Document Reference: TN201009003 - Rev: 4.14 - Last Update: 14-11-2020 03:42 GMT - Downloaded: 02-Oct-2023 01:09 GMT
A OR gate is a logic gate with two or more inputs and one output. One or more input states must be high to produce a high output.
OR Gate Symbols
The inputs (A, B
) of an OR gate are on the left, and the output (X
) is on the right of the logic OR gate symbol.
Distinctive Shape | Rectangular Shape | DIN Shape (Historic) |
---|---|---|
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OR Gate Truth Tables
Truth Table for OR Gate with 2 Inputs
A | B | X |
---|---|---|
0 | 0 | 0 |
0 | 1 | 1 |
1 | 0 | 1 |
1 | 1 | 1 |
Truth Table for OR Gate with 3 Inputs
A | B | C | X |
---|---|---|---|
0 | 0 | 0 | 0 |
0 | 0 | 1 | 1 |
0 | 1 | 0 | 1 |
0 | 1 | 1 | 1 |
1 | 0 | 0 | 1 |
1 | 0 | 1 | 1 |
1 | 1 | 0 | 1 |
1 | 1 | 1 | 1 |
OR Gate Test-It
To test the gate, click the switch symbols in the image below.
OR Gate Logical Expressions
Word Equation
X = A OR B
Boolean Algebra
In boolean algebra the plus sign (+
) stands for the OR operation, e.g.:
X = A + B
Alternative notation: X = A ∨ B
A | B | X = A + B |
---|---|---|
0 | 0 | X = 0 + 0 = 0 |
0 | 1 | X = 0 + 1 = 1 |
1 | 0 | X = 1 + 0 = 1 |
1 | 1 | X = 1 + 1 = 1 |
A | B | C | X = A + B + C |
---|---|---|---|
0 | 0 | 0 | X = 0 + 0 + 0 = 0 |
0 | 0 | 1 | X = 0 + 0 + 1 = 1 |
0 | 1 | 0 | X = 0 + 1 + 0 = 1 |
0 | 1 | 1 | X = 0 + 1 + 1 = 1 |
1 | 0 | 0 | X = 1 + 0 + 0 = 1 |
1 | 0 | 1 | X = 1 + 0 + 1 = 1 |
1 | 1 | 0 | X = 1 + 1 + 0 = 1 |
1 | 1 | 1 | X = 1 + 1 + 1 = 1 |