Document Reference: TN201009005 - Rev: 4.14 - Last Update: 14-11-2020 03:50 GMT - Downloaded: 02-Oct-2023 00:38 GMT
A NOR gate is a logic gate with two or more inputs and one output. All inputs states must be low to produce a high output.
NOR Gate Symbols
The inputs (A, B
) of an NOR gate are on the left, and the output (X
) is on the right of the logic NOR gate symbol.
Distinctive Shape | Rectangular Shape | DIN Shape (Historic) |
---|---|---|
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NOR Gate Truth Tables
Truth Table for NOR Gate with 2 Inputs
A | B | X |
---|---|---|
0 | 0 | 1 |
0 | 1 | 0 |
1 | 0 | 0 |
1 | 1 | 0 |
Truth Table for NOR Gate with 3 Inputs
A | B | C | X |
---|---|---|---|
0 | 0 | 0 | 1 |
0 | 0 | 1 | 0 |
0 | 1 | 0 | 0 |
0 | 1 | 1 | 0 |
1 | 0 | 0 | 0 |
1 | 0 | 1 | 0 |
1 | 1 | 0 | 0 |
1 | 1 | 1 | 0 |
NOR Gate Test-It
To test the gate, click the switch symbols in the image below.
NOR Gate Logical Expressions
Word Equation
X = NOT (A OR B)
Boolean Algebra
In boolean algebra the plus sign (+
) combined with the overbar sign (
) stands for the NOR operation, e.g.:
X = A + B
Alternative notations: X = A ∨ B
or X = A ∨ B
or X = A − B
A | B | X = A + B |
---|---|---|
0 | 0 | X = 0 + 0 = 0 = 1 |
0 | 1 | X = 0 + 1 = 1 = 0 |
1 | 0 | X = 1 + 0 = 1 = 0 |
1 | 1 | X = 1 + 1 = 1 = 0 |
A | B | C | X = A + B + C |
---|---|---|---|
0 | 0 | 0 | X = 0 + 0 + 0 = 0 = 1 |
0 | 0 | 1 | X = 0 + 0 + 1 = 1 = 0 |
0 | 1 | 0 | X = 0 + 1 + 0 = 1 = 0 |
0 | 1 | 1 | X = 0 + 1 + 1 = 1 = 0 |
1 | 0 | 0 | X = 1 + 0 + 0 = 1 = 0 |
1 | 0 | 1 | X = 1 + 0 + 1 = 1 = 0 |
1 | 1 | 0 | X = 1 + 1 + 0 = 1 = 0 |
1 | 1 | 1 | X = 1 + 1 + 1 = 1 = 0 |