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
In most, but not all, circuit implementations, the negation comes for
free—including
The original
CONTENTS * 1 Symbols * 2 Hardware description and pinout * 2.1 Availability * 3 Implementations * 3.1 Alternatives * 4 See also * 5 References * 6 External links SYMBOLS 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
_ MIL/ANSI Symbol_
_IEC Symbol_
_
NOR
HARDWARE DESCRIPTION AND PINOUT NOR Gates are basic logic gates, and as such they are recognised in
TTL and
Pinout Diagram of a 4001 Quad NOR DIP -format IC 1 Input A1 2 Input B1 3 Output Q1 4 Output Q2 5 Input B2 6 Input A2 7 Vss 8 Input A3 9 Input B3 10 Output Q3 11 Output Q4 12 Input B4 13 Input A4 14 Vdd AVAILABILITY These devices are available from most semiconductor manufacturers
such as
In the popular
*
* 4001: Quad 2-input NOR gate * 4025: Triple 3-input NOR gate * 4002: Dual 4-input NOR gate * 4078: Single 8-input NOR gate * TTL * 7402: Quad 2-input NOR gate
* 7427: Triple 3-input NOR gate
* 7425: Dual 4-input N
In the older RTL and ECL families, NOR gates were efficient and most commonly used. IMPLEMENTATIONS PMOS N
The diagrams above show the construction of a 2-input N
The diagram below shows a 2-input N
ALTERNATIVES 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 other gates. NAND CONSTRUCTION SEE ALSO *
REFERENCES * ^ Mano, M. Morris and Charles R. Kime. _Logic and Computer Design Fundamentals, Third Edition._ Prentice Hall, 2004. p. |