growth in computing performance. (Chapter 4 explores implications for software and programming in more detail.)

This chapter first considers the general question of why faster computers are important. It then examines four broad fields—science, defense and national security, consumer applications, and enterprise productivity—that have depended on and will continue to depend on sustained growth in computing performance. The fields discussed by no means constitute an exhaustive list,1 but they are meant to illustrate how computing performance and its historic exponential growth have had vast effects on broad sectors of society and what the results of a slowdown in that growth would be.


Computers can do only four things: they can move data from one place to another, they can create new data from old data via various arithmetic and logical operations, they can store data in and retrieve them from memories, and they can decide what to do next. Students studying computers or programming for the first time are often struck by the surprising intuition that, notwithstanding compelling appearance to the contrary, computers are extremely primitive machines, capable of performing only the most mind-numbingly banal tasks. The trick is that computers can perform those simple tasks extremely fast—in periods measured in billionths of a second—and they perform these tasks reliably and repeatably. Like a drop of water in the Grand Canyon, each operation may be simple and may in itself not accomplish much, but a lot of them (billions per second, in the case of computers) can get a lot done.

Over the last 60 years of computing history, computer buyers and users have essentially “voted with their wallets” by consistently paying more for faster computers, and computer makers have responded by pric-


1Health care is another field in which IT has substantial effects—in, for example, patient care, research and innovation, and administration. A recent National Research Council (NRC) report, although it does not focus specifically on computing performance, provides numerous examples of ways in which computation technology and IT are critical underpinnings of virtually every aspect of health care (NRC, 2009, Computational Technology for Effective Health Care: Immediate Steps and Strategic Directions, Washington, D.C.: The National Academies Press, available online at Yet another critically important field that increasingly benefits from computation power is infrastructure. “Smart” infrastructure applications in urban planning, high-performance buildings, energy, traffic, and so on are of increasing importance. That is also the underlying theme of two of the articles in the February 2009 issue of Communications of the ACM (Tom Leighton, 2009, Improving performance on the Internet, Communications of the ACM 52(2): 44-51; and T.V. Raman, 2009, Toward 2W: Beyond Web 2.0, Communications of the ACM 52(2): 52-59).

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