OR Gate

Truth table for an OR gate

Input A	Input B	Output
false	false	false
false	true	true
true	false	true
true	true	true

An OR gate is a digital logic gate with two or more inputs and one output that performs logical disjunction. The output of an OR gate is true when one or more of its inputs are true. If all of an OR gate's inputs are false, then the output of the OR gate is false.

The truth table for an OR gate with two inputs appears to the right.

Symbols

Each of the symbols below can be used to represent an OR gate. There are multiple international standards defined, and one may preferred over the other in your region of the world.

ASNI / IEEE	IEC

Live Example

Try the following interactive example to see for yourself how an OR gate behaves.

Further Reading

To learn more, check out the following external resources:

• OR gate on Wikipedia

• Multiple-input gates on All About Circuits

• Basic Logical Functions and Gates at Play-Hookey

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