how to implement a certain comparator using PROM..

Discussion in 'Homework Help' started by transgalactic, May 4, 2008.

  1. transgalactic

    Thread Starter Active Member

    Apr 29, 2008
    74
    0
    the circuit compares two numbers each number has 3 bits
    where Y >=3 and X <=5
    it has one output if X>Y then g=1 if X<Y then G=0
    if X=Y then G= dont care

    i need to implement using 2^2X1 and 2^2X4 PROM's

    i cant think of a way to combine them
    ????
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Make a table using the numbers. In each case, the output will be less than, equal, or greater than. Program the PROM using the numbers as the address. Each address should output the correct comparison.

    Please stay with one thread instead of opening a new one on the same subject.
     
  3. transgalactic

    Thread Starter Active Member

    Apr 29, 2008
    74
    0
    i know how to create a truth table
    i dont know how to split it into the programing tables using these kind of prom's

    ???
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Truth table was not a good term. More like a state table. Call one value X and the other Y.

    For all X = Y, the EQUAL output is true.
    For all X < Y, the LESS THAN output is true
    For all X > Y, the GREATER THAN output is true.

    Choose some value for the PROM to output for the three conditions, Using the values as addresses, program the PROM so the output expresses the comparison of the X bits to the Y bits.
     
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