>
> For question 5.38...
>
> I do not see the difference between setting EN2 or EN3 as grounded or
> active because no matter which one is grounded, the other pin will act as
> an enable and has no advantages or disadvantages over the other.
>
> I dunno, because if you ground an active low-input, that is the same as
> pulling-high as EN1 correct? So there is no difference, only one of the
> decoders will output a non-zero value (i.e. 1 of the four bytes will be
> non-zero).
Wilson:
The problem here is that you are only thinking about the logic operation
of the circuit. Each solutiong (setting EN2 or EN3 to ground) has both
advantages and disadvantages that you are suppose to identify.
You should be thinking about propagation delay and about the amount
of load that the incoming enable signal "sees" when it arrives at
your design.
The more gates a signal has to change (i.e. the more gates a signal
is input of), the stronger the signal has to be to ensure proper
operation of your design.
Cheers,
Nelson
/
\ / / Jose Nelson Amaral - amaral@cs.ualberta.ca
) / ( Associate Professor
/ / \ Dept. of Computing Science - University of Alberta
( / ) Edmonton, Alberta, Canada, T6G 2E8
\ O / Phone: (780)492-5411 Fax: (780)492-1071
\ / http://www.cs.ualberta.ca/~amaral
`----'
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