MUX assignment question

Discussion in 'Homework Help' started by en1gma, Feb 22, 2013.

1. en1gma Thread Starter New Member

Feb 6, 2013
19
0
hello all,

for the assignment we are required to create a 4-1 mux using ONLY tri-state buffers. I have attatched my current diagram... I am new to circuits and would like to know how to verify my circuit is working correctly. We are using logicworks 5.

a. This MUX should have two selector lines S0 and S1 and four input lines A-D.
b. The output should match the following table:
S1 S0 || OUTPUT
0 0 || A
0 1 || B
1 0 || C
1 1 || D
In other words, when S0 and S1 are both zero the MUX will select input A for use as the output.

THANKS!

2. en1gma Thread Starter New Member

Feb 6, 2013
19
0
here is the diagram ... I believe, or hope, my logic is correct, but as I said, how can i test it in logic works5?

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3. WBahn Moderator

Mar 31, 2012
18,085
4,917
I don't see how it can be done. Consider the case in which both of your select lines are 0. How can you turn on ANY of the tri-state buffers?

4. WBahn Moderator

Mar 31, 2012
18,085
4,917
You are using things other than tri-state buffers, which violates the constraint you had capitalized in your first post.

So which is it? What are the design constraints?

5. en1gma Thread Starter New Member

Feb 6, 2013
19
0
My mistake, we can use tri-state buffers and inverters as well. Here is the full problem statement.

1. Create a 4-1 MUX using ONLY tri-state buffers and inverters in LogicWorks. This circuit will select one output from four inputs based on two addition switches. Please read textbook page 131 section 3-9 Multiplexers before implementing this lab assignment. You can test out your circuit using binary switches and a Hex keyboard

Hope this clears the confusion. Thanks again!

6. WBahn Moderator

Mar 31, 2012
18,085
4,917
In that case, your circuit looks fine. As for testing it in Logicworks 5, I have no idea -- I've never used it. Good luck.