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Where can i find some vesa tutorials? I need some code to change the video resolution using physical ports. Thanks

You can get the VESA documentation from
  
  http://www.vesa.org/vbe3.pdf

I think the documentation is more than enough to get started. And the doc also contains C code to test your display adapter. I tried on my adapter and was able to get all the supported reso.

regards
ksk

PS: Actually it was gaffi who gave me this link. I sincerely thank gaffi for that.

Vesa uses interrupts, not ports, for its interface.  And real mode interrupts, at that (apparently version 3.0 supports pmode interrupts, but very few cards support vesa3.0).

If you want to use ports, you'll have to write a separate driver for each video card (lookup VGADoc for a collection of hardware/port APIs of common chipsets).

You'd be better off writting a vm86 handler, and emulating the Vesa BIOS (int 0x10).

Cheers,
Jeff