Binary-coded modulo-seven negator
Zigmantas L. Budrikis, Antonio Cantoni, R.R. Perry · Electronics Letters · 1971
A circuit consisting of four NOR gates multiplies modulo-seven integers, represented by binary digits on three input lines, by six. In modulo-seven arithmetic, this is equivalent to negation, and the circuit is a negator. Negators, together with standard flip-flops and half adders, yield all primitive components needed for binary-coded modulo-seven linear sequential networks.