# Logic Gates Logic gates are switches in circuits that perform an operation based on some input.

A NOT gate outputs the opposite of the input. It is indicated by an arrow pointing parallel to the circuit wire with a small circle at its tip.

An AND gate accepts two inputs. Its output is true when both its inputs are. An AND gate is drawn as a capital D, with two wires entering the flat side and one wire exiting the curved side.

A Not AND gate accepts two or more inputs. Its output is only false when all its inputs are true. Its symbol is the same as an AND gate, but with a small circle connecting the curved side and the line exiting it.

An OR gate can take two or more inputs. Its output will be true if one or more of its inputs are true. Its symbol is a capital D with a concave “flat” side. Two wires enter the concave side; one exits the other side.

A NOR gate can take two or more inputs. It will output TRUE only when none of the inputs are true. Its symbol is the same as that of the OR gate, but with a small circle connecting the exiting wire and the D.

An EX-OR gate accepts two inputs, and outputs true when one is false and one is true. Its symbol is the same as the NOR gate, but with a double line on the concave side.

An EX-NOR gate accepts two inputs, and outputs true when both are false or both are true. Its symbol is the same as an EX-OR gate, but with a small circle connecting the exit wire and the D.