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How to construct XOR function using NORs?

Discussion in 'Electronic Basics' started by Rakesh Sharma, Sep 26, 2004.

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  1. Hi,

    How would I construct an XOR function using NOR gates ONLY? I have
    tried breaking my head over it but haven't come up with a solution.

    Thanks in advance

  2. Ian Stirling

    Ian Stirling Guest

    Work out how to make other stuff.
    Start out with an inverter.
    Now, see if you can use this to make an and gate.

    Now, go on to nand and ...

    Now, you have the building blocks.
    Start playing with them, and see how you can reduce the gate count
    as much as possible.
  3. Fred Bloggs

    Fred Bloggs Guest

    EXOR(A,B)=OR(AND(A,/B),AND(/A,B)) and since AND(X,Y)=NOR(/X,/Y) and
    OR(X,Y)=NOT NOR(X,Y) you're done.
  4. --------------------
    These files comprise a complete course in Boolean transformations.
    If you study them you can do anything.
    files: boolean & boolean2 and demorgan & demorgan2 -> .txt

    and add an inverter to the output.


  5. This should work:

    | |1 |o-------.
    | .-|__| |
    | __ | | __ __
    A----o-|>=| | '-|>=| .------|>=|
    |1 |o----| |1 |o-' |1 |o- X
    B----o-|__| | .-|__| .---|__|
    | | __ | |
    | '-|>=| | |
    | |1 |o-------' 0|
    created by Andy´s ASCII-Circuit v1.24.140803 Beta

    Must be viewed in fixed font.
  6. Rich Grise

    Rich Grise Guest

    Please don't do the kiddies' homework for them.

  7. I've deliberately taken out the cross-posting.

    You do realize that this sort of question is in all kinds of books. If
    you don't have a source to look it up, you do lack a basic library that
    everyone interested in electronics should have.

    One could go to the public library if one's stuck for lack of books.

    Likely a search of websites will turn it up.

    Finally, the only real reason you would want to do this is for homework.
    It's much simpler to get an exclusive-or gate than wire up other gates.
  8. Tim Wescott

    Tim Wescott Guest

    The last two months of Embedded Systems Programming
    ( has a nice column on Karnaugh maps and the
    Quien-McClusky method -- look for Jack Crenshaw's math column.
  9. Andyb

    Andyb Guest

    Why's everyone got such a downer on helping kids with homework? Sure, don't
    do it for them, but a prod in the right direction is reasonable.

    In my day <dons slippers><lights pipe> we'd have got extra marks for knowing
    where to look for help on the Internet!

  10. Witt

    Witt Guest

    All of the propositional functions can be expressed in terms of 'nor',
    (or in terms of 'nand')

    If 'nor' is primitive:

    1. not(p) =df (p nor p)
    2. (p or q) =df not(p nor q)
    3. (p and q) =df not(not(p) or not(q))
    4. (p nand q) =df not(p and q)
    5. (p only if q) =df (not(p) or q)
    6. (p if q) =df (p or not(q))
    7. (p if and only if q) =df (p if q) and (p only if q)
    8. (p xor q) =df not(p if and only if q).

    1a. ~p <-> (p nor p)
    2a. (p v q) <-> ~(p nor q)
    3a. (p & q) <-> ~(~p v ~q)
    4a. (p nand q) <-> ~(p & q)
    5a. (p -> q) <-> (~p v q)
    6a. (p <- q) <-> (p v ~q)
    7a. (p <-> q) <-> ((p <- q) & (p -> q))
    8a. (p xor q) <-> ~(p <-> q).

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