How To Draw The Dual Of A Nor Gate

This article is about NOR in the sense of an electronic logic gate (e.g. CMOS 4001). For NOR in the purely logical sense, run across Logical NOR. For other uses of NOR or Nor, see Nor (disambiguation).

Input		Output
A	B	A NOR B
0	0	i
0	1	0
1	0	0
1	i	0

The NOR gate is a digital logic gate that implements logical NOR - it behaves co-ordinate to the truth table to the correct. A Loftier output (i) results if both the inputs to the gate are Depression (0); if ane or both input is HIGH (one), a LOW output (0) results. NOR is the issue of the negation of the OR operator. It can also in some senses be seen as the inverse of an AND gate. NOR is a functionally complete functioning—NOR gates tin be combined to generate any other logical function. Information technology shares this property with the NAND gate. By contrast, the OR operator is monotonic as it tin can just 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; information technology may use a NOR followed by a NOT. A significant exception is some forms of the domino logic family.

The original Apollo Guidance Computer used 4,100 integrated circuits (IC), each 1 containing only two 3-input NOR gates.^[i]

Symbols [edit]

There are 3 symbols for NOR gates: the American (ANSI or 'armed forces') symbol and the IEC ('European' or 'rectangular') symbol, besides as the deprecated DIN symbol. For more information encounter Logic Gate Symbols. The ANSI symbol for the NOR gate is a standard OR gate with an inversion bubble connected. The chimera indicates that the function of the or gate has been inverted.

Hardware description and pinout [edit]

NOR Gates are bones logic gates, and as such they are recognised in TTL and CMOS ICs. The standard, 4000 serial, CMOS IC is the 4001, which includes 4 independent, ii-input, NOR gates. The pinout diagram is equally follows:

Pinout Diagram of a 4001 Quad NOR DIP-format IC

1 Input A1 2 Input B1 iii Output Q1 4 Output Q2 v Input B2 six Input A2 vii 5ss 8 Input A3 9 Input B3 ten Output Q3 11 Output Q4 12 Input B4 13 Input A4 xiv 5dd

Availability [edit]

These devices are available from virtually semiconductor manufacturers such as Fairchild Semiconductor, Philips or Texas Instruments. These are normally bachelor in both through-hole DIP and SOIC format. Datasheets are readily bachelor in most datasheet databases.

In the pop CMOS and TTL logic families, NOR gates with upward to 8 inputs are available:

• CMOS
  • 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 ii-input NOR gate
  • 7427: Triple 3-input NOR gate
  • 7425: Dual 4-input NOR gate (with strobe, obsolete)
  • 74260: Dual v-Input NOR Gate
  • 744078: Single eight-input NOR Gate

In the older RTL and ECL families, NOR gates were efficient and about normally used.

Implementations [edit]

PMOS NOR gate with load resistor.

The diagrams above show the structure of a 2-input NOR gate using NMOS logic circuitry. If either of the inputs is high, the respective Northward-aqueduct MOSFET is turned on and the output is pulled low; otherwise the output is pulled loftier through the pull-up resistor.

The diagram below shows a 2-input NOR gate using CMOS technology. The diodes and resistors on the inputs are to protect the CMOS components from damage due to electrostatic discharge (ESD) and play no part in the logical function of the excursion.

Unbuffered CMOS two input NOR gate

Functional completeness [edit]

The NOR gate has the property of functional abyss, which it shares with the NAND gate. That is, any other logic function (AND, OR, etc.) can be implemented using but NOR gates.^[2] An entire processor tin be created using NOR gates lonely.

As NAND gates are too functionally complete, if no specific NOR gates are available, one can exist made from NAND gates using NAND logic.^[2]

Desired gate	NAND Construction

See besides [edit]

• AND gate
• OR gate
• Non gate
• NAND gate
• XOR gate
• XNOR gate
• NAND logic
• Boolean algebra (logic)
• Flash memory

References [edit]

1. ^ Whipple, Walt (2019). First-Paw:Hacking Apollo'south Guidance Computer. Applied science and Applied science History Wiki.
2. ^ ^{a b} Mano, K. Morris and Charles R. Kime. Logic and Reckoner Pattern Fundamentals, Tertiary Edition. Prentice Hall, 2004. p. 73.

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Source: https://en.wikipedia.org/wiki/NOR_gate

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