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Thread: PC-Engine

  1. #111
    EmuTalk Member malducci's Avatar
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    Quote Originally Posted by Aladar View Post
    Yes, for now my emulator simply adds a cycle, but during the tests, for correct results,
    I have also considered possible wait states introduced by the register VRR/VWR.
    .
    That's going to be a bit tricky if you emulate /BUSY of the VDC. It's fractional of a single cpu cycle and can be even less than a single cpu master clock (21mhz).



    Edit:

    Doing an approximation would probably be fine. I know of two instances where /BUSY can really effect VRAM read/writes - stalling the cpu for *many* cpu cycles.
    Last edited by malducci; December 19th, 2008 at 20:34.

  2. #112
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    Not only many cycles, modifying the display registers with unusual values and
    trying to access the VRAM is also possible to definitely stop the cpu!
    The target of my emulator is the perfect reproduction,
    for this reason I am not interested in approximate solutions.
    Ambitious, I know, but to write another emulator with only enough accuracy for
    games and demos doesn't have sense.

  3. #113
    EmuTalk Member malducci's Avatar
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    Quote Originally Posted by Aladar View Post
    Not only many cycles, modifying the display registers with unusual values and
    trying to access the VRAM is also possible to definitely stop the cpu!
    Yeah. A set of registers sets the VRAM 'speed' in that you get less and less 'cpu' slots per 8pixel dot clock. The lowest setting results in no cpu slots during active display and pauses the processor till the end of the star to of the next scanline. But I was referring to normal VRAM speed settings and normal VDC register settings. There are certain points in the frame where the VDC provides no 'cpu' slots to vram. And of course the length of the stall is variably based on some conditions.

    The target of my emulator is the perfect reproduction,
    for this reason I am not interested in approximate solutions.
    Ambitious, I know, but to write another emulator with only enough accuracy for
    games and demos doesn't have sense.
    Look forward to seeing you're findings

  4. #114
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    Ambitious, I know, but to write another emulator with only enough accuracy for
    games and demos doesn't have sense.
    Personally, I think there is. People could code emu's for just lulz Or to improve thier programming skills. It doesn't have to be all about documenting hardware to the per-cycle level imo.

  5. #115
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    mudlord88, I agree with you! I was speaking of myself...

  6. #116
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    PicchioEngine v0.0.2 (2009/01/23)
    - The system now run at exactly 21477272+(8/11)Hz.
    - Implemented the linear phase low-pass filter using the BLEP synthesis.
    This filter is used to reduce the sampling rate from 3579545+(5/11)Hz to 48kHz.
    - Emulated accurately the RC audio filters present on the DUO-R.
    - Added a preliminary and incomplete PSG emulation.

  7. #117
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    PicchioEngine v0.0.2 (2009/01/23)
    - The system now run at exactly 21477272+(8/11)Hz.
    - Implemented the linear phase low-pass filter using the BLEP synthesis.
    This filter is used to reduce the sampling rate from 3579545+(5/11)Hz to 48kHz.
    - Emulated accurately the RC audio filters present on the DUO-R.
    - Added a preliminary and incomplete PSG emulation.
    Congrats! . Have you got any games/demos/tests displaying anything? (I know VDC in incomplete but still...)

  8. #118
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    Thanks AamirM!
    Suggestions:
    - My emulator doesn't support zip files, only uncompressed rom images.
    - If present, remove the header(512byte) from the file.
    - For the US games with the regional protection, in the file 'IOPort.cpp' replace
    the line 'return (Joypad::read() | 0xF0);' with 'return (Joypad::read() | 0xB0);'.
    Last edited by Aladar; January 24th, 2009 at 14:13.

  9. #119
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    I did all that already. I think the games I tried to run depended on some unimplemented VDC feature. Can you name a games (with sound) which runs? I just want to hear the sound .

  10. #120
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    Try Magical Chase, it is not playable but seems to work in demo mode,
    in this way you can listen some music.

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