TYPES OF MICROINSTRUCTIONS

   

           In the microprogrammed control units all the control signals associated with microoperations are stored in special memory called control memory .

          Set of control signals that cause microoperations to occur is called microinstructions . 

         Micro-programmed control unit can be classified into two types based on the type of Control Word(microinstructions) stored in the Control Memory . 

Horizontal micro-programmed control unit  

Vertical micro-programmed control unit

In Horizontal micro-programmed control unit, the control signals are represented in the decoded binary format.

                   ‘n’ control signals require n bit encoding i.e., 1 bit/CS. 

In Vertical micro-programmed control unit, the control signals are represented in the encoded binary format.

                    ‘n’ control signals require log2n bit encoding.