Two 4-bit Binary Adder using SPDT switches and only 1 Full Adder Circuit

Discussion in 'Homework Help' started by arwayeyen, Mar 1, 2012.

  1. arwayeyen

    Thread Starter New Member

    Mar 1, 2012
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    Title says it all. I need help in designing a circuit that has two 4-bit binary adder using SPDT switches. The catch is to make this with just 1 Full Adder circuit. If anyone could please help me out with this one along with a diagram, that would be great. :)
     
  2. Georacer

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    Nov 25, 2009
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    I imagine this is homework. I moved it to the right place.

    Can you elaborate a bit more?

    Must the two results calculate simultaneously?
    How many bits does the full adder have?

    A full question repost would be helpful.
     
  3. Kn0x_14

    New Member

    Mar 2, 2012
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    we also have the same problem
    input:two 4 bit binary numbers implemented by SPDT switches
    output: Sum shown through LEDs
    the circuit must contain only one full adder
    please help us...
    thanks...
     
  4. Georacer

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    Nov 25, 2009
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    I imagine you want the following:

    Use a 1-bit full adder in a sequential circuit to process the input digits step by step. You will need 4 cycles to process the whole input and some kind of storage, ie shift register.

    But I don't see how it can be done with *only* one full adder.

    As I said, repost the original homework question.
     
  5. Kn0x_14

    New Member

    Mar 2, 2012
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    4-bit Binary Adder

    Input: 2 4-bit binary numbers implemented by SPDT switches
    Output: Sum shown through LEDs

    Your circuit must add two binary numbers correctly. You may add additional control if you wish to.

    Note: Your circuit must contain only ONE (1) Full-Adder circuit and provide me a schematic diagram.


    NOTE:

    You will use a single (ONE) FULL-ADDER Circuit

    Any Implementation of a Full-Adder is still a full-adder.
     
  6. Georacer

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    Nov 25, 2009
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    Ok, this is a bit fuzzy. What is the context of your course at the moment? Are you still at the basic logic functions (addition, Boolean algebra) or have you reached sequential circuits?

    I 'd like to interpret the lack of a bit width specification for the full adder as you being able to use a 4-bit adder, like the 7483 IC.

    On the other hand, when referring to a full adder, we usually mean a 1-bit unit. But with only one 1-bit unit, this 4-bit operation is impossible.

    So what I suggest: Use a 4-bit full adder to add your two addendums. At the same time ask for a clarification from your professor. Badly expressed exercises aren't that uncommon.
     
  7. Kn0x_14

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    Mar 2, 2012
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    yes we're already studying sequencial logic
     
  8. Georacer

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    Nov 25, 2009
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    Ok. Then could it be that your professor wants to use a 1-bit Full Adder, which you will use to add the two input numbers one bit pair at a time?

    That calls for two shift registers as input buffers and a shift register for the output storage.

    Consider this option, but keep in mind that it call for three additional ICs, plus another to provide D-Flip Flops to create a functional pipeline.
     
  9. Kn0x_14

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    Mar 2, 2012
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    can you please provide me a schematic diagram for that problem? because we have to submit our circuit tomorrow if it is possible.tnx
     
  10. bertus

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  11. Georacer

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  12. bertus

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  13. Kn0x_14

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    Mar 2, 2012
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    sir Geo and sir Bert thank you for all your advice it helps me a lot...
     
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