logicboolean-logic

Implementing 5-variable function using multiplexers


If I have a 5-variable function (below) and I want to implement it using a multiplexer, how would I do that (using the minimum possible multiplexer):

f(A,B,C,D,E) = A + C'D + BD' + B'D + B'CE

This is homework, so don't provide a solution, just a guidance of how that works.

Thanks!


Solution

  • 5 variables means a 2**5 (32) input multiplexer, with inputs 0 through 31. Convert the terms into binary numbers and hold the corresponding inputs high. For B'CE we have:

    A B C D E
    X 0 1 X 1
    

    This gives us 4 numbers, since we have 2 don't cares. The four numbers are:

    00101 = 5
    00111 = 7
    10101 = 21
    10111 = 23
    

    Hold inputs 5, 7, 21, and 23 high.

    Repeat for the rest of the terms.