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Sahithyan's S2
Sahithyan's S2 — Computer Organization and Digital Design

PLA and PAL

A Programmable Logic Device is an electronic component used to build digital circuits that can be programmed by the user to perform a variety of logical operations.

Programmable Logic Array

A PLD with programmable AND gate array followed by programmable OR gate array. High flexibility. Slower. Expensive.

Programmable Logic Array

Image from Electronics Tutorial website.

Input Buffer

Takes in 1 input () and produces 2 outputs ( and ).

Steps

  • Write down the truth table
  • Reduce minimal SOP form for outputs
  • Find total number of input buffers (which is equal to number of inputs)
  • Find total number of programmable AND gates (= no of minterms)
  • Find total number of programmable OR gates (= no of functions)

Programmable Array Logic

Most commonly used type of PLD. Has programmable AND gate array and fixed OR gate array. Moderate flexibility. Cheaper. Faster.

Programmable Array Logic

Image from Electronics Tutorial website.