Symbols

There are two symbols of OR gates: the American (ANSI or 'military') symbol and the IEC ('European' or 'rectangular') symbol, as well as the deprecated DIN symbol.^[2][3] For more information see Logic Gate Symbols.

MIL/ANSI Symbol	IEC Symbol	DIN Symbol

This schematic diagram shows the arrangement of four OR gates within a standard 4071 CMOS integrated circuit.

Hardware description and pinout

OR Gates are basic logic gates, and as such they are available in TTL and CMOS ICs logic families. The standard 4000 series CMOS IC is the 4071, which includes four independent two-input OR gates. The ancestral TTL device is the 7432. There are many offshoots of the original 7432 OR gate, all having 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

Variations include:

• 74LS32: Quad 2-input OR gate (low power Schottky version)
• 74HC32: Quad 2-input OR gate (high speed CMOS version) - has lower current consumption/wider voltage range
• 74AC32: Quad 2-input OR gate (advanced CMOS version) - similar to 74HC32, but with significantly faster switching speeds and stronger drive
• 74LVC32: Low voltage CMOS version of the same.

Implementations

CMOS OR gate

NMOS OR gate

BJT OR gate

OR gate using diodes

Alternatives

If no specific OR gates are available, one can be made from NAND or NOR gates in the configuration shown in the image below. Any logic gate can be made from a combination of NAND or NOR gates.

NAND Construction	NOR construction

Wired-OR

Wired OR gate using open-collector NOR gates

With active low 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.