NOR Gate

A NOR gate (sometimes referred to by its extended name, Negated OR gate) is a digital logic gate with two or more inputs and one output with behavior that is the opposite of an OR gate. The output of a NOR gate is true all of its inputs are false. If one or more of a NOR gate's inputs are true, then the output of the NOR gate is false.

The truth table for a NOR gate with two inputs appears to the right.

Symbols

Each of the symbols below can be used to represent a NOR 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 a NOR gate behaves.

Further Reading

To learn more, check out the following external resources:

• NOR gate on Wikipedia

• Multiple-input gates on All About Circuits

• Derived Logical Functions and Gates at Play-Hookey

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