8 bit TTL microprocessor design

Discussion in 'The Projects Forum' started by CENG, Jun 12, 2012.

  1. CENG

    Thread Starter New Member

    Jun 12, 2012
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  2. panic mode

    Senior Member

    Oct 10, 2011
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  3. CENG

    Thread Starter New Member

    Jun 12, 2012
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    Thanks. How to expand it to 8 bits design?
     
  4. crutschow

    Expert

    Mar 14, 2008
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    The circuit reference you posted is for a 4/8 bit design. It can be used to build either.
     
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  5. panic mode

    Senior Member

    Oct 10, 2011
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    step 1. print the diagram
    step 2. get a red pen
    step 3. cross every "4" on the diagram
    step 4. write "8" next to every "4" that was crossed
    step 5. think what would take to make that 16-bit design
     
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  6. CENG

    Thread Starter New Member

    Jun 12, 2012
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    How exactly can I build 8 bit microprocessor from the schematic? Double the ALU? I'm not sure as there are already two 74LS181 there.
     
  7. crutschow

    Expert

    Mar 14, 2008
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    Since a 74LS181 is a 4-bit ALU then two of them will handle 8 bits. You don't need to add any more.
     
  8. CENG

    Thread Starter New Member

    Jun 12, 2012
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    My project is to build an 8 bit microprocessor, not a 16 bit.
     
  9. CENG

    Thread Starter New Member

    Jun 12, 2012
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    Thanks. Can you help me in details to expand the design to 8bit? I need to get it done in three weeks...
     
  10. crutschow

    Expert

    Mar 14, 2008
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    The reference in your first post has a schematic diagram of the circuit. What more detail could you need? :confused:
     
  11. dataman19

    Member

    Dec 26, 2009
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    Do I smell a Rodney Robot Design?
    ..
    Dave
    Phoenix, AZ
     
  12. CENG

    Thread Starter New Member

    Jun 12, 2012
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    Nope. This is the fundamental requirements of my project:
    Project Title: 8-bit Microprocessor Emulator
    Proposed Tools: TTL logic chips, Microcontroller
    Project Outcome
    1. A discrete hardware emulator of a simple 8-bit CISC microprocessor using TTL logic chips.
    2. Able to run a subset of assembly code compiled on a PC and downloaded to the emulator.
    3. Able to display the data on the data-path of the processor.
     
  13. Sparky49

    Active Member

    Jul 16, 2011
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    This does have an 8 bit address, but only a 4 bit instruction length.

    Is this what you want as 8 bit?

    P.S. I don't want to seem rude, but as this is your project, shouldn't you be designing it yourself? I don't know how unis work - are you allowed to copy circuits?
     
  14. takao21203

    Distinguished Member

    Apr 28, 2012
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    Do you know how "message in space" works?

    You can use this as starting point for a microprocessor.

    For message in space, the PC always increments by one.
    For microprocessor, you need to change this, add branching.

    However it's a lot of effort actually even only to build message in space using TTL only. I have done this a while ago, but it was so much effort to wire, it was scrapped.

    3 weeks for TTL microprocessor? Seriously?

    I would use WINCUPL eventually to simulate the logic, and use message in space principle as a starting point.

    If you are allowed to use small microcontrollers, things get easier but you need to be good at using these.

    On a public forum you can get some hints to help you shortcut, to get a starting point, but it's far too much and far too complex.

    And simply using a ready-made schematic is bad for this.

    Really try to build message in space using WINCUPL etc., and see if you can add branching as well.

    The ring counter address pointer (or register) for the message data is changed, to become PC (program counter)!
     
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  15. Sparky49

    Active Member

    Jul 16, 2011
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    To give you an idea of time, I'm following the progress of someone who is making a computer out DTL. It has been over three months, and he says he's only 1/20th through the project.
     
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