NOR gate symbol
Also called NOR, Not OR
The output is 1 only when all inputs are 0: an OR gate followed by NOT.
ANSI / IEEE
IEC 60617What the NOR gate symbol means
The output is 1 only when all inputs are 0: an OR gate followed by NOT.
ANSI and IEC symbols
Where you see it
Digital electronics, PLC function block diagrams, interlock and safety logic, and cause and effect logic.
Related symbols
Frequently asked questions
What does the NOR gate symbol look like?
On ANSI drawings: An OR body with a circle at the output. In IEC 60617: A rectangle marked ≥1, with a small circle at the output for the inverted output.
Is the NOR gate symbol the same in IEC and ANSI?
No. A rectangle marked ≥1, with a small circle at the output for the inverted output.
Where is a NOR gate used?
Digital electronics, PLC function block diagrams, interlock and safety logic, and cause and effect logic.
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