Need help with a sequential circuit

Discussion in 'Homework Help' started by kainotk, Mar 10, 2013.

  1. kainotk

    Thread Starter Member

    Mar 31, 2009
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  2. kainotk

    Thread Starter Member

    Mar 31, 2009
    10
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  3. panic mode

    Senior Member

    Oct 10, 2011
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    two inputs marked X are not a problem (just tie them together, this is common representation). two outputs marked Y is clearly an error. they should be Y1 and Y2.

    one of them is combinational output, other is sequential.

    the only time where two active outputs (not tristate) can be tied together is when using wired AND (requires open drain/collector output). if this circuit is part of the question, then such output design must be clearly mentioned.
     
  4. kainotk

    Thread Starter Member

    Mar 31, 2009
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    Thank you.

    The second part of my question is with the sequential part of the circuit.

    It's clear at the output y (from the 3-input OR) that a x' will cause y = 1 (a "0" is detected), then what is the purpose of the sequential part of the circuit?
     
  5. WBahn

    Moderator

    Mar 31, 2012
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    It looks to me like this is a deliberately convolute circuit that does the same thing that a much simpler circuit could do.

    If you track through the states (and assuming I did it correctly) then you will discover that the output is a 1 if either the present input is 1 or if the input was 1 at the previous rising clock edge. So it's not quite the same as just an inverter, but it is very close to it.
     
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