Thread: ChipAte Emulation

  1. #1
    i dont know Vicious's Avatar
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    ChipAte Emulation

    I am writing my first wmulator and since there arent many good tutorials out there... I want to make sure Im on the right track.

    My first question...

    Is this the proper way of emulatiing the CPU?

    Code:
    void CpuEmulation()
    {
      OpCode = (Memory[PC] << 8) + Memory[PC + 1];
    
      switch(OpCode&0xF000)
      {
        case 0x0000:
          if(OpCode&0x00F0 == 0xE)
            ClearScreen();
          PC+=2;
        break;
    
        case 0x1000:
          MemoryPosition = OpCode&0x0FFF;
          PC+=2;
        break;
    
        case 0x3000:
          if(V[OpCode&0x0F00] == OpCode&0x00FF) PC += 4;
          else PC += 2;
        break;
    
        case 0x5000:
          if(V[OpCode&0x0F00] == OpCode&0x00F0) PC += 4;
          else PC += 2;
        break;
    
        case 0x6000:
          V[OpCode&0x0F00] = OpCode&0x00FF;
          PC+=2;
        break;
    
        case 0x7000:
          V[OpCode&0x0F00] += OpCode&0x00FF;
          PC+=2;
        break;
    
        case 0x8000:
          if(OpCode&0x000F == 0)
            V[OpCode&0x0F00] = V[OpCode&0x00F0];
          PC+=2;
        break;
    
        case 0xB000:
          MemoryPosition = OpCode&0x0FFF + V[0];
          PC+=2;
        break;
      }
    }

  2. #2
    ATH0 quzah's Avatar
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    You mean other than the fact that you're using globals everywhere?

    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
    i dont know Vicious's Avatar
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    oh..

    I take it, thats a bad thing....

    Look, this is the first time ive tried to program anything other than a game. I am just trying to figure out if Im doing this the right way, or if there is a better way. I was thinking I might have to shift some more bits or something

    I am going to attach my source code and see if any one can give me some pointers. Not to tell me how stupid I am for doing something, just to kindly give me advice.

  4. #4
    .
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    Working from a decnet set of examples might be a good thing to try.

    http://koti.mbnet.fi/~atjs/mc6809/
    Last edited by jim mcnamara; 06-29-2004 at 02:58 PM.

  5. #5
    ---
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    whether you are close to writing it correctly or not its still a damn good attempt.
    im sure i saw a whole lot of emulator dev tutorials somewhere...

  6. #6
    i dont know Vicious's Avatar
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    Why Thank You!

    I have managed to load a rom and it actually draws a few thing on the screen. I found a really good explanation of all the Instructions of the chip8, but I cant figure out how to implement the 'I' address register...

  7. #7
    Registered User Codeplug's Avatar
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    Out of curiosity, I looked up chip-8 and found alot of info on this forum.

    gg

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