In case of horizontal organization, the implementation is simple, but in case of vertical organization, implementation complexity increases due to the required decoder circuits. Also the complexity of decoder depends on the level of grouping and encoding of the control signal.

Horizontal and Vertical organization represent the two organizational extremes in microprogrammed control. Many intermediate schemes are also possible, where the degree of encoding is a design parameter.

We will explain the grouping of control signal with the help of an example. Grouping of control signals depends on the internal organization of CPU.

Assigning individual bits to each control signal is certain to lead to long microinstruction, since the number of required control signals is normally large.

However, only a few bits are set to 1 and therefore used for active gating in any given microinstructions. This obviously results in low utilization of the available bit space.

If we group the control signal in some non-over lapping group then the size of control word reduces.