circuit design help

Discussion in 'Homework Help' started by zaidsh, Apr 20, 2015.

  1. zaidsh

    Thread Starter New Member

    Apr 20, 2015
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    I need a help on several points in my design, well the design is like this :

    1.(input two numbers) *2

    2.
    if c = 0 ---> input1 + input2
    if c = 1 ---> input1 - input2

    3. output the bigger number of the two inputs.

    please someone help me because this subject is really hard for me and i'll lose my scholarship if I get low grades on this subject! if you don't want to do the whole design just tell me what should I do I'll lookup the steps, thanks!
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    I am missing the design part.
     
  3. zaidsh

    Thread Starter New Member

    Apr 20, 2015
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    that's the problem I don't know how to start it...
     
  4. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    You can start with better description of the assignment.
     
  5. WBahn

    Moderator

    Mar 31, 2012
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    What kind of circuit are you supposed to be designing? Where do these inputs come from? How is the output handled? What is this parameter 'c' and where does it come from?
     
  6. zaidsh

    Thread Starter New Member

    Apr 20, 2015
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    I'm using a software called logisim, You input two numbers (A1A0, B1B0) using pins, and another pin called C , if C = 0 then its A1A0 + B1B0, if C= 1 then its A1A0 - B1B0, and then when we get the result we multiply it by two, and the circuit should also determine the bigger number (A1A0 OR B1B0).

    I'm guessing adders and subtractors and comarators, yet I don't know what else to use OR how to effeciently use them.

    I hope I was able to answer your questions .
     
  7. WBahn

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    Mar 31, 2012
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    So how could you use a 2-bit full adder to implement subtraction in response to a control signal?

    If you have a subtractor, how can you determine which of two numbers is bigger?
     
  8. zaidsh

    Thread Starter New Member

    Apr 20, 2015
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    I cant answer the first one but the 2nd I'd say before we do the arithmatic operation we compare
     
  9. WBahn

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    Mar 31, 2012
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    So how do you do the compare?

    If I have two numbers, A and B, there is an arithmetic operation that I can perform that will trivially allow me to state, based on the result of that operation, whether A>B, A<B, or A=B. What operation is that?
     
    Alec_t likes this.
  10. zaidsh

    Thread Starter New Member

    Apr 20, 2015
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    using the comparator?
     
  11. WBahn

    Moderator

    Mar 31, 2012
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    A comparator is not an arithmetic operation. Think addition, subtraction, multiplication, and division.
     
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