service Awards. Burgess was recognized for her many years of outstanding work on Computer Society publications. Saul was honored for her outstanding work in support of the Computer Society International Design Competition and for her leadership on the Certified Software Development Professional initiative. Honorees receive a plaque and a $5,000 honorarium in recognition of “long and distinguished service of an exemplary nature in the performance of duties over and above those called for as a regular employee of the Society.” The Hayman Award is the highest service award given to an active member of the Computer Society staff. Award criteria and a list of previous winners are available at www.computer.org/awards/.

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Computer Society Connection

position to provide credible statements.

References The nominator should select references who are familiar with the nominee’s contributions and can provide insights into these achievements. For nominees in the US and Canada, references must be from IEEE Fellows;

outside the US and Canada, senior members can provide references if necessary. References cannot be from the IEEE staff or members of the IEEE Board of Directors, the Fellow Committee, the technical society, or council evaluation committee. While a minimum of five references are needed, it is strongly recommended that the maximum of eight be sought.

Grant Funds Available for Educational Projects To advocate for and support wide-reaching educational projects in fields of IEEE interest, the IEEE Foundation each year awards several generous grants. The IEEE Foundation, an independent philanthropic body, was established in 1973 “exclusively to support the scientific and educational purposes of the IEEE.” The Foundation is now soliciting proposals for grant funds to be distributed later this year. The Foundation bestows program grants and subsidies that support education, history, and other special initiatives. Proposals must meet a number of criteria. The proposed project must promise to improve education in mathematics, science, and technology from precollege through continuing education; preserve, study, or promote the history of IEEE-associated technologies; recognize major contributions to these technologies; or provide a major contribution to communities served by the IEEE. Guidelines on applying for a 2005 IEEE Foundation grant are available at www.ieee.org/foundation. Early 2005 grant proposals are due by 15 April. For consideration later in 2005, proposals are due by 16 September.

Past recipients At its November 2004 meeting, the IEEE Foundation awarded two new education grants totaling $50,000. One $25,000 grant will fund the 2005 IEEE Sections Congress, a triennial gathering of hundreds of delegates from all 10 regions of the IEEE. The Foundation also awarded a two-year, $25,000 grant to the IEEE’s emeritbadges.org, an international preuniversity technology education program for boys and girls. Other grant recipients recognized in 2004 included the IEEE Nigeria Section, which received $24,400 for “Networking Nigeria.” This project supplements a Hewlett-Packard Foundation-funded computer lab at the University of Ibadan and two years of complimentary access to IEEE Xplore by providing Internet access and a lab coordinator. In addition, Rutgers University received $10,000 in support of “Edison Across the Curriculum,” an educational project that is integrating documents from Rutgers’ Thomas A. Edison Papers collection into a preK-12 multiplesubject curriculum. A full list of the grants awarded in 2004 is available at www.ieee.org/ organizations/foundation/html/2004grants.html. The IEEE Computer Society International Design Competition is also a past recipient of IEEE Foundation funds. The CSIDC program, which provides undergraduate students a start-to-finish real-world hardware and software engineering challenge, received $50,000 in support of its 2003 and 2004 competitions.

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Evaluation of nominees The IEEE Fellow Committee considers the following criteria: • individual contributions as an engineer or scientist, technical leader, or educator; • technical evaluation by one IEEE society or council; • tangible and verifiable evidence of technical accomplishment, such as technical publications, patents, reports, published product descriptions, and services, as listed on the nomination form; • confidential opinions of referrers who can attest to the nominee’s work; • IEEE and non-IEEE professional activities, including awards, services, offices held, committee memberships, and the like; and • total years in the profession.

Resubmission of nominations Typically, less than half of the nominations each year are successful. Therefore, highly qualified individuals may not succeed the first time. Because reconsideration of a nominee is not automatic, nominators are encouraged to update and resubmit nominations for unsuccessful candidates. To resubmit these materials, ensure that the nomination forms are current. The deadline for resubmission is the same as for new nominations.

Nomination deadline The IEEE Fellow Committee must receive 2005 nomination forms by 1 March. The staff secretary must also receive at least five Fellow-grade reference letters directly from the referrers by that date. In addition, the evaluating society or council must also receive a copy of the nomination by 1 March. The deadline will be strictly enforced. If the evaluation is to be conducted by the Computer Society, send a copy, preferably via e-mail, to Lynne Harris, IEEE Computer Society, 1730 Massachusetts Ave. NW, Washington, DC 20036-1992; voice +1 202 371 0101; fax +1 202 728 9614; l.harris@ computer.org. ■

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Computer Society Announces 2005 Meetings and Election Schedule ecently, the IEEE Computer Society released its official 2005 administrative schedule. The three administrative meeting series of the Society’s governing boards provide focal points for other deadlines. Groups that are scheduled to meet during the weeklong sessions include the Chapters Activities Board, the Publications Board, and the Electronic Products and Services Board. Also noted are deadlines for both Computer Society and IEEE election materials.

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2005 ELECTION The 2005 calendar includes significant dates in the 2005 election cycle. The 4 October election will name the 2006 first and second vice presidents; the 2006 president-elect, who will serve as president in 2007; and seven members of the Board of Governors, who serves three-year terms. Officers elected in the 2005 elections begin their terms on 1 January 2006. Nomination recommendations for candidates in this year’s election must be received by the Nominations Committee no later than 10 May. Recommendations must be accompanied by the nominee’s biographical information, which should include facts about past and present participation in Society activities. Nomination materials should be sent to Carl K. Chang, Nominations Committee Chair, IEEE Computer Society, 1730 Massachusetts Ave. NW, Washington, DC 20036-1992; voice +1 202 371 0101; fax +1 202 296 6896; c.chang@ computer.org.

2005 SCHEDULE Member participation and volunteer involvement are welcomed throughout the year. The following calendar highlights dates of note for the Society.

11 March: Computer Society Board of Governors Meeting, Portland, Oregon. Culminates weeklong administrative meetings series for Society governing boards. 10 May: The Nominations Committee sends its slate of officer and board candidates to the Board of Governors. 21 May: Deadline for recommendations from membership for board and officer nominees to be mailed to Nominations Committee. 31 May: Last day to send candidates’ petitions, signed by members of the 2005 Board of Governors, to Stephen B. Seidman, Society Secretary, IEEE Computer Society, 1730 Massachusetts Ave. NW, Washington, DC 20036-1992; voice +1 202 371 0101; fax +1 202 296 6896; s.seidman@ computer.org. 10 June: Computer Society Board of Governors Meeting, Long Beach, California. Culminates weeklong administrative meetings series for Society governing boards. 10 June: Last day to submit 2007 IEEE delegate-director-elect petition candidates to the IEEE. 30 June: Position statements, photos, and biographies of those candidates approved by the Board of Governors are due at the Society’s publications office in Los Alamitos, California, for publication in the September issue of Computer. July: Computer publishes the Boardapproved slate of candidates and a call

for petition candidates for the same officer and Board positions. 31 July: Member petitions and petition candidates’ position statements, biographies and photos due to Society Secretary Stephen B. Seidman at the address above. August: Computer publishes schedule and call for 2006 IEEE delegatedirector-elect recommendations to Nominations Committee. 8 August: Ballots are mailed to all members who are eligible to vote. September: Computer publishes position statements, photos, and biographies of the candidates. 4 October: Ballots from members are received and tabulated. 7 October: The Nominations Committee makes recommendations to the Board of Governors for 2008 IEEE delegate-director-elect. 4 November: Computer Society Board of Governors Meeting, Philadelphia, Pennsylvania. Culminates weeklong administrative meetings series for Society governing boards. 4 November: The IEEE delegatedirector-elect slate is approved by the Board of Governors. December: Computer publishes election results.

Editor: Bob Ward, Computer; [email protected]

RENEW your IEEE Computer Society membership for...

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CALL AND CALENDAR

CALLS FOR IEEE CS PUBLICATIONS An August/September 2005 special issue of IEEE Intelligent Systems aims to bridge the gap between data mining and bioinformatics. The guest editors seek papers that propose novel data mining techniques for challenges in areas that include genomics, proteomics, and metabolomics; the diagnosis, prognosis, and treatment of diseases; drug design; systems biology; and the structure and function of proteins and RNA. The deadline for submitting manuscripts is 7 March. See the full call for papers at www.computer.org/intelligent/ cfp14.htm. IEEE Internet Computing invites contributions for a November/ December 2005 special issue on security for P2P systems and ad hoc networks. Topics include key management, access control, secure MAC protocols, performance and security trade-offs, and denial of service. Manuscripts are due by 1 April. See the complete call at www.computer. org/internet/call4ppr.htm#v9n6. For an October/November 2005 special issue on artificial intelligence and homeland security, IEEE Intelligent Systems is encouraging submissions of practical and novel AI technologies,

Submission Instructions The Call and Calendar section lists conferences, symposia, and workshops that the IEEE Computer Society sponsors or cooperates in presenting. Complete instructions for submitting conference or call listings are available at www.computer. org/conferences/submission.htm. A more complete listing of upcoming computer-related confeences is available at www.computer.org/ conferences/.

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techniques, methods, and systems. Submissions on all research areas relating to both AI and national or homeland security are welcome. Topics include bioterrorism tracking, alerting, and analysis; criminal data mining; deception detection systems; and crime and intelligence visualization. Manuscripts are due by 1 April. See the complete call at www.computer. org/intelligent/cfp16.htm.

OTHER CALLS VL/HCC 2005, IEEE Symp. on Visual Languages & Human-Centric Computing, 21-24 Sept., Dallas, Texas. Papers due 6 Mar. http://viscomp. utdallas.edu/vlhcc05/ HASE 2005, 9th IEEE Int’l Symp. on High-Assurance Systems Eng., 12-14 Oct., Heidelberg, Germany. Papers due 15 Mar. http://hase.informatik. tu-darmstadt.de/submit/ ISESE 2005, ACM-IEEE 4th Int’l Symp. on Empirical Software Eng., 1718 Nov., Noosa Heads, Australia. Papers due 4 Apr. http://attend.it.uts. edu.au/isese2005/cfp.htm ICDM 2005, 5th IEEE Int’l. Conf on Data Mining, 26-30 Nov., New Orleans. Papers due 1 Jun. www.cacs. louisiana.edu/~icdm05/cfp.html

12-16 Mar: IEEE VR 2005, IEEE Virtual Reality Conf., Bonn, Germany. www.vr2005.org/ 14-16 Mar: ASYNC 2005, 11th Int’l Symp. on Asynchronous Circuits & Systems, New York. http://vlsi.cornell. edu/async2005/ 20-22 Mar: ISPASS 2005, IEEE Int’l Symp. on Performance Analysis of Systems & Software, Austin, Texas. http://ispass.org/ 20-23 Mar: CGO 2005, 3rd Ann. IEEE/ACM Int’l Symp. on Code Generation & Optimization, San Jose, Calif. www.cgo.org/ 28-30 Mar: AINA 2005, IEEE 19th Int’l Conf. on Advanced Information Networking & Applications, Taipei. www.takilab.k.dendai.ac.jp/conf/aina/ 2005/ 29-31 Mar: DCC 2005, IEEE Data Compression Conf., Snowbird, Utah. www.cs.brandeis.edu/~dcc/ 29 Mar.-1 Apr: EEE 2005, IEEE Int’l Conf. on e-Technology, e-Commerce, & e-Service, Hong Kong. www.comp. hkbu.edu.hk/~eee05/ 30 Mar.-2 Apr: LATW 2005, 6th IEEE Latin-American Test Workshop, Salvador, Brazil. www.latw.net/

CALENDAR

APRIL 2005

MARCH 2005

3-8 Apr: SEW-29, 29th IEEE/NASA Software Eng. Workshop, Greenbelt, Md. http://sel.gsfc.nasa.gov/

7-10 Mar: RTAS 2005, 11th IEEE Real-Time and Embedded Technology and Applications Symp., San Francisco. www.cis.upenn.edu/rtas05/ 7-11 Mar: DATE 2005, Design, Automation, & Test in Europe, Munich. www.date-conference.com/ 8-12 Mar: Percom 2005, Int’l Conf. on Pervasive Computing & Comm., Koloa, Hawaii. www.percom.org/

4-5 Apr: ECBS 2005, 12th Ann. IEEE Int’l Conf. and Workshop on Eng. of Computer-Based Systems (with SEW29), Greenbelt, Md. http://abe.eng.uts. edu.au/ECBS2005/ 4-8 Apr: ISADS 2005, 7th Int’l Symp. on Autonomous Decentralized Systems, Chengdu, China. http://isads05. swjtu.edu.cn/

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4-8 Apr: IPDPS 2005, Int’l Parallel & Distributed Processing Symp., Denver, Colo. www.ipdps.org/ 5-8 Apr: ICDE 2005, 21st Int’l Conf. on Data Eng., Tokyo. http://icde2005. is.tsukuba.ac.jp/ 6-7 Apr: EDPS 2005, Electronic Design Process Symp., Monterey, Calif. www.eda.org/edps/ 11-13 Apr: ITCC 2005, Int’l Conf. on IT, Las Vegas. www.itcc.info/ 11-14 Apr: MSST 2005, 22nd IEEE Conf. on Mass Storage Systems and Technologies, Monterey, Calif. www. storageconference.org/

18-21 May: ISMVL 2005, 35th Int’l Symp. on Multiple-Valued Logic, Calgary, Canada. www.enel.ucalgary. ca/ISMVL2005/ 22-25 May: ETS 2005, 10th European Test Symp., Tallinn, Estonia. http:// sise.ttu.ee/ati/ETS/ 25-26 May: EBTW 2005, European Board Test Workshop (with ETS 2005), Tallinn, Estonia. www.molesystems. com/EBTW05/ 30-31 May: EMNETS-II 2005, 2nd IEEE Workshop on Embedded Networked Sensors, Sydney, Australia www.cse.unsw.edu.au/~emnet/

JUNE 2005 20-22 Apr: Cool Chips VIII, Int’l Symp. on Low-Power & High-Speed Chips, Yokohama, Japan. www.coolchips.org/

MAY 2005 1 May: DBT 2005, IEEE Int’l Workshop on Current & Defect-Based Testing (with VTS-05), Rancho Mirage, Calif. www.cs.colostate.edu/ ~malaiya/dbt.html 1-5 May: VTS 2005, 23rd IEEE VLSI Test Symposium, Rancho Mirage, Calif. www.tttc-vts.org/ 9-12 May: CCGrid 2005, 5th IEEE Int’l Symp. on Cluster Computing & the Grid, Cardiff, UK. www.cs.cf.ac. uk/ccgrid2005/ 11-13 May: NATW 2005, IEEE 14th North Atlantic Test Workshop, Essex Junction, Vt. www.ee.duke.edu/NATW/ 15-16 May: IWPC 2005, 13th Int’l Workshop on Program Comprehension (with ICSE), St. Louis. www.ieeeiwpc.org/iwpc2005/ 15-21 May: ICSE 2005, 27th Int’l Conf. on Software Eng., St. Louis. www.cs.wustl.edu/icse05/Home/index. shtml

6-8 June: Policy 2005, IEEE 6th Int’l Workshop on Policies for Distributed Systems & Networks, Stockholm. www.policy-workshop.org/2005/ 6-9 June: ICDCS 2005, 25th Int’l Conf. on Distributed Computing Systems, Columbus, Ohio. www.cse. ohio-state.edu/icdcs05/ 12-13 June: MSE 2005, Int’l Conf. on Microelectronic Systems Education (with Design Automation Conf.), Anaheim, Calif. www.mseconference. org/ 13-16 June: ICAC 2005, 2nd IEEE Int’l Conf. on Autonomic Computing, Seattle. www.autonomic-conference. org/ 13-16 June: WOWMOM 2005, Int’l Symp. on A World of Wireless, Mobile, & Multimedia Networks, Taormina, Italy. http://cnd.iit.cnr.it/wowmom2005/ 13-17 June: SMI 2005, Int’l Conf. on Shape Modeling & Applications, Cambridge, Mass. www.shapemodeling. org/ 16-20 June: ICECCS 2005, Int’l Conf. on Eng. of Complex Computer

Systems, Shanghai. www.cs.sjtu.edu. cn/iceccs2005/ 19-24 June: MSST 2005, 2nd Int’l. IEEE Symp. on Mass Storage Systems & Technologies, Sardinia, Italy. www. storageconference.org/ 20-26 June: CVPR 2005, IEEE Int’l Conf. on Computer Vision & Pattern Recognition, San Diego, Calif. www. cs.duke.edu/cvpr2005/ 26-29 June: LICS 2005, 20th Ann. IEEE Symp. on Logic in Computer Science, Chicago. http://homepages. inf.ed.ac.uk/als/lics/lics05/ 27-29 June: ARITH-17, 17th IEEE Symp. on Computer Arithmetic, Cape Cod, Mass. http://arith17.polito.it/ 27-29 June: CollaborateCom 2005, 1st IEEE Int’l Conf. on Collaborative Computing: Networking, Applications, & Worksharing, Cape Cod, Mass. www.collaboratecom.org/ 27-30 June: ISCC 2005, 10th IEEE Symp. on Computers & Communication, Cartagena, Spain. www.comsoc. org/iscc/2005/ 28 June-1 July: DSN 2005, Int’l Conf. on Dependable Systems & Networks, Yokohama, Japan. www.dsn.org/ 30 June-1 July: DCOSS 2005, Int’l Conf. on Distributed Computing in Sensor Systems, Marina del Rey, Calif. www.dcoss.org/

JULY 2005 5-8 July: ICALT 2005, 5th IEEE Int’l Conf. on Advanced Learning Technologies, Kaohsiung, Taiwan. www. ask.iti.gr/icalt/2005/ 6-8 July: ICME 2005, IEEE Int’l Conf. on Multimedia & Expo, Amsterdam. www.icme2005.com/ February 2005

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CAREER OPPORTUNITIES

Tenure Track Position Faculty of Engineering and Computer Science The Department of Computer Science and Software Engineering at Concordia University invites applications for one tenure-track faculty position. We are looking for an excellent candidate in any area of Computer Science or Software Engineering. The rank and salary will be commensurate with qualifications and experience. The new position requires a PhD degree in Computer Science or Software Engineering, or a closely related field, completed or near completion. The department places a strong emphasis on teaching and on fundamental and applied research. For the rank of Assistant Professor we seek primarily candidates who have recently obtained a PhD or who are about to receive it. A publication record or very strong research potential is required, as is strong interest and ability in teaching at the undergraduate and graduate levels. For the rank of Associate Professor, excellent credentials in both research and teaching are required. A successful candidate is expected to contribute to course and laboratory development at all levels of instruction, to be active in research, and to secure external research funding. The department encourages interdisciplinary research partnerships, industrial collaborations, and technology transfer. The department offers Bachelor of Computer Science and Bachelor of Engineering (Software Engineering) programs. The programs are accredited by CSAC and CEAB, respectively. At the graduate level, it offers a Master of Computer Science, a Master of Applied Computer Science, a PhD (Computer Science), and a Postgraduate Diploma in Computer Science. The department houses about 1100 undergraduates and 500 graduate students. The 38 full-time faculty members are assisted by 18 full-time staff members. The Department has a research centre CENPARMI (Centre for Pattern Recognition and Machine Intelligence), is involved in two inter-university research centres (mathematical computing and VLSI architectures), and participates in the Network of Centres of Excellence. The University has several programs to provide seed grants for research in the beginning years. The department is located in downtown Montreal, an exciting and dynamic city noted for fine restaurants, excellent entertainment, and an urban setting with many opportunities for a rich social life. Montreal combines the excitement of a modern, multicultural city with affordable housing and easy access to outdoor activities. It is also noted for its four major universities and more than two hundred local high-tech companies. Montreal is currently enjoying high growth in the software industry's main areas of development, especially in telecommunications, aerospace, software development, and multimedia. Montreal is rapidly gaining a reputation as one of Canada's leading high-tech centres. There is ample opportunity for industrial collaboration. Although the primary language at Concordia University is English, proficiency in French is considered an asset. Interested applicants should send a detailed curriculum vitae, a list of publications, and at least three references to: Prof. C. Lam, Chair Department of Computer Science and Software Engineering Concordia University 1455 de Maisonneuve West Montreal, Quebec H3G 1M8 Canada Tel: (514) 848-2424 ext. 3001 Fax : (514) 848-2830 Email : [email protected] Website : http://www.cse.concordia.ca All qualified candidates are encouraged to apply; however, Canadians and permanent residents will be given priority. Concordia University is committed to employment equity.

WASHINGTON STATE UNIVERSITY. The School of Electrical Engineering and Computer Science at Washington State University invites applications for one tenure-track position in computer science and two in computer engineering at the rank of assistant professor. Applicants must have earned a Ph.D. in computer engineering, computer science, or electrical engineering by August 15, 2005. Candidates must have a strong interest in and a demonstrated capacity to conduct publishable research and must display the potential for successful teaching. A record of publication in refereed journals and conference proceedings is essential. Areas in computer engineering given highest priority will be computer architecture, digital system design, embedded systems, networks, hardware-software codesign, design automation, test and verification, fault tolerance, reconfigurable systems, VLSI design, and nanotechnology. In computer science the highest priority areas will be software engineering, databases, security, networking/distributed systems, and bioinformatics. However, outstanding candidates who have specialized in other areas will also be considered. The successful candidate will be expected to teach, effectively communicate and interact with students and colleagues, conduct funded research, and direct MS and PhD student research programs. WSU is a Carnegie Research I University located in Pullman, a diverse university town near the Washington/Idaho border 75 miles south of Spokane. Pullman is known for its high quality of life, including an excellent K-12 public school system. The region is renowned for its scenic beauty and recreational opportunities. Pullman combines the facilities of a major university with the convenience of a small town to provide a highly productive work environment for its faculty and students. The University of Idaho is located seven miles to the east of WSU. The proximity of these universities ensures an academic and cultural atmosphere which is far more vibrant and stimulating than that of other towns of similar size. WSU's location also facilitates collaboration with Seattle-area companies. Such collaborations are supported financially by the State of Washington through the Washington Technology Center and the Washington Research Foundation. The School of EECS has forty faculty. Research expenditures in the School exceed $3.5 million per year. Research facilities are excellent, including several hundred workstations, high-speed networking, and dedicated laboratory space. The School offers new junior faculty a reduced teaching load for the first three years of their appointment. To learn more about WSU, the School, and faculty research interests, consult http://www. eecs.wsu.edu/. Screening of applications will begin upon receipt and continue until

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the positions are filled. Appointments will start August 16, 2005. Applicants should send a cover letter, a curriculum vitae, and the names and addresses of three references qualified to comment on the applicant's research and teaching qualifications to: Chair, EECS Search Committee, School of Electrical Engineering and Computer Science, Washington State University, P O Box 642752, Pullman WA 99164-2752. WSU is an EO/AA educator and employer.

THE UNIVERSITY OF NEBRASKA AT OMAHA, Tenure Track Assistant Professor or Above, Computer Science Department. Candidates are sought in the following areas: software engineering, network security, parallel and distributed computing, and databases in mobile environment. Exceptional candidates in other areas will also be considered. One of the requirements is an earned doctorate in computer science or a closely related area. Applicants interested in the position are asked to apply on line at: http://careers.unomaha.edu, where the full text of this advertisement can be found. The Information Science

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and Technology (IST) College, which includes the computer science department, is housed in the Peter Kiewit Institute, a new state-of-the-art facility for teaching and research. Financial support of the institute, now exceeding $180M, reflects a unique business-academic partnership. Degrees of B.S., M.S., and Ph.D. are offered. We invite you to visit our website at: http://www.ist.unomaha.edu. The University of Nebraska at Omaha has a commitment to developing and maintaining a diverse faculty and staff and strongly encourages those from underrepresented groups to apply for this position. The University of Nebraska at Omaha is an Affirmative Action/Equal Opportunity employer.

UNIVERSITY OF LOUISIANA AT LAFAYETTE, The Center for Advanced Computer Studies, Faculty Position, Graduate Fellowships. Candidates with a strong research record and an earned doctorate in computer science or computer engineering are invited to apply for a tenure-track assistant professor faculty position starting August 17, 2005. Target areas include Grid Computing,

Visualization, and Distributed Software Systems. Consideration will also be given to outstanding candidates in other areas. The candidate must have demonstrated potential to achieve national visibility through accomplishments in research contract and grant funding, publications, teaching and supervising graduate students. Faculty teach mostly at the graduate-level and offer a continuing research seminar. State and university funds are available to support research initiation efforts. Salaries are competitive along with excellent support directed towards the attainment of our faculty's professional goals. The Center's colloquium series brings many world known professionals to our campus each year. The Center is primarily a graduate research unit of 18 faculty, with programs leading to MS/PhD degrees in computer science and computer engineering. Approximately 220 graduate students are enrolled in these programs, including 80 PhD students. The Center has been ranked 46th in a recent NSF survey based on research and development expenditures, and ranked 35th among the top 100 graduate programs in North America by the Communications of the ACM, based on research publications. The Center has state-of-the-art research and instructional computing facilities, consisting of several networks of SUN workstations and other high performance platforms. In addition, the Center has dedicated research laboratories in Computer Vision and Pattern Recognition, Intelligent Systems, Computer Architecture and Networking, Cryptography, FPGA and Reconfigurable Computing, Internet Computing, Virtual Reality, Software Research, VLSI and SoC, and Wireless Technologies. Related university programs include the CSAB (ABET) accredited undergraduate program in Computer Science, and the ABET accredited undergraduate program in Electrical and Computer Engineering. Additional information about the Center may be obtained at http://www.cacs.louisiana. edu/. A number of PhD fellowships, valued at up to $18,000 per year including tuition and most fees, are available. They provide support for up to four years of study towards the PhD in computer science or computer engineering. Eligible candidates must be U.S. citizens or must have earned an MS degree from a U.S. or Canadian university. Recipients also receive preference of low-cost campus housing. The University of Louisiana at Lafayette is a Research Intensive University, with an enrollment of 16,500 students. Additional information may be obtained at http://www.louisiana.edu/. The University is located in Lafayette, the hub of Acadiana, which is characterized by its Cajun music and food, and joie de vivre atmosphere. The city, with its population of over 120,000, provides many

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recreational and cultural opportunities. Lafayette is located approximately 120 miles west of New Orleans. The search committee will review applications and continue until the position is filled. Candidates should send a letter of intent, curriculum vitae, statement of research and teaching interests, and names, addresses and telephone numbers of at least four references. Additional materials, of the candidate's choice, may also be sent to: Dr. Magdy A. Bayoumi, Director The Center for Advanced Computer Studies, University of Louisiana at Lafayette, Lafayette, LA 70504-4330. Tel: 337.482.6147; Fax: 337.482.5791. The University is an Affirmative Action/Equal Opportunity Employer.

DARTMOUTH COLLEGE, Director of the William H. Neukom Institute of Computational Science. Dartmouth College invites nominations and applications for the position of Director of the William H. Neukom Institute of Computational Science. We seek a prominent scientist whose vision and leadership will establish this interdisciplinary Institute at Dartmouth. Made possible by a generous gift, the William H. Neukom Institute will

strengthen and broaden research in computational science. At the same time it will increase the undergraduate student awareness of and accessibility to computational science across the College. Dartmouth is committed to building a worldclass Institute that will leverage existing efforts on campus. The director will hold a tenured full-professor position in the department of Computer Science. She/he must be a skilled academic administrator who has the vision and ability to position the Institute at the forefront of research and education. In addition to the Director, three new tenure-track faculty positions are available with at least two being in departments other than Computer Science. Resources for undergraduate research, graduate and post-doctoral fellowships, equipment, outreach, and administrative support will be available. With over 4,000 undergraduate and 1,500 graduate students and a tenuretrack faculty of 355 in arts and sciences and 743 in professional schools, Dartmouth College combines the best features of an undergraduate liberal arts college with the intellectual vitality and resources of a research university. This highly selective institution has been a leader of American higher education since 1769. Sixteen graduate programs

are offered in the arts and sciences, and the three professional schools of business, engineering, and medicine. Dartmouth College is committed to diversity and encourages applications from women and minorities. Dartmouth is an Equal Opportunity, Affirmative Action employer. Additional information is available at http://www.dartmouth.edu. All applications, nominations and inquiries should be directed to: Professor Scot Drysdale, Department of Computer Science, Dartmouth College, 6211 Sudikoff Laboratory, Hanover, NH 03755-3510. E-mail: [email protected]. Applicants should send letter of application, a curriculum vitae, a research and a teaching statement, and the names of at least four professional references. Review of applications will begin February 15 and continue until the position is filled.

GANNON UNIVERSITY, Electrical and Computer Engineering Faculty. Gannon University, a Catholic university located in Erie, Pennsylvania, invites applications for a tenure-track assistant professor position in Computer Engineering for Fall 2005. Committed to excellence in teaching, Gannon has a strong relation-

INDIANA UNIVERSITY BLOOMINGTON School of Informatics/Computer Science Tenure-track faculty position in Cybersecurity Starting Fall 2005

The School of Informatics and the Department of Computer Science at Indiana University at Bloomington are expanding their Cybersecurity research team and invite applications for a tenure-track or tenured position starting Fall 2005. Applicants must possess an outstanding record of research and a sincere commitment to teaching. Additionally, a Ph.D. degree or equivalent in computer science or a related discipline is required. Preference will be given to candidates with demonstrated strength in network security but applications from extraordinary candidates in all areas of computing research are welcome. We are going through an exciting growth phase and have recently added 42 tenure-track faculty. With a current combined academic faculty of 62, in the School of Informatics and the Department of Computer Science cover a broad range of research areas. Further, research centers like CACR (Center for Applied Cybersecurity Research) and PTL (Pervasive Technology Labs) support a wide variety of focused as well as collaborative research projects spanning multiple academic units on campus. More information about the School of Informatics can be found at www.informatics.indiana.edu. The department of Computer Science can be visited at www.cs.indiana.edu. Indiana University at Bloomington campus has been named the "most unwired" campus by Intel and among the "most wired" campuses by Yahoo! Internet Life magazine in their surveys, providing excellent facilities for teaching and research. The attractive wooded campus is located in the rolling hills of southern Indiana, only an hour from the Indianapolis airport. Bloomington is a college town with an abundance of cultural and recreational activities and has been chosen as one of the most cultural and livable small cities in the US. We encourage early applications but full consideration will be given to all applications that are received by January 1, 2005. Positions may be filled at any time, but we expect to make most of our hiring decisions by May 1, 2005. Applicants should submit a curriculum vitae, a statement of research and teaching emphasizing informatics and computer science, and 3 reference letters for junior faculty and 6 reference letters for associate and full professors. Applications should be sent to: Faculty Search Committee 901 E. 10th Street Bloomington, Indiana 47408 Or online at: http://www.informatics.indiana.edu/positions/ Indiana University is an Affirmative Action/Equal Opportunity Employer. Applications from women and under-represented minorities are strongly encouraged.

University of Bridgeport Faculty Positions in Electrical/ Computer Engineering and Computer Science The Electrical Engineering and Computer Science and Engineering Departments at the University of Bridgeport invites applications for full time tenure-track positions at the Assistant/ Associate Professor level. Candidates for the tenure-track positions must have a Ph.D. in electrical/computer engineering or computer science. A strong interest in teaching undergraduate and graduate courses and an excellent research record are required. The ability to teach lab-based courses is also required. Applicants are sought in the areas of wireless design, VLSI, communications, FPGA analysis, solid-state electronics, fiber optics, speech analysis, circuit theory, Image Processing, IC Design, Digital and Analog Controls, Medical Electronics, biomedical engineering, biometrics, computer architecture, software engineering, programming, database design, algorithms, e-commerce, data mining, artificial intelligence and data structures. There are opportunities to participate in the external engineering programs, which include weekend and evening graduate and continuing education classes, on-site instruction in local industry and distance learning initiatives. Applicants should send a cover letter, resume and address and e-mail address of four references to: Faculty Search Committee, School of Engineering, c/o Human Resources Department, Wahlstrom Library, 7th Floor, 126 Park Avenue, Bridgeport, CT 06604. Fax: (203) 576-4601. [email protected]. The University of Bridgeport is an equal opportunity, affirmative action employer.

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ship with regional industry. Areas of priority and specialization include object-oriented programming, embedded systems, computer architecture, mixed-signal VLSI circuits and systems; however, exceptional candidates from other areas will be considered. Must be able to support and promote the University’s mission, its Catholic identity, and its liberal arts tradition. Requirements include an earned Ph.D. in Electrical and Computer Engineering or a closely related field. Successful candidates will be expected to provide evidence of outstanding potential in teaching and securing external funding. Submit a cover letter, CV, teaching and research statements, and the contact information for three references to: Gannon University, Engineering Search, 109 University Square, Erie, PA 165410001; Fax to: (814) 871-7514; or Email to: [email protected]. Review of resumes will begin January 31, 2005, and this position will remain open until filled. For more information about Gannon visit www.gannon.edu. Gannon University is an Equal Opportunity Employer that encourages diversity and invites women and underrepresented groups to apply.

TEXAS TECH UNIVERSITY. The Department of Computer Science invites applicants in all areas of Computer Science for a position as the Director of the Abilene Institute and Tenured Professor of Computer Science starting the academic year 2005-06. This position will be at the Texas Tech University graduate campus in Abilene, Texas. The Abilene Institute is dedicated to conducting leading-edge research in computer science and related areas. The Director of the Abilene Institute is expected to lead efforts to secure extramural funding, develop external collaborations, provide the vision and leadership to establish new initiatives and programs, recruit Institute staff, and provide support for Agency Liaison activities. It is critical for the Director to develop relationships with state and federal funding agencies and other government officials. The Professor position provides a synergy between the Institute and the Computer Science Department graduate campus in Abilene. The successful candidate’s academic achievement and professional reputation should be superior and should have resulted in national recognition. The candidate should have an outstanding record of peer-reviewed publications, and funded research. The Computer Science Department in the College of Engineering at Texas Tech University offers a Ph.D., M.S., and B.S. in Computer Science and an M.S. in Software Engineering. The Abilene campus offers only the graduate degrees. We offer competitive salaries, a friendly and cooperative environment, and excellent research facilities. State-of-the-art

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two-way video facilities allow the Lubbock and Abilene sites to exchange course offerings and to conduct collaborative faculty and committee meetings. More information on the department is available at http://www.cs.ttu.edu/. Applicants must have a Ph.D. degree in computer science or a closely related field and should send a curriculum vita, contact information for at least five references, and supporting documents such as statements about past accomplishments in research and leadership. Electronic submission of application materials in PDF is preferred. Electronic submission should be sent to muriel. [email protected] or hardcopy mailed to Dr. Jack A. Barnes, Chair Faculty Search Committee, c/o Ms. Muriel Bockenstedt, Department of Computer Science, Texas Tech University, 302 Pine, Abilene, TX 79601. Review of applications will begin as they are received. Applications will be accepted until the position is filled, assuming the anticipated availability of funds. Candidates must be currently eligible to work in the United States. Texas Tech University is an equal opportunity/affirmative action employer and actively seeks the candidacy of women and minorities.

DRESDEN UNIVERSITY OF TECHNOLOGY, Master of Computer Science (MCS), Dresden, Germany. The computer science department of TU Dresden is a top-tier department in Germany. We offer two International Master Programs in computational engineering and computational logic. As a state supported institution, the tuition for these programs is free! The focus of the computational engineering program is on building software-intensive systems. For more information please see http://www.computa tional-engineering.de.

ILLINOIS INSTITUTE OF TECHNOLOGY, Chicago, IL, Chair, Department of Computer Science. Applications and nominations are invited for the position of Chair of the Department of Computer Science. The candidate’s mission is to lead the department to national prominence, while providing strategic vision, decisive leadership in research and education, and fostering interactions with government and industry. This growing department currently has 17 tenure track faculty members. In the past five years the department has hired ten new faculty – all from top tier CS departments. Research funding has dramatically increased in this time frame and is now close to the funding levels found at top CS departments. New facilities include an 84-node Sun Microsystems ComputeFarm, one 14-node IBM Linux-based clus-

ters, one Cray XD1 parallel computer, and many high-end graphic workstations and servers. The department is connected to and shares advanced computing facilities at the National Center for Supercomputing Applications (NCSA), the Argonne National Laboratory, Northwestern University, the University of Chicago, and the University of Illinois at Chicago via a 7.5million-dollar dedicated 10-gigabit-persecond fiber optic research data network. Several new courses in information retrieval, data mining, and information security have recently been added at the undergraduate level. Faculty research interests include computer networking, distributed and parallel systems, information retrieval and databases, intelligent information systems, and software engineering. The department offers B.S., M.S., and Ph.D. degrees. The department has established cooperative research activities with local research and government agencies. IIT is a private, Ph.D.-granting institution, which offers programs in engineering, science, architecture, psychology, law, and business. The main campus is located within 10 minutes of downtown Chicago. In addition, we have a campus located along the high technology corridor in Chicago's western suburbs. Qualifications for the position include an international reputation in Computer Science, excellent communication and administrative skills, and a desire to take a growing department and continue our long-term goal of transforming it into one of the major centers for CS research in the country. Applications should be sent to: Professor Fouad A. Teymour, Chair, CS Search Committee, 10 W. 33rd Street, Illinois Institute of Technology, Chicago, IL, 60616. http://www.cs.iit.edu. Illinois Institute of Technology is an equal opportunity, affirmative action employer.

KANSAS STATE UNIVERSITY, Faculty Position, Department of Computing and Information Sciences. The department of Computing and Information Sciences at Kansas State University invites applications for a tenure track position beginning in Fall 2005. Preference will be given to candidates in the areas of Bioinformatics data mining, data management, and data integration. Applicants must be committed to both teaching and research. Applicants should have a PhD degree in computer science with demonstrated expertise in Bioinformatics; salary will be commensurate with qualifications. Applications must include descriptions of teaching and research interests along with copies of representative publications. Kansas State University is committed to the growth and excellence of the CIS department. Details of the department can be found at

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http://www.cis.ksu.edu/. Details about Bioinformatics research at K-State can be found at http://www.cis.ksu.edu/bioinformatics. Please send applications to Chair of the Recruiting Committee, Department of Computing and Information Sciences, 234 Nichols Hall, Kansas State University, Manhattan, KS 66506 (email: [email protected]). Review of applications will commence February 1 and continue until the position is filled. Kansas State University is an Affirmative Action Equal Opportunity Employer. The department is committed to diversity, and women and minority candidates are encouraged to apply.

BOISE STATE UNIVERSITY, Assistant Professor, Computer Science Department, College of Engineering, Boise, Idaho 83725-2075. The department has a tenure-track faculty position open for Fall 2005. Screening will begin immediately. Applicants with a Ph.D. in Computer Science are sought, with preference to bioinformatics, systems, databases or graphics (all areas will be considered). Applicants must provide evidence of strong teaching and research potential. Send letter of application, vita, graduate transcripts, and three letters of professional reference to: CS Search Committee, Computer Science Department, Boise State University, Boise, ID 837252075. Boise State University is an EOE/AA Employer. Vets Preferences. For further info, see the website: http://cs.boise state.edu/ad05.html or http://hrs.boise state.edu/joblistings.

SOFTWARE ENGINEER. For company in Littleton, CO, research, design, develop computer software systems in conjunction with product development for engineering, energy-related Ebusiness and geographic information systems for use by telecom companies and/or energy/gas utilities to support a wide range of requirements including outage/distribution management, asset management and mobile workforce management. Design models for spatial data storage and applications to maintain, manage and migrate data to support system operation and provide land information and property data. Implement systems in data relational data stores using Oracle and SQL Server. Design and develop software to retrieve and manipulate spatial data and customize various mapping and geographical web-based applications and/or desktop client/server products, and share this data with other systems using a variety of enterprise integration applications and/or middleware technologies. Analyze software requirements and consult with hardware engineers and other engineer-

ing staff to evaluate interface between hardware and software. Document performance, availability, reliability and extensibility. Formulate and design software system using previous project benchmarks and prototypes. Develop and direct software system testing procedures, programming and documentation. Consult with customer concerning requirements, development, deployment and maintenance of software system. 8am-5pm, 40 hrs/wk, $97,500/yr. Req Bachelor's (or foreign equiv) in Geomatics, Comp Sci or related field and 3 yrs exp as Software Engineer, Systems Engineer, Project Manager, Consultant or Technical Lead and working knowledge of Oracle, Spatial Data Manager and utility company business practices, processes. Mail resume to: WORKFORCE DEVELOPMENT PROGRAMS, PO Box 46547, Denver, CO 80202. Refer to job order no. CO5104447.

GEORGIA STATE UNIVERSITY, Neuroscience and Computational Biomedicine. BRAINS & BEHAVIOR: The Brains & Behavior Program (B&B) at Georgia State University (manager@ cs.gsu.edu) offers graduate fellowships for its new interdisciplinary initiative in neuroscience and behavior. The B&B Program brings together seventy faculty members from eight participating departments, Biology, Chemistry, Computer Science, Computer Information Systems, Mathematics & Statistics, Philosophy, Physics & Astronomy, and Psychology, to

conduct collaborative research and graduate training. Interdisciplinary research groups within B&B include Brains & Computers, Neurons & Networks, Molecules & Brains, Adaptability & Behavior, and Brains & Social Behavior. Each B&B Fellow will matriculate in a member department and be jointly supervised by a neuroscientist and a member from their home department. The Brains & Behavior Program is affiliated with the Center for Behavioral Neuroscience (http://www. cbn-atl.org/research/index.cfm), a National Science Foundation Science and Technology Center. MOLECULAR BASIS OF DISEASE: The Molecular Basis of Disease Area of Focus (MBD) at Georgia State University, Atlanta, GA, (manager@ cs.gsu.edu) is recruiting students for its newly established Ph.D. fellowship program. The MBD Area of Focus is an interdisciplinary program in computational biomedicine that includes over seventy faculty members in the Departments of Biology, Chemistry, Computer Science, Physics and Astronomy, Mathematics and Statistics, and Computer Information Systems. Interdisciplinary research foci within the MBD include Structural Biology, Computational Biology and Bioinformatics, Cancer and Infectious Diseases. Applications should be made directly to the Ph.D. programs of the participating departments. MBD fellows receive an annual stipend of $22,000 plus a full tuition waiver. INFORMATION: For more information and to request application materials, please contact Ms. Adrienne Martin, [email protected], phone: 404-6510610.

SUBMISSION DETAILS: Rates are $290.00 per column inch ($300 minimum). Eight lines per column inch and average five typeset words per line. Send copy at least one month prior to publication date to: Marian Anderson, Classified Advertising, Computer Magazine, 10662 Los Vaqueros Circle, PO Box 3014, Los Alamitos, CA 90720-1314; (714) 821-8380; fax (714) 821-4010.Email: mander [email protected].

In order to conform to the Age Discrimination in Employment Act and to discourage age discrimination, Computer may reject any advertisement containing any of these phrases or similar ones: “…recent college grads…,” “…1-4 years maximum experience…,” “…up to 5 years experience,” or “…10 years maximum experience.” Computer reserves the right to append to any advertisement without specific notice to the advertiser. Experience ranges are suggested minimum requirements, not maximums. Computer assumes that since advertisers have been notified of this policy in advance, they agree that any experience requirements, whether stated as ranges or otherwise, will be construed by the reader as minimum requirements only. Computer encourages employers to offer salaries that are competitive, but occasionally a salary may be offered that is significantly below currently acceptable levels. In such cases the reader may wish to inquire of the employer whether extenuating circumstances apply.

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ADVERTISER / PRODUCT INDEX

FEBRUARY 2005

Advertiser / Product

Page Number

Advertising Sales Representatives

Air Force Research Laboratory

89

Concordia University

88

Cool Chips 2005

25

D.E. Shaw & Company

89

Embedded Systems Conference 2005

18

Fraunhofer Gesellschaft

IEEE Computer Society Membership

Indiana University Bloomington

5

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Cover 3

Intel Developer Forum 2005

Cover 4

IRI 2005

New England (product) Jody Estabrook Phone: +1 978 244 0192 Fax: +1 978 244 0103 Email: [email protected]

New England (recruitment) Robert Zwick Phone: +1 212 419 7765 Fax: +1 212 419 7570 Email: [email protected]

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Hot Chips 2005

International Conferences 2005

Mid Atlantic (product/recruitment) Dawn Becker Phone: +1 732 772 0160 Fax: +1 732 772 0161 Email: [email protected]

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ENTERTAINMENT COMPUTING

Ender’s Game Redux

Long before the invasion of Iraq and the South Asian tsunami, US Marine General Charles Krulak wrote a seminal article in 1999 about the dilemmas facing modern soldiers. In “The Strategic Corporal: Leadership in the ThreeBlock War” (www.au.af.mil/au/awc/ awcgate/usmc/strategic_corporal.htm), Krulak described the need for soldiers who can fight conventional combat in one city neighborhood, transition to peacekeeping operations in another,

Michael Macedonia, Georgia Tech Research Institute

The US military’s new training simulations prepare soldiers for war, peace, and everything in between.

M

y brother, a US Army surgeon in Iraq, sent me an e-mail message not long ago in which he concisely summarized the convergence of entertainment technology and military training to create what Ben Sawyer, a high-tech freelance writer and technology consultant, has dubbed serious games. My brother wrote the following: Our medics are taking care of fresh casualties every day. That is why I think it would be great to have the sim out here because: • We are fairly well restricted to the compound as we are surrounded by the enemy. • Soldiers have not much else to do during their “down time.” • They have real-life experiences they can compare the sims to. • They love computer games.

This situation shows that we live now in a complex world that changes dramatically from day to day. Game technology, now ubiquitous in places like Camp Falluja, Iraq, offers a path to sharing and realizing interactive experiences that mirror reality. To capitalize on this opportunity, the military is developing several simulations that help soldiers train for waging war, keeping the peace, and recovering from the emotional trauma that combat can cause.

ENTERTAINMENT AND TRAINING If necessity is the mother of invention, war is often the midwife. Consider the rapid development of radio in World War I and radar and computing in World War II. The symbiosis between military training and entertainment technology follows a similar pattern. The first flight simulator used by the Navy, the Link Blue Box, sold originally to the Coney Island amusement park while the Navy awaited funding in the 1930s. This legacy lives on in simulators, with the technology going both ways. For example, Disney’s Mission to Mars ride at Walt Disney World’s EPCOT Center provides a technologically complex simulation of space flight that relies on advanced simulation technology from the military aerospace industry. Stanford University’s Timothy Lenoir has documented in detail this longstanding relationship between the military and entertainment (www. stanford.edu/dept/HPST/TimLenoir/ Publications/Lenoir_TheatresOfWar.pdf).

21ST-CENTURY WAR War in the 21st century brings new military training challenges. Published by the IEEE Computer Society

then provide humanitarian relief in a third. Moreover, every decision a soldier makes, from private to general, has become strategically relevant. Thus, Krulak wrote that “The inescapable lesson of Somalia and of other recent operations, whether humanitarian assistance, peacekeeping, or traditional warfighting, is that their outcome may hinge on decisions made by small unit leaders, and by actions taken at the lowest level.” Krulak offers the following prescription for training US soldiers: “The common thread uniting all training activities is an emphasis on the growth of integrity, courage, initiative, decisiveness, mental agility, and personal accountability.”

Crisis simulation One approach the US Army has taken to training for the three-block war involves actually building the blocks in highly instrumented urban war training facilities such as Fort Polk’s Joint Readiness Training Center in Louisiana, with actors who roleplay civilians and terrorists. The experience at JRTC resembles a theme park: Soldiers arrive at some mythical February 2005

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Entertainment Computing

Figure 1. Full Spectrum Leader. This military simulation puts the player in charge of an entire US Army platoon, which must be successfully guided through challenging combat missions.

main street in a distant land, except they’re there not for amusement but serious business. Much like Bill Murray in Ground Hog Day, soldiers at these facilities undergo discovery learning. The seriousness comes across in the After Action Review. An often brutally candid self-examination of what each individual did right and wrong, the AAR is facilitated by experienced observers armed with video and data that document every mistake participants made during the exercise. The army also applies the AAR to simulators such as the Engagement Skills Trainer 2000—a marksmanship system that employs both synthetic 3D graphics and filmed scenarios to teach troops sound judgment in the use of force. The Israeli experience with their version of the EST 2000 provides a good example of how this process works. The Israeli Defense Force’s Lieutenant Colonel Golan, an engineer and enthusiastic computer gamer, believes that units stationed in confrontation zones can use the mobile range to continue 96

to train and maintain their skills. Golan believes that the state-of-the-art simulator can help the IDF do far more than improve its soldiers’ shooting skills during a time when its ethical image is being eroded in its own eyes by one horrific incident after another. Golan noted that every real event is analyzed and the observers’ conclusions drawn up. The officers then decide what lessons can be learned from the incident and work with military personnel experienced in film production to create a video that conveys this information (www.haaretz.com/ hasen/spages/522671.html).

Gaming warfare Unfortunately, combat units rarely get to attend training at instrumented facilities like the JRTC more than once a year. Further, large virtual simulators such as EST 2000 cost significantly more than consumer devices. Thus, during the 1990s, the military began exploring the use of PCs and video game consoles as affordable alternatives to their big simulators. In 1999, the US Army established the

University of Southern California’s Institute for Creative Technologies to foster new training and simulation research that would address Krulak’s Strategic Corporal challenge. The institute exploits entertainment technologies that could enable better methods for developing leadership and decision making. Game technologies became the leading candidate for research because they provide increasingly sophisticated interactive experiences that can be networked via the Internet (www.ict.usc. edu/disp.php?bd=proj_games). This work spurred a flowering of developments in using game technology for training (www.dodgamecommunity. com). James Korris, creative director of ICT, and Pandemic Studios developed perhaps the best-known product of this type, Full Spectrum Warrior, for the Xbox and PC. FSW employs advanced artificial intelligence and user interface techniques that let a player experience the role of a squad leader in urban combat. The game replaces the typically fastpaced first-person shooter design with a more deliberate, 3D real-time strategy game. As the squad leader, you can’t even shoot your weapon—your job is to maneuver your squad through hostile territory without losing members of your team. The version developed by the military so impressed commercial publishers that THQ released it commercially in 2004. The commercial version differs significantly from the military one, however. The Army version received a thorough review for realism by subject-matter experts. Given that it accurately models the challenges of urban combat, it is harder to “win” in this version.

First-person thinker ICT is now at work on the new game shown in Figure 1, Full Spectrum Leader, in which you role-play an infantry platoon leader. This makes your job more complex—you must

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lead 30 soldiers instead of eight—and the missions available are more diverse. FSL will include AI advancements such as an opponent’s ability to recognize players’ actions and respond dynamically. Designed to develop cognitive skills, FSL requires tactical decision making, resource management, and adaptive thinking. Its scenarios focus on asymmetric threats within peacekeeping and peace-enforcement operations. ICT’s Mike van Lent leads the effort to put explainable AI into these simulations. This will give the AI entities— enemies, civilians, and friendly troops— the ability to explain the rationale for their behavior. This, in turn, will enable the games to provide more relevant AARs. Given the cerebral nature of the challenges facing players, FSL may well be the first of its kind: a first-person thinker that takes the fast-paced checkers experience of a first-person shooter and turns it into a strategic speed-chess match.

Simulation therapy Some ICT researchers have proposed using game technology to treat soldiers suffering from post-traumatic stress disorder. Skip Rizzo and Jarrell Pair are extending the research Pair did with Larry Hodges at Georgia Tech by using FSW to treat PTSD. Their version of FSW employs an interface that provides the clinician with the capacity to monitor a patient’s behavior and customize the therapy experience by placing individuals in virtual-environment locations that resemble the setting in which the traumatic events occurred initially. To foster the anxiety modulation needed for therapeutic habituation, the interface also facilitates the gradual introduction and control of trigger stimuli in the environment, in real time. Military psychologists in Iraq support Rizzo and Pair’s research. Soldiers and marines there already play a host of games during their down time.

Psychologists who treat combat stress recommend video games for marines to unwind and boost morale. Erin Simmons, a lieutenant and psychologist with Bravo Surgical Company, noted that tastes in games vary widely: Some soldiers like games with aggressive military content, while others prefer games that provide an experience as different from the war zone as possible. However, the troops find the games relaxing regardless of their preferred genre (http://msnbc.msn.com/id/ 6780587).

Digital linguistics The US military faces a major challenge in providing language and cultural-awareness training to the 150,000 soldiers in Iraq. Thus, another game getting attention within the military is the DARPA-sponsored DARWARS Tactical Language Training System. Lewis Johnson and Stacy Marcelis at USC’s Information Sciences Institute lead the project, which aims to overcome the bottleneck of classroom training. Language training in the military often involves months of classroom instruction and is limited to intelligence specialists. DARWARS, based on a modification of the commercial game Unreal Tournament, provides interactive language learning through speech recognition. Players initially practice on vocabulary items and learn gestures, then apply them in simulated missions. In the simulation, they interact with virtual characters in a variety of scenarios that introduce the player to Arabic culture and language (www.isi.edu/ isd/carte/proj_tactlang).

Environment project is being designed along the lines of games such as Everquest, in which thousands of roleplayers interact in the same 3D-persistent world over the Internet. Forterra president Robert Gehorsam explains that AWE will let a commander tailor his unit’s training to a specific environment and scenario or modify an existing one out of a repository. The relevant training exercises can last anywhere from a couple of days to months, and all of the action will take place online (www.homelanfed.com/index. php?id=20830). The AWE environment now includes a Baghdad database and has been used to develop checkpoint training scenarios for distributed teams in the US National Guard and the active US Army.

Massively multiplayer classroom

n Orson Scott Card’s visionary 1986 science fiction novel, Ender’s Game, the hero, Andrew “Ender” Wiggin, is drafted into Battle School. Although only a child, Ender tackles increasingly difficult simulator missions against an alien race. After he wins the brutally difficult final scenario, Ender realizes that the simulated battle he has just fought was no sim, but the real conflict’s ultimate conclusion. Thus did Card envision the emergence of simulations and games for training and the power of the Internet to influence ideas and change. Ender Wiggin’s bizarre world is no longer fiction. The military is already using the simulation technology of first-person thinkers to help soldiers learn how to fight the three-block war, learn the language of allies and adversaries, heal mental scars, and even save the lives of others. ■

The Army’s Simulation Technology Center is working with Forterra to develop a massively multiplayer online role-playing game for training soldiers throughout the world. Based on the same technology used for the massively multiplayer online game There (www. there.com), the Asymmetric Warfare

Michael Macedonia is a senior scientist at the Georgia Tech Research Institute, Atlanta. Contact him at macedonia@ computer.org.

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INVISIBLE COMPUTING

Creating and Protecting Digital Worlds

Electronics Show (CES), manufacturers displayed PMPs like the one shown in Figure 1 that are a step beyond portable DVD players because they can connect to a PC or set-top box and download content for later viewing. The most powerful of these pocket-sized devices can store up to 320 hours of movies, TV programming, or home video. In the next decade, the availability of vast storage capacity could significantly change the way we use PMPs. Instead of specifying which TV programs, movies, and so on to store, users will store content that has general interest for them and then use

Bill N. Schilit and Roy Want, Intel Research

O

ver the past year, mobile storage capacities have skyrocketed as prices have plummeted. CompactFlash (CF) memory cards that store one gigabyte are now available for about the cost of a 128-Mbyte card one year ago. Tiny rotating media is keeping up: Hitachi is boosting the capacity of its Microdrive, used in the iPod Mini, from 4 to 10 Gbytes. Larger-format 2.5-inch notebook hard drives can now store up to 100 Gbytes. The exponential growth in flash and disk storage is likely to continue for several years as manufacturers digitally encode more types of media and demand increasingly compact formats. For example, Secure Digital flashmemory cards, which now store up to 2 Gbytes, will hold eight times as much data by 2009, while the capacity of 2.5-inch magnetic disks will soar to 500 Gbytes. One use for such large mobile storage capacity is to help deal with information overload. In today’s fast-paced world, people don’t have time to process the overwhelming amount of content available on TV, the radio, the Web, and other media sources. Mobile devices with high memory capacity can personalize and filter media streams in the same way that personal video recorders (PVRs) such as TiVo make it possible to manage hundreds of cable and satellite TV channels.

Users can now personalize large collections of digital data and access it in real time.

These technical achievements highlight the ongoing “invisible computing” revolution that is enabling people, for the first time, to use large amounts of digital data in their everyday activities. Mobile devices are becoming smarter and less reliant on wireless communication, giving users real-time access to an entire digital world. However, as the industry approaches miniature mobile storage devices that can hold 1,000 songs or a 2-Mbyte snapshot from every minute in a day, the danger of losing that world also increases, necessitating simpler and more reliable backup solutions.

PERSONAL DIGITAL VIDEO In 2004, numerous portable media players (PMPs) hit the market including the 20-Gybte Creative Zen Portable Media Center, Samsung’s Yepp YH999 Portable Media Center, the iRiver PMC-140 series (available in 20- and 40-Gbyte versions), and the 80-Gbyte Archos AV480 Pocket Video Recorder. At this year’s International Consumer

video-search software to find exactly what they want. For example, if a user enters “Lord Sainsbury of Turville” in the blinkx search engine (www.blinkx. tv), it will select digitized TV clips and cue them up to the point where they mention the British Minister for Science and Innovation. Simple video-search engines can extract information from the program guide such as a show’s title, description, cast, and credits. They can also work at a deeper level by extracting text-based keywords from closed-caption transcripts or using an audio-mining system that processes speech into a stream of text and then indexes the text with references to the original audio track. Looking further into the future, PMPs could become proactive. For example, after you purchase a tour package from an online travel service, your PMP could extract information from your notebook’s Web browser and present a series of Travel Channel clips corresponding to your itinerary. A future PMP might likewise notice February 2005

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Invisible Computing

be available on wireless Internet radio devices. However, the future of unprotected digital radio remains in doubt. The Recording Industry Association of America has submitted a brief to the US Federal Communications Commission arguing that consumers should be able to record digital broadcasts for later playback but not split a broadcast into individual songs.

CREATING A DIGITAL WORLD

Figure 1. Portable media players can store hundreds of hours of video.

that your digital wallet receipt includes a purchase of Portland cement and then prepare a do-it-yourself masonry video using clips from This Old House and other shows. Massive video storage capacity enables users to personalize a large media collection and access it in real time. With no network connection to backend servers, latency is low and availability is high. With the push of a button, a user can fast-forward to specific entertainment or educational content.

PERSONAL DIGITAL AUDIO Portable music players use solidstate flash memory to store from tens to hundreds of hours of MP3, Windows Media Audio (WMA), Advanced Audio Coding (AAC), and other digital music files. For example, the 1Gbyte version of the palm-size SanDisk Digital Audio Player can store up to 19 hours of audio—roughly equivalent to 280 songs—in 128-Kbps WMA format. Within the next few years, the availability of 32-Gbyte flash memory will allow such devices to store nearly 25 days’ worth of audio content. With so much storage, manufacturers are looking for new ways to flow media into devices. A recent feature 100

appearing in portable music players is an FM tuner with a record mode to capture fresh content. Although FM is not very high fidelity, music capture of digital radio is also at hand: The Delphi MyFi stores five hours of highquality XM Satellite Radio content without a computer download. A new digital radio format is appearing in automobiles and could have a huge impact on recordable music players. With high-definition radio, AM and FM station owners can broadcast digital-CD-quality audio using the existing infrastructure and spectrum in a way that coexists with analog signals. Unlike XM Satellite Radio and Sirius Satellite Radio, which charge a subscription fee, HD radio is free for consumers who have purchased receivers from select manufacturers. Digital radio transmits song title, artist, and other metainformation using standards such as ID3 (www. id3.org). This stream of descriptive data makes it feasible to record particular audio content—for example all the Beatles songs, traffic reports, or BBC news—over the course of a day, offering the same time-shifting capability for audio that PVRs provide for video. Moreover, many of the features of personalized Internet radio will soon

The ability to store large collections of digital video and audio as well as other data and access it anytime, anywhere has emerged as a killer application. As portable device storage capacity increases, so will the diversity of things the devices can store and their utility. Table 1 shows the size of various types of media (www.sims.berkeley.edu/ research/projects/how-much-info-2003/ execsum.htm#stored), which begs the question, how much is enough? Ideally, users would like to combine entertainment content with personal data. Today, advances in mobile solidstate and magnetic storage capacity are enabling portable devices to store not only video and music, but all types of digital data. Following the same downward price trends as CF cards, Universal Serial Bus (USB) flash-memory sticks have become ubiquitous in the past five years. In addition to backing up spreadsheets, presentations, and other business data, these devices, with storage capacities exceeding one gigabyte, serve as a readily available archive of contacts, documents, photos, music files, e-mail, Web bookmarks, and other personal information that mobile professionals can access serendipitously as opportunities arise. If you use a typical 50-Gbyte notebook for mobile computing, you won’t need to delete any content for the machine’s lifetime. In addition, when it’s time to upgrade in three to five years, you’ll be able to transfer all of the old data, which will occupy a fraction of

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the new laptop’s advertised capacity. As personal collections of digital data grow, users are finding it increasingly difficult to manually organize this information on their computer. As one partial response to this problem, Google, Yahoo, and Microsoft are adapting their popular search-engine technologies for all PC content. For example, with Google’s Desktop Search (http://desktop.google.com), users can search the full text of viewed Web pages, e-mail, chats, and document files in various formats, updating information continuously. Declining media prices are providing new opportunities for value-added services based on digital content. For example, manufacturers could preload read/write disks or flash-memory cards with gigabytes of compelling content. In the case of audio and video, this would avoid the long delays and costs associated with downloading files from a network—particularly for mobile devices that only have access to lowbandwidth cellular connections. Developers could use well-known cryptographic techniques to protect copyrighted media. To access this content, a user could simply purchase the appropriate cipher key to decrypt specific files. In addition, to prevent burdening users with undesirable preloaded information, a simple profile describing personal preferences could determine which encrypted data to write over.

PROTECTING YOUR DIGITAL WORLD As mobile devices gain the capacity to store entire digital worlds, the danger of losing all that information in a single disk crash also grows. Ironically, the very technology that makes it possible to create that world can fail catastrophically, causing it to disappear in an instant. Although most users recognize the importance of backing up data, many computing systems remain vulnerable to this kind of calamity. One reason for this is the increasing reliability of disk drives over the past 15 years. A combi-

nation of various safety features, small size, and low head mass has made today’s disk drives less susceptible to damage when dropped or exposed to sudden acceleration. Further, disk-drive failure rates are just low enough to lull users into a false sense of security. This problem is becoming more critical with exponential increases in disk capacity. Not only can you lose more information than ever before, but it takes longer to back up the system, strengthening the psychological barrier to do nothing about it. Solutions abound—the challenge is finding one that suits you and being disciplined enough to use it on a regular basis. Organizations with well-administered computer systems typically make tape backups at night, but for home computing, most people rely on various disk-based technologies. This was once the domain of floppy disks, which writeable CD-ROMs have replaced. However, it takes more than 78 640-Mbyte CD-ROMs to back up a fully loaded 50-Gbyte drive. Reasonably priced writeable 4.7-Gbyte DVDs have been available for a couple of years, but creating these disks remains a long, monotonous process. Not to worry—more optical disk capacity is on the way. The latest double-layer Blu-ray Disc format (www. blu-ray.com) holds 50 Gbytes of data, offering 10 times more storage than a standard DVD—the right ballpark for notebook computers. However, this new technology is expensive, and by the time it drops to an affordable price, notebook disks will have moved up the exponential memory density curve. A popular alternative to the relatively safe optical-disk backup solution is an external (but conventional) disk drive connected either by a USB 2.0 or FireWire cable. It’s highly unlikely that both disks will crash simultaneously, and if so, one would probably survive. In addition, external drives are available for less than $1 per gigabyte that let users initiate a backup by simply pressing a button on the side. By combining ease of use with a

Table 1. How much media is enough? Media

Size

Typewritten page 5 Kbytes Low-resolution photo 100 Kbytes Short novel 1 Mbyte Minute of MP3 audio 1 Mbyte High-resolution photo 2 Mbytes Minute of high-fidelity sound 10 Mbytes Hour of standard-definition video 2 Gbyte Hour of high-definition video 10 Gbytes 10,000 songs in 128-Kbps AAC format 40 Gbytes Library floor of academic journals 100 Gbytes Academic research library 2 Tbytes US Library of Congress print collections 10 Tbytes

pragmatic 300-Gbyte capacity, external disk drives currently offer the most attractive solution to the problem of protecting mobile digital worlds.

torage density for hard disks has been outpacing Moore’s law for some time, with density approximately doubling every year. A palmsize computer can now store large quantities of digital video, audio, and data, making a digital world readily available to mobile users. At the 2005 CES, a bewildering array of personal media devices were on display. Currently, MP3 and photoslideshow players rule, but in a few years, full PMP capability will be available on even the smallest devices. However, with more to lose than ever before, backing up data will be a necessity, not an option. ■

S

Bill N. Schilit is codirector of Intel Research Seattle. Contact him at bill. [email protected]. Roy Want is a principal engineer at Intel Research. Contact him at roy. [email protected]. February 2005

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THE PROFESSION

The Profession and the Big Picture

ilar, if not worse, elevation in temperature is probable by the end of this century. This strongly implies that human society faces a catastrophe. Yet this impending disaster is still not widely realized. As professionals, we have a duty to spread this information. The differences between today’s climate changes and those of past catastrophes derive from their source: Human activity largely drives today’s change, primarily through the extraction of huge amounts of carbon—as gas, oil, and coal—from underground. When used, these minerals subse-

Neville Holmes, University of Tasmania

T

his column has on occasion emphasized that the responsibilities of computing professionals—indeed of any learned profession’s members—go beyond acquiring and applying technical experience and wisdom and beyond acting in their clients’ best interests. The greatest professional responsibility is to act in the best interests of the society to which the profession owes its status. By definition, human society’s greatest interest is its continued existence. It seems the greatest threat to that continuance—climate change—is at last being given credence beyond scientific and environmental circles. The computing profession will play a crucial role in the battle to mitigate the effects of climate change and, if possible, adapt to them. Therefore, we now share a responsibility to inform ourselves of the facts and press for the strategies and measures that we believe will be most effective in combating this threat.

CLIMATE CHANGE The term climate refers to both the pattern of weather over a typical year and variations from typicality over longer periods. Climate varies from place to place, determining the kind of plants and wildlife that can live in a given location and, to a lesser degree, the kind and quality of life people can have there. 104

Computer

The profession must tackle social challenges, the biggest of which is human society’s continued survival. Geological records show quite clearly that climate can change greatly over various time scales. Historically, meteorological records show that the global climate has been gradually warming over the past century, while more recent meteorological records show that extremes of weather are becoming more frequent. Although these meteorological records build a picture of anthropogenic climate change validated by scientific modeling and accepted by practicing climate scientists (www.sciencemag.org/ cgi/content/full/306/5702/1686), some people still deny the facts. As professionals avowing rationality, we should become familiar with these facts and be ready to promptly counter such denials. The most popular denial at the moment is Michael Crichton’s deceptive State of Fear, authoritively rebutted at www. realclimate.org. Geological records show that many of the catastrophic discontinuities that separate major eras coincide with elevated temperatures that result from atmospheric changes. Simple projections of current trends show that a sim-

quently convert to atmospheric carbon dioxide, CO2, presently at double the rate at which the Earth can absorb it. This CO2 buildup has been accepted at an international level as harmful and man-made, although the acceptance lacks any sense of emergency. Indeed, critics typically advance arguments against doing anything about it because a discounted cash flow analysis suggests that countermeasures would be cheaper if postponed. An engineer could easily demolish this absurd kind of argument, which is based on a superficial estimate of the costs involved and an assumption that climate has a simple linear behavior. Like all complex systems, Earth has time constants that could well induce dramatically nonlinear behavior, even unto catastrophe, that no delayed action could avoid.

PREDICTION Human society must react to climate change. Just how it should react depends on reliable predictions of what will happen and how quickly, Continued on page 102

Published by the IEEE Computer Society

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The Profession Continued from page 104

and what effect various countermeasures will have. Such predictions will rely heavily on digital technology. The quality of a digital climate model depends on two factors: the data available and the model itself. Having large amounts of the right kind of data available ensures that the simulation is more reliable and allows refining the model by comparing predictions to outcomes. Digital technology could and should be more widely used to gather, store, and distribute meteorological and geological data. Global climate models are already tremendously complex, and their development makes them steadily more so. Such models are based on 3D spatial grids, so halving the grid spacing to improve accuracy requires eight times as many data points. Refining the model, as discrepancies between prediction and outcome are explained, leads to the need for more data and computation at each grid point. Presently, there are two approaches to climate simulation: distributed, as practiced at www.climateprediction. com, and using supercomputers. Both approaches must be improved continually. This raises the basic problem that prediction cannot simply be a matter of projection. Too many contingencies also need scientific study and modeling: natural contingencies such as methane burps and ocean current changes and human contingencies such as mass migration resulting from the imminent Peruvian parching and the eventual Bangladeshi submersion. As researchers develop a better understanding of these contingencies, they must build the likely effects, singly and in combination, into the overall climate model. From my reading, I suspect that these computations will require special-purpose multiprocessors with, for example, one processor per grid point. The arithmetic might also need improvement to lessen the accumulation of error in such large calculations. Whatever the case, the computing pro102

fession will play a crucial role in developing climate modeling.

MITIGATION The international community already recognizes that the human activity causing global warming must be curbed. The Kyoto Agreement (http://unfccc. int/ essential_background/kyoto_protocol/ items/2830.php) intended just that but seems unlikely to have any nonpolitical effect.

We need to slow the accelerating addition of net CO2 to the atmosphere. The problem seems to be that key political agents either do not know or do not accept the relevant facts. For example, at the recent two-week UN conference on climate change in Buenos Aires, the US representatives reportedly said that their government wants to concentrate on long-term programs to develop cleaner-burning energy technologies (www.state.gov/g/ oes/rls/fs/2004/38641.htm). This statement implies that they do not understand that dirty burning has been lessening global warming, while the burning of fossil fuels adds CO2 to the atmosphere and—perhaps just as seriously in the long run—any burning removes oxygen from it. There is no doubt that we need to slow the accelerating addition of net CO2 to the atmosphere, even though it is not the only cause of climate change. Indeed it’s possible that soon we will need to actually reduce the CO2 content to avoid catastrophe. Better modeling would give us a better idea of what’s needed and provide a more persuasive argument to make to the politicians. Because the situation calls for political action, informing the public of the relevant facts and projections might seem a practical activity, one in which computing professionals could use the Web and media as useful conduits. However, this assumes that an effec-

tive percentage of the public can understand the relevant scientific evidence and reasoning. This assumption might well be wrong. For example, The Nation’s Report Card: Mathematics 2000 noted that more than one-third of US high school seniors lack basic proficiency in mathematics (http://nces.ed.gov/ nationsreportcard/pdf/main2000/2001 517.pdf). Worse, fewer than one-sixth have better than a basic proficiency. Clearly, the computing profession should be pushing for the use of computers in schools simply to inculcate such basic skills, not just to ensure that younger people can understand what the climate has in store for them. If we accept the need for practical and intense mitigation, a boost to education is crucial because of the underlying need for more scientists to analyze and model the climate and for more engineers to design and implement the machinery for mitigation. Further, given digital technology’s potential to help educators, scientists, and engineers be more effective, more computing professionals will be needed. And their education must focus on the problems they will face.

ADAPTATION Engineers in general, and computing professionals in particular, understand professionally the likely short-term and long-term behavior of complex systems. The Earth’s climate is changing now, will change dramatically within a few human generations, and could change catastrophically in the longer term. These changes will drastically affect human society. If this is not soon accepted globally and officially, the world’s scientists and engineers must take a large part of the blame. The greatest danger is that human society will not adapt to the inevitable changes. Both mitigation and adaptation must be technologically based, just as the climate change itself is. In the worst case, the human effects of widespread starvation and thirst brought on by glacier disappearance alone

Computer

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could cause social disruption widespread enough to block the development and use of mitigation technology. Governments will need to use technology of many kinds, necessarily supported by digital technology, in critically threatened areas in the immediate future simply to keep people there supplied with food and water. In the medium term, agriculture as we know it might not survive if we cannot stop the spread of deserts. Should this occur, scientists would need to develop ways to industrially manufacture food. The flooding of low-lying coastal areas will require either constructing enormous levee banks or relocating many of the world’s largest cities and densest rural populations. Increasing heat will mean that a large proportion of the world’s population will depend on air conditioning for its very survival—even now, thousands die of extreme summer heat each year. Extremes of weather will require constructing buildings and the infrastructure more sturdily or even completely redesigning them. In the long run, if mitigation is unsuccessful, the human race will be forced to live in a completely artificial

environment, isolated from Earth’s climate. Achieving this will present a huge technological challenge. On the bright side, if we succeed, we should be able to colonize the Moon and Mars as well.

MOTIVATION Some readers may view this essay as mere scaremongering. I intend it to scare, but only because my reading has convinced me that the human race faces truly frightening prospects and that we might indeed already be doomed, at least as a civilization. I ask only that those of you who remain unconvinced of the reality of these threats at least read some of the resources I have found—all directly or indirectly available through our wonderful Web and discoverable using its search engines. George Monbiot’s short essay, “Goodbye, Kind World” (www.monbiot.com/archives/2004/08/ 10/goodbye-kind-world-/), shows that I am not alone in my apprehensions. Mark Lynas’s book, High Tide (Flamingo, 2004; www.marklynas.org), is a persuasive and well-documented eyewitness account of some climate change effects already being felt. More details can be found at govern-

ment Web sites such as the Intergovernmental Panel on Climate Change (www.ipcc.ch), academic Web sites such as that for the American Institute of Physics (www.aip.org/history/climate/ summary.htm), and activists’ Web sites such as www.worldwatch.org and www.climateark.org. echnology has almost entirely shaped the outward aspects of our civilization, and civilization’s use of technology will certainly determine its own fate. Given that digital technology has become the main enabler of other technologies, this issue has undeniable relevance to the computing profession. In this case, we face the real danger that inaction by our profession and others might force us to share the fate of the apocryphal frog who, oblivious to his imminent demise, boiled to death in a gradually warming saucepan. ■

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Neville Holmes is an honorary research associate at the University of Tasmania’s School of Computing. Contact him at [email protected]. Details of citations in this essay and links to further material are at www. comp.utas.edu.au/users/nholmes/prfsn.

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