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Homework Help: Boolean algebra problem

  1. Sep 23, 2005 #1
    Boolean algebra problem!!

    Hello everyone 'im designing a IC that will tell output a 1 if the number is > 9. so I wrote this boolean expression but i'm stuck on reducing it.
    B' = B compelemnted
    AB'CD' + AB'CD + ABC'D' + ABC'D + ABCD' + ABCD
    AB'(CD' + CD) + AB(C'D' + C'D + CD' + CD)
    any hints? thanks!
  2. jcsd
  3. Sep 23, 2005 #2

    If my karnaugh map is not rusty, i got

    AB + AC
  4. Sep 23, 2005 #3
    *ab'cd' + Ab'cd + Abc'd' + Abc'd + Abcd' + Abcd
    *ab'c(d'+d) +abc'(d'+d) + Abc(d'+d)-----> (d+d') =>1
    *ab'c + Abc' + Abc
    *a(b'c+bc') +abc
    *a[b Xor C + Bc]
  5. Sep 23, 2005 #4
    The answer that 'waht' got is the correct one (a mapping easily shows that). I don't think though that I should do the actual Boolean equation for you, but I'll give you a couple of hints. Group as many of the "AND" terms together with (X + X') terms, to eliminate as much as you can to start. Then remember that you can take something like: "XYZ +........." and make it "XYZ + XYZ + ......". In other words, writing a term twice in an equation doesn't change anything. It can make it easier to work out. If you try these, you should get the answer to your original equation. Then let us see it and we'll check it for you.

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