Just a question

Thread Starter

aceminer

Joined Aug 26, 2011
21
Hi guys,

Just to check, is there any exam papers i could find on the net provided with solutions as my digital logic exam is just round the corner. Would appreciate greatly any material or exam papers. I am a Year 1 CS student anyway.
 

Thread Starter

aceminer

Joined Aug 26, 2011
21
Hey bertus, thanks for the link but they are apparently too hard for me to understand. I am only a Year 1 student so the course i am undergoing is relatively introductory so do you have any other links which are relatively less complicated. To be honest, i couldnt even understand the questions or the answers in the worksheet.
 

thatoneguy

Joined Feb 19, 2009
6,359
Hey bertus, thanks for the link but they are apparently too hard for me to understand. I am only a Year 1 student so the course i am undergoing is relatively introductory so do you have any other links which are relatively less complicated. To be honest, i couldnt even understand the questions or the answers in the worksheet.
Everything in the worksheet and quiz is covered in the link I posted.
 

Thread Starter

aceminer

Joined Aug 26, 2011
21
Well i have a question which goes like this:

Given an Equation :
F = A'B'CD' + B'C'D + A'B'C' + AB'D
use a 4x1 multiplexer with an enable input plus other gates
draw out the circuit based on this equation. Anyway the enable is active-low.

I do have the answer but i cannot seem to understand why do they use A and C inputs as the select bits whereas the D inputs are belonging to the 4 x 1 multiplexer with one input being constant. Could some1 kindly please explain to me.
 

thatoneguy

Joined Feb 19, 2009
6,359
Skip to Here and draw out the truth table for the expression.

From there, look at the behavior of a 4-1 multiplexer with enable.

The ' as in A' means NOT A, and AB means A AND B, A+B is A OR B, and A'B is NOT A AND B

It's just a system of notation for text discussion of logic.
 
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