Question

An instruction set of a processor has $125$ signals which can be divided into $5$ groups of mutually exclusive signals as follows:

Group $1:20$ signals, Group $2:70$ signals, Group $3:2$ signals, Group $4:10$ signals, Group $5:23$ signals

How many bits of the control words can be saved by using vertical microprogramming over horizontal microprogramming?

• A. $103$
• B. $0$
• C. $55$
• D. $22$

Answer 1

The correct option is A $103$

In horizontal form signals are present in decoded form. So number of signal bits

$=20+70+2+10+23$
$=125bits$

In vertical form signals are present in encoded form. So, number of signal bits:

$=log\left(20\right)+log\left(70\right)+log\left(2\right)+log\left(10\right)+log\left(23\right)$
$=5+7+1+4+5=22$

So, total bits saved using vertical form
$=125-22=103bits$