Half adder/Full adder circuit

Discussion in 'Homework Help' started by iamminn, Dec 10, 2012.

  1. iamminn

    Thread Starter New Member

    Dec 10, 2012
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    0
    /* Question
    Attached is a circuit of half adders and full adders.

    Given:
    A = 101 base2
    B = 011 base2

    Find the 5 bit output of this circuit.
    */

    I have gotten an output of -> 10100 base2

    On the diagram i have placed 1's and 0's to illustrate how i worked this out on my worksheet.

    Is my answer and work completely off?
     
  2. JohnInTX

    Moderator

    Jun 26, 2012
    2,347
    1,029
    First of all 5 + 3 = 8 so your result should be 01000. A simple test.

    Your inputs are incorrect to the adder sections. Each section should add
    Ax + Bx where x is the same power of 2 i.e. the binary column.

    Then:
    HA does A0+B0 =X0 with Cy0out to the next section (the FA) then
    FA does A1+B1+Cy0 = X1 with Cy1 out etc. moving from right to left as you have it drawn.
     
  3. iamminn

    Thread Starter New Member

    Dec 10, 2012
    6
    0
    This is not a normal addition circuit though so wouldn't that test be irrelevant?

    Also I can assure you the Input to the adders is set up correctly. It is how our professor has set the circuit up. The first HA's inputs should be Bsub1/Bsub0 and so on.

    Thanks for your input!
     
  4. JohnInTX

    Moderator

    Jun 26, 2012
    2,347
    1,029
    Yup. I misunderstood what you were doing.

    As wired, it looks like the logic is OK.
     
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