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Homework Help: Need some help with a synchronous circuit

  1. Sep 28, 2010 #1
    I'm trying to analyze the following circuit which is pretty basic.
    There is the circuit and it's diagram which is the solution:

    http://img822.imageshack.us/img822/7291/circuiti.jpg [Broken]

    Please help me find the mistake, because my diagram becomes different from the one in the picture.

    Looking at the circuit, I see that:
    T1=Co=A*B +A*Cin +B*Cin=Q1*Q1 +Q1*X +Q2*X
    T2=S=A XOR B XOR Cin = Q1 XOR Q2 XOR X

    and then i get a small table to organize everything:

    Code (Text):
    present   next
    state      state
                x=0         x=1
    Q0 Q1   T1 T2 Z    | T1 T2 Z
    0 0     0  0   0    0   1  0
    0 1     0  1   0    1   0  0
    1 0     0  1   0    1   0  0
    1 1     1  0   0    1   1  1
    and obviously if i draw the diagram it looks much different from the one I'm supposed to get.

    Can anyone tell me where did I go wrong?
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Sep 28, 2010 #2


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    I agree with you. I think the diagram is wrong.
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