2-to-1 and 4-to-1 Multiplexer

Discussion in 'Homework Help' started by 123456, Aug 2, 2006.

  1. 123456

    Thread Starter New Member

    Jul 24, 2006
    8
    0
    i'm sorry to borrow yr thread.
    but i seriously need the truth-table of a 2-to-1 multiplexer & a 4-to-1 multiplexer.

    let's say for 2-to-1,
    S1, I0, I1

    4-to-1,
    S1, S2, I0, I1, I2, I3

    many thanks.
     
  2. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    143
    Please do not hijack another users thread.

    Take the 2-to-1 multiplexer as an example: you require there to be a control signal, C0, in addition to the above signals you describe.

    If C0 = 0 then the output S1 will follow input 1, I0 and input 2, I1 is a don't care, i.e. it has no influence on the output.

    If C0 = 1 then the output S1 will follow input 2, I1 and input 1, I0 is a don't care.

    Hence the truth-table goes:

    CO I0 I1 S1
    0--0--0--0
    0--0--1--0
    0--1--0--1
    0--1--1--1
    1--0--0--0
    1--0--1--1
    1--1--0--0
    1--1--1--1

    The same logical arguement applies to the 4-to1 multiplexer, however there are two control signals, C0 and C1.

    Dave
     
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