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Is 640x480 8bit a standard VGA mode?

Hi,


I am doing some graphics programming, and i want to

do 640x480 8bit in standard vga,

ie int 10h sub-function 0h (set video mode). My guide

only lists upto mode 10h, but i know there are more

modes than this.


If this is possible, could someone tell me the mode #

and memory segment. I dont really want to do SVGA or

VESA programming.


aXis







Comments

  • No, the standard vanilla VGA (I have one somewhere,

    it's on a 386 back home) only supports one 256-color

    mode, 320x200 (and ModeX stuff, but that's another subject...

    It does support 640x480x16c, and other high-resolution

    VGA modes, but that's about it. I'm afraid if you want

    mid to high-res 8-bit graphics, your going to have to use

    VESA (Or just write it for a couple of cards... not a good idea.)

    You can find fairly good documentation at: www.vesa.org.

    If you can't find it, or just don't want to look for it, mail

    me and I'll mail it to you.


    Matthew Gross

    Acheron@Hotmail.com





    URL:http://acheronx.ml.org/home/

  • Hi,


    I know of another screen mode, commonly referred to as Xtended Mode. This is very much the same as ModeX, except it is 640x400x256. I don't think this mode is supported by the good old VGA cards, but most people have SVGA in their PC's today, and as far as I know, most SVGA cards do support this mode (you don't have to know anything about the different chipsets, or VESA for that matter. You only need VESA once when you call BIOS for the screen mode change, but other than that its simply like ModeX, only more pixels :). The screen buffer is at segment 0A000h, as usual, but one screen fills almost the entire segment, so you cannot page-flip (it is unchained, though, and NO bank switching!). I have the details somewhere. You could find it on the internet if you search for PCGPE, which stands for PC Games Programming Encyclopedia. This is a very useful set of docs covering all kinds of topics like sound, graphics, file formats, input devices, and more. Among these is the document on Xtended Mode. You can also email me, and I can send you the doc, or the entire PCGPE if you want (about 700k, or twice that if you also want the Windows .HLP version of it).


    Greets,

    Mark


  • Actually, most old VGA's support it... it's the newer ones that have problems. I've done

    a library on it, and tested it on all the cards I've been able to get my hands on so far...

    It works rather nicely, but is hard to buffer since it does take up 640x400 bytes a screen.

    ATI cards inparticular have a severe problem with Xtended Mode. There's a compatability

    chart on my webpage if you're interested.


    Matthew Gross

    Acheron@Hotmail.com





    URL:http://acheronx.ml.org/home/



  • Why is it then that many old vga cards have

    video ram up to and even over 500K. what is all

    this memeory used for if there is only one 8bit

    mode?


    I suppose it could have been a crude extention

    towards SVGA.


    Thank for your help anyway,


    aXis


  • A lot of the earliest SVGAs did not identify themselves

    as such, as the terminology had not come about at the time...

    for example, I have a 768 KB VGA Wonder in an old 286, which

    is actually a SVGA card, in spite of claiming to be VGA.

    To return more info on a VGA card, you can try my test program

    for a game I've been working on... It's listed as a graphics demo

    on the page below, but it's really a hardware-compatability tester.

    It'll test the given hardware for ModeX compatabilty and Xtended

    Mode compatability. If you don't mind, send me the results, as I'm

    trying to expand my database on Xtended Mode compatability, which is

    located at: http://acheronx.ml.org/home/xtended.htm

    If you want furthur utils on testing out VGAs andd SVGAs, just mail

    me.




    URL:http://acheronx.ml.org/ukpub/

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