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Encyclopedia > XOR gate
INPUT
A   B
OUTPUT
A XOR B
0 0 0
0 1 1
1 0 1
1 1 0

The XOR gate is a digital logic gate that implements exclusive disjunction - it behaves according to the truth table to the right. A HIGH output (1) results if one, and only one, of the inputs to the gate is HIGH (1). If both inputs are LOW (0) or both are HIGH (1), a LOW output (0) results. Exclusive disjunction, also known as exclusive or and symbolized by XOR or EOR, is a logical operation on two operands that results in a logical value of true if and only if one of the operands, but not both, has a value of true. ... XOR may mean: Exclusive or (logic) XOR gate XOR (computer game) XOR (x86 instruction): see x86 instruction listings Category: ... A logic gate performs a logical operation on one or more logic inputs and produces a single logic output. ... Exclusive disjunction, also known as exclusive or and symbolized by XOR or EOR, is a logical operation on two operands that results in a logical value of true if and only if one of the operands, but not both, has a value of true. ...


This function is addition modulo 2. As a result, XOR gates are used to implement binary addition in computers. A half adder consists of an XOR gate and an AND gate.
This article or section should include material from ALU adder In electronics, an adder is a device which will perform the addition, S, of two numbers. ... Media:Example. ...

Contents

Symbols

There are two symbols for XOR gates: the 'military' symbol and the 'rectangular' symbol. For more information see Logic Gate Symbols A logic gate performs a logical operation on one or more logic inputs and produces a single logic output. ...

'Military' XOR Symbol
'Military' XOR Symbol
'Rectangular' XOR Symbol
'Rectangular' XOR Symbol


A XOR B= A.(/B) +(/A).B Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ...

 where /A represents NOT A 

Hardware description and pinout

XOR gates are basic logic gates, and as such they are recognised in TTL and CMOS ICs. The standard, 4000 series, CMOS IC is the 4070, which includes four independent, two-input, XOR gates. The 4070 replaces the less reliable 4030, but keeps the pinout. The pinout diagram is as follows: TTL is an elite band of men and boys that originate, live or are involved in the tadley bmx scene. ... For other uses, see CMOS (disambiguation). ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ...

 1 Input A1 2 Input B1 3 Output Q1 4 Input A2 5 Input B2 6 Output Q2 7 VG 8 Input A3 9 Input B3 10 Output Q3 11 Input AA 12 Input B4 13 Output Q4 14 VCC 

This device is available from most semiconductor manufacturers such as Philips. It is usually available in both through-hole DIL and SOIC format. Datasheets are readily available in most Datasheet Databases. ICs in DIP14-Package Several PDIPs and CERDIPS. The large CERDIP in the foreground is an 8080 processor. ... Small-Outline Integrated Circuit (SOIC). ... A datasheet is a document summarizing the performance and other characteristics of a component (e. ...


Alternatives

If no specific XOR gates are available, one can be made from four NAND or five NOR gates in the configurations shown below.

XOR gate constructed using only NAND gates
XOR gate constructed using only NOR gates
XOR gate constructed using only NOR gates


Image File history File links No higher resolution available. ... Image File history File links NOR_XOR.PNG Summary Made in Good Ol Paint and Crocodile Technology Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): User:Sceptre NOR logic ...


More than two inputs

The XOR operation is a binary operation and is therefore defined only for two inputs. [1] It is nevertheless common in electronic design to talk of "XORing" three or more signals. In mathematics, a binary operation is a calculation involving two input quantities, in other words, an operation whose arity is two. ...


The most common interpretation of this usage is that the first two signals are fed into an XOR gate, then the output of that gate is fed into a second XOR gate together with the third signal, and so on for any remaining signals. The result is a circuit that outputs a 1 when the number of 1s at its inputs is odd, and a 0 when the number of incoming 1s is even. This makes it practically useful as a parity generator or a modulo-2 adder. In the usage in telecommunication, the number of 1 bits in the binary value is counted. ... In electronics, an adder is a device which will perform the addition, S, of two numbers. ...

A second interpretation is also possible, based on both the linguistic sense of the term "exclusive OR" and the IEC symbol for an XOR gate (see right). This interpretation states that the output is 1 when one or other of the inputs, exclusively, is 1. The "=1" in the IEC symbol implies the same thing. However, the IEC symbol was not intended to be modified by adding further inputs, and becomes invalid when this is done. This interpretation is rarely used in electronics, since parity generators and adders are in more common use than "1 of n" detectors. Image File history File links Three_ones_EORed. ...


See also

The XNOR gate is a digital logic gate whose function is the inverse of the exclusive OR (XOR) gate. ... Boolean algebra is the finitary algebra of two values. ... A logic gate is an arrangement of electronically-controlled switches used to calculate operations in Boolean algebra. ...

References

  1. ^ "exclusive OR n." The Concise Oxford English Dictionary, Eleventh edition revised . Ed. Catherine Soanes and Angus Stevenson. Oxford University Press, 2006. Oxford Reference Online. Oxford University Press. Birmingham City Council. 27 May 2007 [1]

  Results from FactBites:
 
Exclusive disjunction - Wikipedia, the free encyclopedia (969 words)
In view of the isomorphism between addition modulo 2 and exclusive disjunction, it is clear that XOR is both an associative and a commutative operation.
XOR is also used to detect an overflow in the result of a signed binary arithmetic operation.
XOR can be used to swap two numeric variables in computers, using the XOR swap algorithm; however this is regarded as more of a curiosity and not encouraged in practice.
Logic Gates (1347 words)
This is a diagram of a NOT gate.
This is not ambiguous because the XOR function is associative (all parenthesization of this expression are equivalent).
Although the output of a gate may be attached to more than one input, an input may not have two different outputs attached to it (this would create conflicting input signals).
  More results at FactBites »

 
 

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