Field Programmable Logic Arrays

1 Inputs 00 e1 • II O1 0 1 0 00 01 1 11 PROM 16 worth z 4 bits (empty) • ••• ii 110.0 OR way EE 41 October 1988 FIELD PROGRAMMABLE LOGIC ARRAYS The Programmable Logic Array, PAL, introduced in the early 1980s, has been slow in being accepted by designers, in spite of a promising start. The Field Programmable Logic Array, FPLA, a more flexible device that is a cross between PAL and PROM (Programm- able Read Only Memory), has established itself rather more quickly. A programmable logic device is a halfway house between standard logic ICs and custom-design ICs. It thus com- bines the financial advantages of large- scale production of the former and the flexibility and compactness of the latter. Programmable logic devices can be classified under four headings: (1) Pro- grammable Read Only Memory - PROM; (2) Programmable Array Logic - PAL; (3) Field Programmable Logic Array - FPLA; and (4) Field Pro- grammable Logic Sequencer - FPLS. The PROM is probably the best known ...