DOS driver

This is a fully featured driver for DJGPP and allegro. It supports many VGA modes, VESA 1.0–3.0, VBE/AF, S3 and some other cards.

The following problems may occur:

Some DPMI servers like the one from Novell/Dr/Open DOS are buggy. Use clean DOS instead and XaoS will automatically start cwsdpmi. Under Open Dr DOS use dpmi off at command line to disable it.

If your videocard has enough memory for the selected resolution, you most probably have an unsupported videocard. Please use a VESA BIOS extension on this videocard. (See the note about VESA at the end of this section.)

I don’t distribute a coprocessor library linked into XaoS because it is too slow for a real-time zoomer. Coprocessor emulation will not help, because xaos works in protected mode.

This could also be caused by Allegro’s slow driver or your videocard’s VESA BIOS. You could try some other VESA BIOS extension instead. Look at the for the FreeBE project or Scitech Display Doctor package. (See the note about VESA at the end of this section.)


VESA is a standard for using higher resolutions in DOS. Many videocards have VESA support in the BIOS so you don’t need any additional software, while others need support from a special program. Also some VESA BIOS implementations are buggy or suboptimal; there are 3 different versions, version 1.0 is many times slower than 2.0, which has support for protected mode and linear framebuffers. So if you have problems with higher resolutions, or some graphics modes are not available (like 320×200 truecolor), you might try some software package which emulates VESA.

The most famous VESA emulating program is Scitech Display Doctor. It has support for many videocards and is quite reliable. It’s disadvantage is that it is shareware and works for only 30 days. You might also look on, where there are many VESA emulation packages such as s3vbe or the new FreeBe project at

DOS driver was written by Jan Hubicka, 1997.