Reversible Control Unit
Hafiz Md. Hasan Babu · 2020
A control unit consists of two decoders, a sequence counter, and a number of control logic gates. It fetches the instruction from instruction register. This chapter presents the reversible implementation of different components of the control unit. It introduces two reversible gates, such as HL gate and BJ gate, that are used to design decoder and JK flip-flop. The chapter describes the design of a 4-bit sequence counter that counts from 0 to 15. The sequence counter is designed using four JK flip-flops and four Feynman gates. The JK flip-flops change states with the positive clock edge and the counter counts from 0 to 15. Finally, the chapter illustrates the construction procedure and the complexities of the reversible control unit. Some properties on the numbers of gates and garbage outputs of the control unit are also presented.