2 bit comparator-adder-subtractor with two values

Discussion in 'The Projects Forum' started by 74266, Mar 20, 2016.

  1. 74266

    Thread Starter Member

    Mar 20, 2016
    41
    0
    Hello everyone I would like to ask if someone know how to make a 2 bit comparator-adder-subtractor with two values
    for this project there must be 4 seven segment 1 is for the command which is comparator-adder- subtractor, 2 is for the two values,and the last is for the result.
    Next for the display of the command 0 is for NOP(no operation),1 is for compare,2 is for add,3 is for subtract. The display values is only up to 0-3. And the final result value is only up to -3 to 6. I know the basic of adder,subtractor,comparator and seven segment its just this kind of project is kinda to complicate for me right now that why I would like to ask for help for this .Also for negative you will use dot(h)

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  2. absf

    Senior Member

    Dec 29, 2010
    1,493
    372
    First you'd need a 74HC139 for decoding the 2 bit instruction to 4 action lines for the compare, add & sub logic...

    Is this home work of some kind? When is the dead line?

    Allen
     
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  3. 74266

    Thread Starter Member

    Mar 20, 2016
    41
    0
    Our project requirements must only use basic gates which is 7408(AND), 7404(NOT), 7432(OR),7486(XOR),74266(XNOR),7400(NAND) and 7402(NOR)
    OUR project deadline will be tomorrow so It would be nice to finish before the afternoon tomorrow here
     
  4. absf

    Senior Member

    Dec 29, 2010
    1,493
    372
    OK, then do you know how t0 make a 2_to_4 decoder using the gates that you mentioned?

    See page 1 of the datasheet attached. You dont need the enable function of the chip. So to make the 2 to 4 decoder, you need a 7400 and a 7404 (4/6) chips.

    Allen
     
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