used in reversible computation
. Has 3 input
- Inputs A1 and A2 are control lines, and are copied unchanged to outputs A1' and A2'.
- Input B is the data line; it is copied unchanged to output B' if A1=0 or A2=0, otherwise it is inverted on B'.
In conventional terms, A1'=A1, A2'=A2 and B'=B xor
The controlled controlled not gate is universal: you can build computers using just this gate.