Q. Calculate Register Transfer Time?

A clock isn't included explicitly in any statements discussed above. But it is presumed that all transfers take place during clock edge transition instantly following the period when control function is 1. All statements suggest ahardware construction for implementing the micro-operation statement as shown below:

Implementation of controlled data-transfer from R2 to R1 only when T = 1

       T:     R1 ← R2 

Figure: The Register Transfer Time

It is presumed that control variable is synchronized with the same clock as the one applied to the register. The control function T is triggered by rising edge of the clock pulse at time t. Even though control variable T becomes active just after time t, the actual transfer doesn't happen till the register is activated by next positive transition of clock at time t+1. At time t+1 load input is again active and data inputs of R2 are then loaded in the register R1 in parallel. The transfer takes place with each clock pulse transition while T remains active.