Silicon, Circuits, and the Digital Revolution

Introduction to Digital Logic: NAND Gate

The truth table for the NAND gate is commonly written in one of the two forms below, where the true state T is represented by 1 and the false state F is represented by 0. (See previous class for physical realization via transistor switches.

A: B: C: A: B: C:
(in) (in) (out)   (in) (in) (out)
F F T   0 0 1
F T T   0 1 1
T F T   1 0 1
T T F   1 1 0

The NAND is one of the binary operations most heavily used in digital logic, an operation involving two input states, resulting in one of two possible output states. These electronic circuits are known as gates because they control the flow of bits (information) through the overall circuit; e.g., the computer.

Note that the truth table is independent of fabrication details; i.e. whether it is a CMOS gate or from a different logic "family" does not change the logic of the operation -- the actual gate is constructed to create the desired truth table.

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Last updated May 4, 2000.
© George Watson, Univ. of Delaware, 2000.