Implement a full adder for two 2 bit binary numbers by using (4:1) multiplexer

beenthere

Joined Apr 20, 2004
15,819
Make a truth table for the various combinations of the bits. Arrange the multiplexer to select an output based on the truth table.
 

beenthere

Joined Apr 20, 2004
15,819
Look at the data sheet for a multiplexer like a 74153. See what it takes to select the input that gets connected to the output. Should be pretty obvious from there.
 

beenthere

Joined Apr 20, 2004
15,819
Write the data sheet? It's already been done - www.[B]datasheet[/B]catalog.com/datasheets_pdf/7/4/1/5/74153.shtml - 15k.

If you are referring to the truth table for a two bit ADD, surely you can work that out?
 

Mithryll

Joined Nov 22, 2008
6
not so detailed we saw.. question just wants the implement a full adder for two 2-bit binary numbers by using 4:1 multiplexer modules. and it says don't use additional gates.
 

beenthere

Joined Apr 20, 2004
15,819
Use each pair of bits to address a multiplexer. insure the inputs are arranged such that the output agrees with the truth table.
 

Mithryll

Joined Nov 22, 2008
6
is this a true truth table?

A1 A0 B1 B0 | S1 S2 C1 C2
--------------------------
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0
0 | 0 | 0 | 1 | 1 | 0 | 0 | 0
0 | 0 | 1 | 0 | 0 | 1 | 0 | 0
 

beenthere

Joined Apr 20, 2004
15,819
It is a fraction of one. Make the full truth table with the carries included, and you will be able to tell how many multiplexers will be needed.

Yes, I'm being a bit dense, but it is your assignment. You really need to do some thinking on your own instead of leaning on us.
 
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