The advent of low-cost microcomputer chip sets is having a dramatic impact on the direction of digital design. Except for very cost-sensitive products, most new designs are constructed utilizing programmable logic to replace more conventional random logic designs. The premise of this new logic form is based on the cost savings exhibited by solutions consisting of a small number of different LSI parts over those with many SSI/MSI parts performing the same functions. Low LSI parts costs are achieved by producing functions (e.g., RAM, ROM, processor, and I/O parts) with general utility so that each chip can be manufactured in very high volume. Logic functions are realized by specifying a set of step-by-step instructions which are executed sequentially by the processor.