The structure of control unit can be represented in a simplified view by putting it in block diagram. The detailed hardware involved may be explored step by step. The simplified view of the control unit is given in the Figure 5.10.

The decoder/encoder block is simply a combinational circuit that generates the required control outputs depending on the state of all its input.

The decoder part of decoder/encoder part provide a separate signal line for each control step, or time slot in the control sequence. Similarly, the output of the instructor decoder consists of a separate line for each machine instruction loaded in the IR, one of the output line INS₁  to  INS_m  is set to 1 and all other lines are set to 0.            

The detailed view of the control unit organization is shown in the Figure 5.11.