register transfer operations

Could you help me with this task? I'm confused about the control variables K1,K2 ...
K2 have to activate the comparator or to activate the register R3?


Draw the hardware diagram for the implementation of the following register transfer operations:

K1.K2 : if (R1< R2) R3 \leftarrow R1
K1.K2’ : R3 \leftarrow R1+R2

( Show the comparator circuit as a box.)

We have absolutely no idea what you're talking about, you posted not a single piece of information about the circuit you're using.