Conventional Computers and Loosely Distributed Networks

The computer's single processor accesses a single memory, and inputs and outputs information to and from the external world. The processor's arithmetic logic unit plus controller and high-speed registers make up the single CPU. Often there are several input devices and several output devices and a hierarchy of successively slower and larger memories. However, computing is done by the single processor using data and program stored in its main memory. This chapter reviews this kind of traditional system. It also discusses several relatively straightforward first steps toward building computer systems that have more than one processor—computers with two or three processors sharing the main memory—and distributed networks of computers. It also describes the parallel aspects of serial computers.