Besides the six basic
gates, there are two exclusive gates, the exclusive-OR
(XOR) and the exclusive-NOR (XNOR).
The XOR gate has a High output when
the inputs are unequal, opposite or different (one High
and one Low). The XNOR
gate, on the other hand, is reverse; its an equality
gate. It says if both inputs are the
same (both Low or both High), the output is High; otherwise
the output is Low.
Exclusive gates are used in comparator,
controlled inverter, adder and phase
detector circuits, to name a few application.