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==Application in digital circuit design==
One application of Boolean algebra is digital circuit design, with one goal to minimize the number of gates and another to minimize the settling time.

There are sixteen possible functions of two variables, but in digital logic hardware, the simplest gate circuits implement only four of them: ''[[logical conjunction|conjunction]]'' (AND), ''[[logical disjunction|disjunction]]'' (inclusive OR), and the respective complements of those (NAND and NOR).

Most gate circuits accept more than 2 input variables; for example, the spaceborne [[Apollo Guidance Computer]], which pioneered the application of integrated circuits in the 1960s, was built with only one type of gate, a 3-input NOR, whose output is true only when all 3 inputs are false.<ref>{{cite book |first= Eldon C. |last= Hall |title= Journey to the Moon: The History of the Apollo Guidance Computer |publisher= AIAA |date= 1996 |isbn= 1-56347-185-X }}</ref>{{page needed|date=December 2019}}<ref>{{cite web|url=http://klabs.org/history/ech/agc_schematics/index.htm|title=APOLLO GUIDANCE COMPUTER (AGC) Schematics|website=klabs.org|publisher=Rich Katz|access-date=2021-06-19|quote=To see how NOR gate logic was used in the Apollo Guidance Computer's ALU, select any of the 4-BIT MODULE entries in the Index to Drawings, and expand images as desired.}}</ref>