Hardwired Control Unit

1. It is implemented with the help of gates, flip flops, decoders etc. in the hardware. The inputs to control unit are the instruction register, flags, timing signals etc. This organization can be very complicated if we have to make the control unit large. If the design has to be modified or changed, all the combinational circuits have to be modified which is a very difficult task.
2. Hardwired control units are generally faster. 
3. The relationship between control inputs and control outputs is a series of Boolean functions.