Home > programmable logic devices > programmable logic array

Programmable Logic Array

A programmable logic array (PLA) has a programmable AND array at the inputs and programmable OR array at the outputs. The PLA has a programmable AND array instead of hard-wired AND array. The number of AND gates in the programmable AND array are usually much less and the number of inputs of each of the OR gates equal to the number of AND gates. The OR gate generates an arbitrary Boolean function of minterms equal to the number of AND gates. Figure below shows the PLA architecture with four input lines, a programmable array of eight AND gates at the input and a programmable array of two OR gates at the output.



PLA architecture more efficient than a PROM.

PLA architecture has two sets of programmable fuses due to which PLA devices are difficult to manufacture, program and test.