Image Map Image Map
Results 1 to 6 of 6

Thread: CGA card with dual composite output?

  1. #1

    Default CGA card with dual composite output?

    I have this CGA card which I bought from Bulgaria hence it's presumably from Pravetz-16 computer. The composite output is much lighter in color than the other card from USA. However the interesting part is that there's second composite output which gives me different color layout and I have no idea what it was be made for. Light pen? It's not negative picture.

    Reportedly there exists also Pravetz models with PAL composite format too but I checked that the composite is not PAL format as my PAL TV shows the picture only in black and white so it's definitely NTSC.

    IMG_1799.jpg IMG_1800.jpg


    The card looks almost identical to this:

    Last edited by musicforlife; July 15th, 2018 at 04:32 PM.

  2. #2

    Default

    Are you sure it's CGA and not EGA?

    Dual RCA jacks is indicative of EGA.
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  3. #3

    Default

    Quote Originally Posted by Stone View Post
    Are you sure it's CGA and not EGA?

    Dual RCA jacks is indicative of EGA.
    I'm using it in my IBM 5150 with switch setting for CGA, so I'm quite sure that if it would be EGA, the IBM would notify me with errors. EDIT: I tested games which offers CGA/EGA and each time they only recognized CGA. Also EGA would require its own bios rom and that doesn't exist in this card.
    Last edited by musicforlife; July 15th, 2018 at 05:22 PM.

  4. #4
    Join Date
    Jan 2013
    Location
    Marietta, GA
    Posts
    3,255

    Default

    The second one might have the composite colors optimized for monochrome screens. That would make sense if the primary uses the same composite colors as the older IBM CGA cards. The later ones changed the colors a tad so the monochrome IBM Portable would not have to deal with colors that were the exact same shade of gray.

  5. #5

    Default

    Quote Originally Posted by musicforlife View Post
    Hm... I would guess that this output was meant for black-and-white TVs. The color burst signal may actually be missing, but your TV is still expecting one; so it tries to amplify what is basically noise where the burst should be. This results in smeared and exaggerated phantom "colors", especially around edges.

    My own TV sometimes behaves this way when the CGA sends out a B&W signal. This game is using mode 5 so the color burst is completely disabled, but you can actually see distinct "colors" here:

    jbird_b&w.jpg

    It should be interesting to see what you get if you run Trixter's CGA Compatibility Tester and view the composite monitor color charts through that output.
    Actually, it should be interesting to see photos of those through the other output too, because that one looks sort of unusual as well.
    int10h.org :: :: :: blog

  6. #6

    Default

    Quote Originally Posted by SomeGuy View Post
    The second one might have the composite colors optimized for monochrome screens. That would make sense if the primary uses the same composite colors as the older IBM CGA cards. The later ones changed the colors a tad so the monochrome IBM Portable would not have to deal with colors that were the exact same shade of gray.
    That makes sense, as the second output produces much cleaner text in the screenshots above.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •