Full adder

Thread Starter

rds1975

Joined Aug 30, 2004
8
Hi all

Request some help in giving some hints to start with :

A one-bit full adder is to be implemented using 8-to-1 multiplexers
(a) Write the t ruth table for sum (S) and carry to the next stage CN in terms of
the two bit (A, B) and carry from the previous stage (CP) . The t ruth table
should be in the ascending order of (A,B,CP).

(B) Implement S and CN using 8-to-1 multiplexer.

Thanks and regards
 

Mjollnir

Joined Apr 22, 2004
27
Well the truth table is the easy part


A B C-P Sum C-N
0 0 0 0 0
0 0 1 1 0
0 1 0 1 0
0 1 1 0 1
1 0 0 1 0
1 0 1 0 1
1 1 0 0 1
1 1 1 1 1
 

recca02

Joined Apr 2, 2007
1,214
well calm down chirag,
and avoid using such offensive language,
that language is for illiterates not deprived of education but common sense.
the above ckt can easily be made using 4:1 mux,
however i think two mux wud be req in any case ,one for carry and other for sum,
the ckt is very simple,
observe for what i/p the sum or carry o/p is high and for what low.
based on these i/p apply logic 1 or logic 0 at i/p of respective data lines.

example:
for sum:
d0,d3,d5,d6
wud be given logic 1,
while
d1,d2,d4,d7
wud be given logic 0.
now a,b,cp
are inputs to selection lines for mux taken in order.
same method wud apply for c n o/p.
 
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