Co control word

Question

The control field of a microinstruction supports 2 groups of control signals in which G1 indicates none or one of a 256 control signals and G2 indicates atmost 6 signals from the remaining. 

What is the size of the control field in the instruction?

Comments

14?

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how  ?

 

cn u explain?

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 G1 indicates none or one of a 256 control signals it means we can select atmost one signal it clearly indicates that we have to use vertical instruction format = log256 =8bits

 and G2 indicates atmost 6 signals from the remaining means we can select either o or 1 or 2......6 signals for which we need to use horizontal instruction format. = 6bits

therefore ,  total cf size =8+6 bits = 14bits.  

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in both the groups u are given similar condition so why u used vertical in one and horizontal in the other

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none or one means you can use only one at max. from 256 signals which is possible only for vertical mic.pr..

and atmost 6 means you can use entire 6 signals at one go.. can be done only by horizontal mic pr.

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but when u have to use horizontal  then u have to use all line na .

 then how  would  you select  6  line from 256?

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@arvin

in horizontal micro programming we do not use encoded format to represent the signal

so how 6 bits ?

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@Satbir brother for horizontal programming there is no need for a decoder but we need a decoder for vertical..!

@hitendra singh brother you not getting my point.. :/

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ya I don't know what point are u trying to make ?

 

but when u have to use horizontal  then u have to use all line na .

 then how  would  you select  6  line from 256?

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So we need 1 bit to represent each signal in horizontal micro programming ? thats why it is 6 bits @arvin

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@Satbir did u get the point what @arvin is trying to put there

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@hitendra singh see that 256 bits are reserved for the vertical signals .. and from the remaining means other signals and you cannot use that from remaining 256 signals.. read it carefully... 

from the question : it will have total 256+6 cs = 262 signals where 256 are fixed for vertical and 6 for horizontal...

@Satbir yes bro each bit will represent a signal in horizontal mic prog..

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I think question  is little bit wrong question says that 

2 groups of control signals in which G1 indicates none or one of a 256 control signals and G2 indicates atmost 6 signals from the remaining .

 G2 indicates atmost 6 signals from the remaining .What do you think from the word remaining ?

I think remaining means 255.

Although i get it what you have suggested but at least give it a thought.

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G1 indicates none or one of a 256 control signals

G2 indicates atmost 6 signals from the remaining  

These are 2 different statements. remaining could be anything but we have to be concerned with only 6 signals that are mentioned for G2.