Question

Difference between horizontal and vertical microinstruction

Answer 1

Horizontal MicroinstructionVertical Microinstruction1Horizontal microinstruction format is minimal encoded scheme in which many resources can be controlled with single MicroinstructionVertical microinstruction format use compact codes to specify control functions in each Microinstruction2Horizontal approach is useful when higher operating speed is desired and when machine structure allows parallel use of resources.Vertical approach results in considerably slower operating speeds because more microinstructions are needed to perform the desired control functions3Wide memory wordWidth is narrow: ncontrol signals can be encoded into log2n control bits.4May or may not require to decode the instruction.Must require to decode instruction number of times

Answer 2

Horizontal microinstruction:

It is the one type of control unit, where the “control signals” are used to decode the binary format  

It does not require any hardware and it supports longer control code. It is less flexible.

Vertical microinstruction:

It is also a type of control unit where the “control signals” are used to encode the binary format.

It requires hardware and it supports smaller control code. It is more flexible when compared to the horizontal micro instruction.