# Help with 8-1 Multiplexer

Discussion in 'Homework Help' started by ITNetAngel, Jul 8, 2011.

1. ### ITNetAngel Thread Starter New Member

Jul 8, 2011
4
0
a) Draw a logic diagram of an 8-1 multiplexer with eight 4-bit inputs and three control signals:
Inputs: I0 = 0000 Select signals:
I1 = 0100 S2
I2 = 0010 S1
I3 = 0001 S0
I4 = 1111
I5 = 1011
I6 = 1101
I7 = 1110
Note: Each output will be one of the 4-bit inputs as determined by the select signals.

b) For the 8-to-1 multiplexer above, draw a truth table showing the 4-bit outputs for each of the 8 input possibilities

Select Signals
Output
S2
S1
S0
0​
0​
0​
0000​
1​
1​
1​

2. ### guitarguy12387 Active Member

Apr 10, 2008
359
12
Hey and welcome to the forums.

But you should know... while we're happy to help, we won't just do your homework for you. You need to post your attempted solution with specific questions. At which point, we can help you.

3. ### Georacer Moderator

Nov 25, 2009
5,151
1,266
You might want to indent your data a bit better too, to help others understand what you are saying. I take it you mean to write that the inputs are:
I0 = 0000
I1 = 0100
I2 = 0010
I3 = 0001
I4 = 1111
I5 = 1011
I6 = 1101
I7 = 1110

The select signals are:
S1,S2 and S3

And you should have four truth tables, one for each output bit, with the layout:
Inputs__________________|__Output
Input bit | Select bits (1,2,3) | Output bit