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 is an idealized or physical device implementing a Boolean function, that is, it performs a logical operation on one or more logic inputs and produces a single logic output. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and...

 that implements logical disjunction

Logical disjunction

In logic and mathematics, a two-place logical connective or, is a logical disjunction, also known as inclusive disjunction or alternation, that results in true whenever one or more of its operands are true. E.g. in this context, "A or B" is true if A is true, or if B is true, or if both A and B are...

 - 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 expressions on each of their functional arguments, that is, on each combination of values taken by their...

 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. In another sense, the function of OR effectively finds the maximum between two binary digits, just as the complementary AND function finds the minimum.

Symbols

There are three symbols for OR gates: the American (ANSI or 'military') symbol and the IEC ('European' or 'rectangular') symbol, as well as the deprecated DIN

Din

DIN or Din or din can have several meanings:* A din is a loud noise.* Dīn, an Arabic term meaning "religion" or "way of life".* Din is one of the ten aspects of the Ein Sof in Kabbalah ....

 symbol. For more information see Logic Gate Symbols.

MIL/ANSI Symbol	IEC Symbol	DIN Symbol

Hardware description and pinout

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

Integrated circuit

An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

 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 compatible logic levels and power supply...

. The standard 4000 series CMOS

CMOS

Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...

 IC is the 4071, which includes four independent two-input OR gates. The traditional TTL version is the 7432. There are many offshoots of the original 7432 OR gate. All have the same pinout but different internal architecture, allowing them to operate in different voltage ranges and/or at higher speeds. In addition to the standard 2-Input OR Gate, 3- and 4-Input OR Gates are also available. In the CMOS series, these are:

• 4075: Triple 3-Input OR Gate
• 4072: Dual 4-Input OR Gate

TTL variations include:

• 74LS32: Quad 2-input OR gate (Low power Schottky
  Schottky barrier
  A Schottky barrier, named after Walter H. Schottky, is a potential barrier formed at a metal–semiconductor junction which has rectifying characteristics, suitable for use as a diode...
  
   version)
• 74HC32: Quad 2-input OR gate (High Speed CMOS version) - has lower current consumption/wider Voltage range
• 74LVC32: Low voltage CMOS version of the same.

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". However, modern integrated circuits are not constructed exclusively from a single type of gate...

Wired-OR

With active low

Logic level

In digital circuits, a logic level is one of a finite number of states that a 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 basic 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 . If neither or only one input to the AND gate is HIGH, a LOW output results...
  
  
• NOT gate
• NAND gate
  NAND gate
  The Negated AND, NO AND or NAND gate is the opposite of the digital AND gate, and behaves in a manner that corresponds to the opposite of AND gate, as shown in the truth table on the right. 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 . If one or both input is HIGH , a LOW output results. NOR is the result of the negation of the OR operator...
  
  
• XOR gate
  XOR gate
  The XOR gate is a digital logic gate that implements an exclusive or; that is, a true output results if one, and only one, of the inputs to the gate is true . If both inputs are false or both are true , a false output results. Its behavior is summarized in the truth table shown on the right...
  
  
• Boolean algebra (logic)
• Logic gates