Editing Programmable Array Logic (section)

{{Short description|Field-programmable semiconductor devices}}
{{distinguish|Programmable logic array}}

[[File:MMI PAL 16R6.jpg|thumb|MMI 16R6 in 20-pin [[Dual in-line package|DIP]]]]
[[File:AMD PAL 22V10.jpg|thumb|AMD 22V10 in 24-pin DIP]]
'''Programmable Array Logic''' ('''PAL''') is a family of [[programmable logic device]] semiconductors used to implement [[logic]] functions in digital [[electrical network|circuits]] that was introduced by [[Monolithic Memories]], Inc. (MMI) in March 1978.<ref name="MMI PAL Ad">{{Cite journal |title=Monolithic Memories announces: a revolution in logic design |journal=Electronic Design |volume=26 |issue=6 |pages=148B, 148C |publisher=Hayden Publishing |location=Rochelle, NJ |date=March 18, 1978}} Introductory advertisement on PAL (Programmable Array Logic).</ref> MMI obtained a registered trademark on the term PAL for use in "Programmable Semiconductor Logic Circuits". The trademark is currently held by [[Lattice Semiconductor]].<ref name="PAL trademark">Monolithic Memories, Inc (MMI) filed for a work mark on the term "PAL" for use in "Programmable Semiconductor Logic Circuits" on April 13, 1978. A registered trademark was granted on April 29, 1980, registration number 1134025. MMI's first use of the term PAL in commerce was on February 21, 1978. The trademark is currently held by Lattice Semiconductor Corporation of Hillsboro, Oregon. Source: United States Patent and Trademark Office online database.</ref>

PAL devices consisted of a small [[Programmable read-only memory|PROM]] (programmable read-only memory) core and additional output logic used to implement particular desired logic functions with few components.

Using specialized machines, PAL devices were "field-programmable". PALs were available in several variants:

* "[[One-time programmable]]" (OTP) devices could not be updated and reused after initial programming. (MMI also offered a similar family called HAL, or "hard array logic", which were like PAL devices except that they were mask-programmed at the factory.)
* UV erasable versions (e.g.: PALCxxxxx e.g.: PALC22V10) had a quartz window over the chip die and could be erased for re-use with an ultraviolet light source just like an [[EPROM]].
* Later versions (PALCExxx e.g.: PALCE22V10) were flash erasable devices.

In most applications, electrically erasable [[generic array logic|GAL]]s are now deployed as [[Pin compatibility|pin-compatible]] direct replacements for one-time programmable PALs.