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Homework Help: Is it Possible to Solve This Problem - Equations and Building Circuits

  1. Mar 3, 2013 #1
    # -> means XOR
    ' => means NOT
    AB => means A and B
    A+B => means A or B

    Is it possible to build the following 3 functions

    Using only 4 chips (Build all three functions using only 4 chips not 4 for each function)

    I have 8 switches for the inputs and was going to use
    Switch 1 for A
    Switch 2 for B
    Switch 3 for C
    Switch 4 for D
    Switch 5 for A'
    Switch 6 for B'
    Switch 7 for C'
    Switch 8 for D'

    I don't have any other switches. I'm just using a switch and flipping switch 8 to the opposite of switch 4 to get the NOT of D.

    I can only use the following chips. At the end of the day there can only be 4 chips on my protoboard so if I use the same chip say twice than this counts as two chips.

    7400, 7402, 7404, 7408, 7410, 7411, 7420, 7421, 7425, 7427,
    7432, and 7486.

    I'm getting that it's not possible and have spent several hours trying to do it. Thanks for any help that you can provide me!
  2. jcsd
  3. Mar 3, 2013 #2


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    Staff: Mentor

    What is the closest that you've gotten? Can you post what you have tried?
  4. Mar 4, 2013 #3


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    Staff: Mentor

    Normally you would use a switch to provide D, and use a gate to generate D'.
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