multiplexer implementation

Discussion in 'Homework Help' started by Xufyan, May 30, 2011.

  1. Xufyan

    Thread Starter Member

    Aug 3, 2010
    114
    0
    I had a question to implement this equation through multiplexers,
    f(x,y,z) = Em (1,2,6,7) but the condition is,
    only x and y be the selection line,

    [​IMG]

    see the above picture of my truth table, the 3 data line selector multiplexer is reduced to 2 data lime selector multiplexer , but i am confused how to draw its circuit ? because 'z' is now an input.
    how to implement 'z' ??
     
    Last edited: May 30, 2011
  2. Georacer

    Moderator

    Nov 25, 2009
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    1,266
    You are allowed to use an inverter (NOT gate) to complement the input 'z' and drive it into the MUX. That said, your circuit will be comprised from a 4-to-1 MUX and a NOT gate.
     
  3. Xufyan

    Thread Starter Member

    Aug 3, 2010
    114
    0

    is it so ?
    [​IMG]
     
  4. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    Oh, now I see what your problem is.

    The Multiplexer is a ready-made IC. You don't have to build it yourself from simpler gates, like you did in post #3. For example, the one you want could very well be this one:
    http://www.datasheetcatalog.org/datasheets/134/231447_DS.pdf
    You can use it in a schematic just like you drew it in your first post.

    The NOT gate I was talking about was the one you have to use to invert the z signal and drive it into the D1 pin of the MUX.
     
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