Q. Explain Hardwired control organization?

In the hardwired organization control unit is designed as a combinational circuit. The control unit is applied by gates, flip-flops, decoder and other digital circuits. Hardwired control units can be optimised for fast operations. Block diagram of control unit is displayed in Figure below. Major inputs to circuit are instruction register, clock, and flags. Control unit uses the opcode of instruction stored in IR register to perform various actions for various instructions. The Cu logic has unique logic input for every opcode. It simplifies the control logic. This control line selection can be executed by a decoder.

A decoder will have n binary inputs and 2ⁿ binary outputs. Every one of these 2ⁿ different input patterns will trigger a single unique output line. 

Clock part of the control unit issues a repetitive sequence of pulses for SS duration of micro-operation(s). These timing signals control the sequence of execution of instruction as well as determine what control signal requires to applied at what time for instruction execution. 

Figure: Block Diagram of Control Unit Operation