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Software → Digital Logic

Logic Gate

A basic digital circuit that performs a Boolean operation such as AND, OR, or NOT.

Logic gate diagram

Motivation

Logic gates solve the problem of turning binary signals into computation. They are the bridge between electrical circuits and Boolean logic.

Where it fits

Logic gates belong to digital logic. They are built from transistors and used to construct adders, registers, memory, and CPUs.

Subconcepts

AND Gate, OR Gate, and NOT Gate

The AND Gate, OR Gate, and NOT Gate implement the basic logical operations.

NAND Gate and NOR Gate

The NAND Gate and NOR Gate are universal gates: either one can be used to build all other Boolean operations.

XOR Gate

The XOR Gate is useful when detecting difference between bits, especially in adders.

Common mistakes

  • Thinking gates are only abstract truth tables. They are also physical circuits.
  • Forgetting that NAND/NOR are enough to construct complete digital systems.