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Thread: running galaxy mod player on cga

  1. #1
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    Default running galaxy mod player on cga

    Ok, i have galaxy player running on a 286 anda cga (original ibm) card.
    The program run i can choose the mod an play it blindly but i have a black screen no video.
    If i insert an mda card it works fine but using the cga no.
    The cga card was tested on lots of software and works fine.

    Theres something you have to do to have it working ?

  2. #2

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    Quote Originally Posted by soviet9922 View Post
    Ok, i have galaxy player running on a 286 anda cga (original ibm) card.
    The program run i can choose the mod an play it blindly but i have a black screen no video.
    If i insert an mda card it works fine but using the cga no.
    The cga card was tested on lots of software and works fine.

    Theres something you have to do to have it working ?
    I don't get anything on the screen of my Tandy 1000 EX either.
    My Retro Collection:
    CBM: C64, Amiga 500 x2, 600 & 1200
    Mac's: SE, LC630 & Beige G3
    PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
    FS: Brand New Tandy 1000 Adapters

  3. #3

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    Tried this in emulated PC (in MAME) -- same problem. Looks like a bug in the player -- it tries to write to MDA display memory even though CGA is installed.

  4. #4
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    Huh, I always assumed it didn't support any display on CGA because it remaps the VGA text font for its FFT display. It has a ton of anti-debugging crap in it, but I'll see if it can be patched.
    Offering a bounty for:
    - Documentation and original distribution disks for: Panasonic Sr. Partner, Zenith Z-160 series
    - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)
    - Any very old/ugly IBM joystick (such as the Franklin JS-123)

  5. #5
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    Default

    If it works on MDA, it should be possible to patch that code to work on 80col CGA textmode at least.

  6. #6
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    Default

    Did a quick reverse-engineering of GLX212.
    Conclusion: it accesses the screen via a far pointer, which is initialized to B000:0000 by default, so the MDA framebuffer.
    It uses all sorts of fancy int 10h calls, which aren't supported by MDA or CGA.
    So it 'defaults' to MDA if the int 10h stuff doesn't work, because that's how the framebuffer is initialized.
    If the int 10h calls work, it overwrites the far pointer to B800:0000.

    Simple fix: patch the default value of the buffer, so it is initialized to B800:0000
    I've done this for you: https://www.dropbox.com/s/ce09hcu8ei...X_CGA.zip?dl=0
    My copy was packed with PKLITE, so I used unp.exe first to unpack it. Then I located the pointer, which is at offset 10D31 in the file.
    I changed byte 'B0' to 'B8' there. And there you go.

  7. #7
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    Default

    Quote Originally Posted by Scali View Post
    Did a quick reverse-engineering of GLX212.
    Conclusion: it accesses the screen via a far pointer, which is initialized to B000:0000 by default, so the MDA framebuffer.
    It uses all sorts of fancy int 10h calls, which aren't supported by MDA or CGA.
    So it 'defaults' to MDA if the int 10h stuff doesn't work, because that's how the framebuffer is initialized.
    If the int 10h calls work, it overwrites the far pointer to B800:0000.

    Simple fix: patch the default value of the buffer, so it is initialized to B800:0000
    I've done this for you: https://www.dropbox.com/s/ce09hcu8ei...X_CGA.zip?dl=0
    My copy was packed with PKLITE, so I used unp.exe first to unpack it. Then I located the pointer, which is at offset 10D31 in the file.
    I changed byte 'B0' to 'B8' there. And there you go.
    Hey man your are cool, never imagined that someone could just fix it like that.
    Works great ! Thanks !
    And happy Christmas to all

    Running on my ibm portable original cga green card.

  8. #8

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    Nice, I can't wait to try it on my Tandy when I get home from holidays!
    My Retro Collection:
    CBM: C64, Amiga 500 x2, 600 & 1200
    Mac's: SE, LC630 & Beige G3
    PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
    FS: Brand New Tandy 1000 Adapters

  9. #9
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    Default

    Saved me the trouble, thanks!
    Offering a bounty for:
    - Documentation and original distribution disks for: Panasonic Sr. Partner, Zenith Z-160 series
    - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)
    - Any very old/ugly IBM joystick (such as the Franklin JS-123)

  10. #10

    Default

    Thanks, that's great. The file selector keeps the CGA snow running continuously though.

    I guess I have a christmas-themed modplayer now.

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