How to use video pages in mode 13h using ports or Bios stuff?

I dont want to use Video buffers, so can anyone answer this?



Oleg


Comments

  • : I dont want to use Video buffers, so can anyone answer this?

    :

    : Oleg

    :



    this is not possible in mode 13h. in mode13h you have only one page. you would have to switch to mode x, but it is usually faster to use mode 13h and an offscreen video buffer




  • : this is not possible in mode 13h. in mode13h you have only one page. you would have to switch to mode x, but it is usually faster to use mode 13h and an offscreen video buffer

    :



    What is mode x?


  • : : this is not possible in mode 13h. in mode13h you have only one page. you would have to switch to mode x, but it is usually faster to use mode 13h and an offscreen video buffer

    : :

    :

    : What is mode x?

    :



    that's if you turn off the chain-4 mechanism

    and some other crap, and you can make use of the vga's whole video ram (256k, not only 64k as in mode 13h)

    however, plotting pixels is slower, because you sometimes have to do a port access. for some wicked modes (320x240, 320x400 etc.) you even HAVE to use mode x, since a 320x240 pic doesn't fit into 64k



    oh yes, some ppl say that only 320x240 is the true mode x and some have even other definitions for it :P



    anyway, don't ask me how to actually initialize mode x, because it has been ages since i programmed under dos and i'm at the moment very happy with opengl (and sometimes openptc, which is a neat front end for directdraw) and besides, rendering to an offscreen buffer is usually the best way to avoid flickering.



    if you want real info, search for it on http://www.hornet.org




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