Full adder

Discussion in 'Homework Help' started by rds1975, Aug 30, 2004.

  1. rds1975

    Thread Starter New Member

    Aug 30, 2004
    8
    0
    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
     
  2. Mjollnir

    Member

    Apr 22, 2004
    27
    0
    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
     
  3. recca02

    Senior Member

    Apr 2, 2007
    1,211
    0
    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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