ABSTRACT
This chapter examines integrated circuits that are not restricted to single-function operations and that can be used in the design of a general digital system. In a programmable logic system, a standard hardware structure is electronically recon-figurable so that the different logic operations can be performed, without having to change the circuit physically. The multiplexer is a multi-input, single-output circuit whose prime function is to convert parallel data to serial data. The multiplexer can also be used as a universal combinational logic function. In a multilayer multiplexer system, logic functions are generated by multiplexers, which are then input to a second and subsequent layers of multiplexers. A memory can act as a logic function simply by storing a truth table, and as any truth table can be loaded into store, the device is both programmable and universal. The microprocessor itself can now be regarded as a component in a digital system.
