The Transistor Transistor Logic (TTL) NOR gate is a combination of OR gate followed by a NOT gate. The output is LOW, when any of its inputs is HIGH, OR gate and NOT gate logic are combined to produce the NOR operation.
The NOR gate has two or more inputs and a single output. It produces a HIGH means 5VDc power supply output when all of its inputs are Low.
The input variables are A,B and the output variable is Y, then the logic expression for NOR gate is Y = Above the table.Application:can be used as universal gate.
IC 7402 is a 14 pin dual-in-line package.