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Thread: EGA and 64 colors mode

  1. #11

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    Quote Originally Posted by VileR View Post
    I don't know of any way for an EGA card do display 64 simultaneous colors in any mode (there aren't enough bitplanes).
    I wouldn't bet on that... What about changing the palette after each scanline ?

    This is called split-screen but I don't know if is easy or doable on PC's. You need interrupt and cpu-cycle perfect timings...

  2. #12

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    Quote Originally Posted by vwestlife View Post
    The second Rambo image looks like it's truly to emulate the Commodore 64 color palette. Maybe they got lazy and just copied the artwork from the C64 version of the game?
    They didn't do that with VGA or straight EGA, so it doesn't seem probable that they'd specifically get lazy with the 'extended' EGA version. I'd say it's probably a coincidence of the game trying to set up an extended palette which isn't available on an IBM EGA, ending up with the wrong one.

    Quote Originally Posted by Retro Canada View Post
    I wouldn't bet on that... What about changing the palette after each scanline ?

    This is called split-screen but I don't know if is easy or doable on PC's. You need interrupt and cpu-cycle perfect timings...
    Sure, CGA and VGA can do that (for different color counts, of course) so it should be just as doable on EGA. You don't need cycle-perfect timing, just an interrupt or polling the status registers should be enough.

    With an extended EGA card that supports 6-bit palettes in 200-line modes, that could conceivably get you 64 colors *over the time of one frame*, but that's not truly 'simultaneous' since the palette registers don't hold more than 16 colors at any given instant.
    Probably a moot point in this case anyway, since none of the above photos appear to show more than 16 at a time.
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  3. #13
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    Rambo III (and other Bananaware-developed titles for Taito) supported picking any of the 64 EGA colors in 320x200 if you had a Boca or Paradise chipset. They supported this because they also supported VGA, and the graphics for that game were 16 colors using a custom palette (likely ported from the Atari ST version). The additional color flexibility meant the graphics could look closer to the VGA 16-color graphics.

    However, I don't think that's what Ironman is doing. When run with game /ega64 it shows an image also drawn in 8 colors but it chooses different colors. Running in an emulator, I can see /ega64 mucking around with registers, so I'll see if I can disassemble the code and figure out what's going on.
    Last edited by Trixter; October 11th, 2018 at 09:42 AM.
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  4. #14

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    Difference is between monitors. IBM EGA cant handle /EGA64 mode. Multisynch EGA monitor can do it

    Multisynch monitor in /EGA64 mode
    IMG_7227.jpg

    IBM 5154 monitor in /EGA64 mode
    IMG_7257 (1).jpg
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