# problem with multiplexer implementation

Discussion in 'Homework Help' started by ambageo, Dec 16, 2011.

1. ### ambageo Thread Starter New Member

Dec 16, 2011
4
0
Hi to all of you! I'm a newbie in this forum, and,as you already guessed, I need help in order to understand something:
I have a function, f, and below is the truth table of it:
D3 D2 D1 D0 f
0 0 0 0 0
0 0 0 1 1
0 0 1 0 1
0 0 1 1 0
0 1 0 0 0
0 1 0 1 0
0 1 1 0 0
0 1 1 1 1
1 0 0 0 1
1 0 0 1 1
1 0 1 0 1
1 0 1 1 1
1 1 0 0 1

D3 D2 D1 D0 is the binary form of a decimal number, so e.g (1 0 1 0) is the binary form of 10 etc.
I am only interested in numbers from 0 to 12. I am not interested at all for 13,14 and 15. My problem is that I have to implement the f function with a 8-1 multiplexer.
For numbers 0 and 1, the f0 value is the same as D0, for 2 and 3 f0 is the same as D0' etc. for the last number, 12, f0=1. But shouldn't I somehow have the values for a total of 16 numbers? Can I treat the rest of the numbers (that I'm not interested in as don't care conditions? If so, how could this be implemented in a multiplexer?
Any help would be greatly appreciated!!!

Last edited: Dec 16, 2011

Nov 25, 2009
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3. ### ambageo Thread Starter New Member

Dec 16, 2011
4
0
ok,thank you very much!!!