Past Paper Qs.

Discussion in 'Homework Help' started by kota, Apr 14, 2011.

  1. kota

    Thread Starter New Member

    Apr 14, 2011
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    Question: Using Kmaps, design an arithmetic and logic unit that can perform functions of three 1-bit variables X, Y, Z as shown
    M1 M2 FUNCTION RESULT COMMENT
    0 0 ADD X+Y+Z + is arithmetic add
    0 1 Subtract X-Y-Z - is aritmetic subtract
    1 0 AND X.Y.Z . is boolean AND
    1 1 OR X+Y+Z + is boolean OR

    My guess at this question is as follows,
    5 input, so a 5 variable Kmap.

    What i dont get is, for the arithmetic part, do I need a separate LED to show carry/borrow occurred? And when I'm doing out the state table, is this how I should go about it

    X Y Z | M1 M2| Present Output
    0 0 0 | 0 0 | 0
    | 0 1 | 0
    | 1 0 | 0
    | 1 1 | 0
    0 0 1 | 0 0 | 1

    .... and so on. It seems a bit long winded?
    Thanks for any help and comments. I hope I've gotten at least one part right. Even if it is only the question taken down right.
     
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