The preceding paragraph discusses microinstruction design from the microprogrammer’s
point of view. But the degree of encoding also can be viewed from its
hardware effects.With a pure unencoded format, little or no decode logic is needed;
each bit generates a particular control signal.As more compact and more aggregated
encoding schemes are used, more complex decode logic is needed.This, in turn, may
affect performance. More time is needed to propagate signals through the gates of
the more complex control logic module. Thus, the execution of encoded microinstructions
takes longer than the execution of unencoded ones.