Bell’s Law explains the history of the computing industry based on the properties of computer classes and their determinants. The paper posits 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 (1965,1975) 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 nets to unwire and interconnect everything. In 1951, a man could walk inside a computer and by 2010 a computer cluster with millions of processors has expanded to building size. More importantly, computers are beginning to “walk” inside of us.