Partitioning, predictability, P-terms and pinlocking-understanding the new CPLDs

Abstract

Bipolar Programmable Logic Arrays were first commercially marketed in the 1970s. They were found to be flexible and had adequate pins, but were also slow and expensive. By eliminating one programmable array, Programmable Array Logic was derived. Both architectures evolved along with customer expectations regarding architectural capabilities. A key architectural direction was that of uniform capability macrocells. This is best demonstrated by the popular 16V8 and 22V10 devices. Both contain flip flops with similar capabilities (setshesets, clock options, feedback, etc.), but the 16V8 has identical product term distribution per macrocell where the 22V10 has a distribution ranging from eight product terms to 16 product terms.