Programmable Array Logic

Programmable Array Logic (PAL) is a family of <a href="/facts/Programmable_logic_device/7dIVypm9">programmable logic device</a> semiconductors used to implement <a href="/facts/Logic/8JnpJLtt">logic</a> functions in digital <a href="/facts/Electrical_network/zt94kTW0">circuits</a> that was introduced by <a href="/facts/Monolithic_Memories/1wJgs6A2">Monolithic Memories</a>, Inc. (MMI) in March 1978. MMI obtained a registered trademark on the term PAL for use in "Programmable Semiconductor Logic Circuits". The trademark is currently held by <a href="/facts/Lattice_Semiconductor/aPJY9jNu">Lattice Semiconductor</a>.
PAL devices consisted of a small <a href="/facts/Programmable_read-only_memory/amoyxIFx">PROM</a> (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:

<ul><li>"<a href="/facts/One-time_programmable/amoyxIFx">One-time programmable</a>" (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.)</li>
<li>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 <a href="/facts/EPROM/kXcEca36">EPROM</a>.</li>
<li>Later versions (PALCExxx e.g.: PALCE22V10) were flash erasable devices.</li></ul>
In most applications, electrically erasable <a href="/facts/Generic_array_logic/JF3rWy3A">GALs</a> are now deployed as <a href="/facts/Pin_compatibility/uB7b5yQk">pin-compatible</a> direct replacements for one-time programmable PALs.

Programmable Array Logic open-in-new

Programmable Array Logic