Registers

Need to choose inputs: hold or parallel load

Use 2-1 MUX

Hold: need to keep value constant

D flip-flop sets Q to value of D

feed Q back to 0 input of MUX

Parallel load: set flip-flop value to input

feed input x to 1 input of MUX

Also need clock and control input

(Note that control is shown going

through each MUX)