used or are without PCs will use the smaller, simpler devices and avoid the PC’s complexity; and existing PC users will adopt them for simplicity, mobility, and functionality. We clearly see these small personal devices with annual volumes of several hundred million units becoming the single universal device evolving from the phone, PDA, camera, personal audio/video device, Web browser, GPS and map, wallet, personal identification, and surrogate memory.

With every TV becoming a computer display, a coupled SFF becomes the personal computer for the remaining applications requiring large screens. Cable companies will also provide access via this channel as TV is delivered digitally.

Ubiquitous Wireless: WiFi, Cellular Services, and Wireless Sensor Nets. Unwiring the connection around the computer and peripherals, televisions, and other devices by high-speed radio links is useful but the function is “unwiring,” and not platform creation. Near-Field Communication (NFC) using RF or magnetic coupling offers a new interface that can be used to communicate a person’s identity that could form a new class for wallets and identity. However, most likely the communication channel and biometric technology taken together just increase the functionality of small devices.

Wireless Sensor Nets: New Platform, Network, and Applications. Combining the platform, wireless network, and interface into one to integrate with other systems by sensing and effecting is clearly a new class that has been forming since 2002 with a number of new companies that are offering unwiring, and hence reduced cost for existing applications, such as process, building, home automation, and control. Standards surrounding the 802.15.4 link that competes in the existing unlicensed RF bands with 802.11xyz, Bluetooth, and phone transmission are being established.

New applications will be needed for wireless sensor nets to become a true class versus just unwiring the world. If, for example, these chips become part of everything that needs to communicate in the whole IT hierarchy, a class will be established. They carry out three functions when part of a fixed environment or a moving object: sense/effect; recording of the state of a person or object (things such as scales, appliances, switches, thermometers, and thermostats) including its location and physical characteristics; and communication to the WiFi or other special infrastructure network for reporting. RFID is part of this potentially very large class of trillions. Just as billions of clients needed millions of servers, a trillion dust-sized wireless sensing devices will be coupled to a billion other computers.

Bell’s Law explains the history of the computing industry based on the properties of computer classes and their determinants. This article has posited a general theory for the creation, evolution, and death of various priced-based computer classes that have come about through circuit and semiconductor technology evolution from 1951. The exponential transistor density increases forecast by Moore’s Law [ 6] being the principle basis for the rise, dominance, and death of computer classes after the 1971 microprocessor introduction. Classes evolve along three paths: constant price and increasing performance of an established class; supercomputers—a race to build the largest computer of the day; and novel, lower-priced “minimal computers.” A class can be subsumed by a more rapidly evolving, powerful, less-expensive class given an interface and functionality. In 2010, the powerful microprocessor will be the basis for nearly all classes from personal computers and servers costing a few thousand dollars to scalable servers costing a few hundred million dollars. Coming rapidly are billions of cell phones for personal computing and the tens of billions of wireless sensor networks to unwire and interconnect everything. As I stated at the outset, in the 1950s a person could walk inside a computer and by 2010 a computer cluster with millions of processors will have expanded to the size of a building. Perhaps more significantly, computers are beginning to “walk” inside of us. ^c

REFERENCES

1. Bell, C.G. The mini and micro industries. Computer 17, 10 (Oct. 1984), 14– 30.

2. Bell, C.G. Multis: A new class of multiprocessor computers. Science 228 (Apr. 26, 1985) 462–467.

3. Bell, G. and Strecker, W. Computer structures: What have we learned from the PDP- 11. IEEE Computer Conference Proceedings (Florida, Nov. 1975).

4. Christensen, C.M. The Innovator’s Dilemma. Harvard Business School Press, 1997.

5. Gray, J. and Shenoy, P. Rules of thumb in data engineering. In Proceedings of ICDE200 (San Diego, Mar. 1– 4, 2000). IEEE press.

6. Moore, G.E. Cramming more components onto integrated circuits. Electronics 8, 39 (Apr. 19, 1965); revised 1975.

7. Nelson, D.L. and Bell, C.G. The evolution of workstations. IEEE Circuits and Devices Magazine (July 1986), 12– 15.

GORDON BELL ( [e-mail]) is a principal researcher in Microsoft Research Silicon Valley, working in the San Francisco Laboratory.

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