Help Please!

Discussion in 'Homework Help' started by minimugy, Mar 23, 2011.

  1. minimugy

    Thread Starter New Member

    Mar 2, 2011
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    Hello!

    i've been give a problem that i am stuck on. if you can help that'd be great!

    Write an equation for the following sequences (use only three variables for the right hand side): The overflow indicator V will turn off iff X is negative, Y is positive, and D is positive, or Xis positive, Y is negative, and D is negative.

    so far i have,

    V=X'YD + XY'D'

    i was thinking it would be an exclusive or but i was told that was wrong, so if you can help me simplify this it would i would really appreciate it.

    Thanks in advance!!
     
  2. mjhilger

    Member

    Feb 28, 2011
    119
    16
    Have you written your truth table or karnaugh map? That would be a great place to start. Once you have that, you should be able to see how to write your equation.
     
  3. minimugy

    Thread Starter New Member

    Mar 2, 2011
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    0
    I did but it gave me the same function i have above. so thats where i am stuck.

    would it be wither one of the two since the two products are the exact opposite of each other?
     
  4. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    When V is off, is it true or false?
     
  5. minimugy

    Thread Starter New Member

    Mar 2, 2011
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    I believe it is off if either of the two hit. but i need to get it to only 3 terms on the right side and i have six.
     
  6. mjhilger

    Member

    Feb 28, 2011
    119
    16
    Your statement says that V will turn OFF iff .....

    So your equ should be:
    V' = X'YD + XY'D' <- is three variables X, Y, D

    Or are you saying that you may only use X or X' (etc.) but not both? Not sure what you are looking for?

    You cannot use XOR of 3 variables, because it would give 3 states for V', not just the 2 you are looking for.
     
  7. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Your original statement didn't say "3 terms", it said "3 variables".
     
  8. minimugy

    Thread Starter New Member

    Mar 2, 2011
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    well i re read the wuestion and it says 3 variable which i guess iw as confused with 3 terms or something. i felt like it only needed to be either X'YD or XY'D' to v but now i see that i only have 3 variables and i was done all along. I'm sorry about my confusion and any confusion i may have cause you. Thanks for the help!!!!
     
  9. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    I was going to make the same point, but I am wondering why the stipulation "use only three variables for the right hand side", since there are only 3 variables available. How could you possibly use more?
     
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