A NOR gate performs an inclusive OR operation followed by an inversion. Its output is driven high if and only if every input is low; if any input is pulled high, the output goes low. Along with the NAND gate, it is a universal logic gate, meaning any digital circuit can be constructed entirely from NOR gates.
Heard on the job
Tie the two inputs of that NOR gate together and you can use it as a simple inverter.
Related terms
OR gate
A basic digital logic gate that outputs high if any of its inputs are high.
NOT gate
A digital logic gate that outputs the inverse of its input state.
NAND gate
A fundamental digital logic gate that outputs low only when all its inputs are high.
Universal logic gate
A logic gate type that can be combined to reproduce any other boolean logic function.