Microprogram Control Unit As discussed in Control Unit  topic, a control unit generates a binary control variable for executing a particular microoperations. The control unit can be a hardwired or microprogrammed control unit. A control word can be programmed to perform various operations on components of the system. A control unit whose control word is stored in the control memory which is usually a ROM is called as microprogram control unit.  Each control word in the control memory contains within it a microinstruction. Every microinstruction specifies one or more micro-operations. A microprogram is written for every instruction supported by the CPU. Each instruction of a program causes the corresponding micro-program to be fetched and its control information extracted in a manner that resembles the