NOR Gate Simulation in Proteus Software

NOR Gate Introduction:

The NOR gate is a digital logic gate that implements logical NOR - it behaves according to the truth table to the right. A HIGH output (1) results if both the inputs to the gate are LOW (0); if one or both input is HIGH (1), a LOW output (0) results.

NOR is the result of the negation of the OR operator. It can also be seen as an AND gate with all the inputs inverted. NOR is a functionally complete operation—NOR gates can be combined to generate any other logical function. By contrast, the OR operator is monotonic as it can only change LOW to HIGH but not vice versa.


In most, but not all, circuit implementations, the negation comes for free—including CMOS and TTL. In such logic families, OR is the more complicated operation; it may use a NOR followed by a NOT. A significant exception is some forms of the domino logic family.

NOR Gate Simulation in Proteus Software




Symbols of NOR Gate

There are three symbols for NOR gates: the American (ANSI or 'military') symbol and the IEC ('European' or 'rectangular') symbol, as well as the deprecated DIN symbol. For more information see Logic Gate Symbols. The ANSI symbol for the NOR gate is a standard OR gate with an inversion bubble connected.

Alternatives for NOR Gate

If no specific NOR gates are available, one can be made from NAND gates, because NAND and NOR gates are considered the "universal gates", meaning that they can be used to make all the others.

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Related Links: 

AND Gate
OR Gate
NOT Gate
NAND Gate

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