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The OR gate is a digital logic gate
Logic gate

A logic gate performs a logical operation on one or more logic inputs and produces a single logic output. The logic normally performed is Boolean logic and is most commonly found in digital circuits....
 that implements logical disjunction
Logical disjunction

File:ORGate2.pngIn logic and mathematics, or, also known as logical disjunction or inclusive disjunction is a logical operator that results in true whenever one or more of its operands are true....
 - it behaves according to the truth table
Truth table

A truth table is a mathematical table used in logic?specifically in connection with Boolean algebra , boolean functions, and propositional calculus?to compute the functional values of logical expression s on each of their functional arguments, that is, on each combination of values taken by their logical variables....
 to the right.






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Encyclopedia


INPUT
A   B 		OUTPUT
A + B
0 0 0
0 1 1
1 0 1
1 1 1


The OR gate is a digital logic gate
Logic gate

A logic gate performs a logical operation on one or more logic inputs and produces a single logic output. The logic normally performed is Boolean logic and is most commonly found in digital circuits....
 that implements logical disjunction
Logical disjunction

File:ORGate2.pngIn logic and mathematics, or, also known as logical disjunction or inclusive disjunction is a logical operator that results in true whenever one or more of its operands are true....
 - it behaves according to the truth table
Truth table

A truth table is a mathematical table used in logic?specifically in connection with Boolean algebra , boolean functions, and propositional calculus?to compute the functional values of logical expression s on each of their functional arguments, that is, on each combination of values taken by their logical variables....
 to the right. A HIGH output (1) results if one or both the inputs to the gate are HIGH (1). If neither input is HIGH, a LOW output (0) results.




Symbols


There are two symbols for OR gates: the 'military' symbol and the 'rectangular' symbol. For more information see Logic Gate Symbols
Logic gate

A logic gate performs a logical operation on one or more logic inputs and produces a single logic output. The logic normally performed is Boolean logic and is most commonly found in digital circuits....


Or Gate En


Hardware description and pinout


OR Gates are basic logic gates, and as such they are available in TTL
TTL

The abbreviation TTL can refer to:* Transistor?transistor logic, a type of digital logic-gate circuits* Time to live for computer data* Through-the-lens metering in photography...
 and CMOS
CMOS

Complementary metal?oxide?semiconductor , is a major class of integrated circuits. CMOS technology is used in microprocessors, microcontrollers, Static Random Access Memory, and other digital logic circuits....
 IC
Integrated circuit

In electronics, an integrated circuit is a miniaturized electronic circuit that has been manufactured in the surface of a thin Wafer of semiconductor material....
s logic families
Logic family

In computer engineering, a logic family may refer to one of two related concepts. A logic family of monolithic digital integrated circuit devices is a group of electronic logic gates constructed using one of several different designs, usually with input/output standards and power supply characteristics within a family....
. The standard, 4000 series, CMOS IC is the 4071, which includes four independent, two-input, OR gates. As well as the standard 2-Input OR Gate, 3- and 4-Input OR Gates are also available:
  • 4075: Triple 3-Input OR Gate
  • 4072: Dual 4-Input OR Gate


TTL:
  • 74LS32: Quad 2-input OR gate


hardware description language


module(a,b,c); input a,b; output c; or (c,a,b); end module;

Implementations



Alternatives


If no specific OR gates are available, one can be made from NAND gates in the configuration shown below. Any logic gate can be made from a combination of NAND gates
NAND logic

NAND gates are one of the two basic logic gates from which any other logic gates can be built. Due to this property, NAND and NOR gates are sometimes called "universal gates"....


Wired-OR


With active low
Logic level

In digital circuits, a logic level is one of a finite number of states that a digital signal can have. Logic levels are usually represented by the voltage difference between the signal and Ground , although other standards exist....
 open-collector logic outputs, as used for control signals in many circuits, an OR function can be produced by wiring together several outputs. This arrangement is called a wired OR. This implementation of an OR function typically is also found in integrated circuits of N or P-type only transistor processes.

See also

  • AND gate
    AND gate

    The AND gate is a digital logic gate that implements logical conjunction - it behaves according to the truth table to the right. A HIGH output results only if both the inputs to the AND gate are HIGH ....
  • NOT gate
  • NAND gate
    NAND gate

    The NAND gate is a digital logic gate that behaves in a manner that corresponds to the truth table to the left. A LOW output results only if both the inputs to the gate are HIGH....
  • NOR gate
    NOR gate

    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 results if both the inputs to the gate are LOW ....
  • XOR gate
    XOR gate

    The XOR gate is a digital logic gate that implements exclusive disjunction - it behaves according to the truth table above. A HIGH output results if one, and only one, of the inputs to the gate is HIGH ....
  • Boolean algebra (logic)
  • Logic gates