Vertical microprogramming mutually exclusive

Question

A Hypothetical control unit supports 5 groups of mutually exclusive signals

G1:2

G2:1

G3:4

G4:33

G5:25

What is the size of control memory (in bytes), if during any microinstruction atmost 1 control signal is active and the control unit support 256 control word memory?

 

My approach;

8(256cw)+(2+1+3+6+5) bits=25bits

The total size is 25*256/8bytes

Answer key

8+(1+1+2+6+5)=23bits

For all the groups either 1 of the signals can be active or none also right? That is the meaning of mutually exclusive right?

Am I correct?

@arjun sir?

Comments

okkkk okk got it :)  next address means memory total  i am not counting that

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But how to make both signals in group not active.Mutually exclusive means both may not occur right?

For eg I have a Ip signal and Op signal to a register. They are mutually exclusive in the sense that either one of them can be active not both.But both Ip and Op can take value 0 simultaneously, because I dont want to use the register sometimes.

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mutually exclusive here means that in a group only 1 signal will be active at a time.