Conveniently both your examples have received technical deep dives by Fabien Sanglard, who has made both the relevant texts freely available in PDF form [0][1].

Conveniently both your examples have received technical deep dives by Fabien Sanglard, who has made both the relevant texts freely available in PDF form [0][1]. Mode-X was an annoying video mode to actually make use of without a performance hit. So despite its highly desirable combination of square pixels and 256-colors, it didn't see much use in games from the DOS days. 13h (320x200x256) was far more common because of its contiguous, linear frame buffers. Mode-X needed annoying bank switching where the first bank had pixels 0,4,8... and second bank pixels 1,5,9... and so on. The VGA was such a PITA. [0] https://fabiensanglard.net/b/gebbwolf3d.pdf https://fabiensanglard.net/b/gebbwolf3d.pdf [1] https://fabiensanglard.net/b/gebbdoom.pdf https://fabiensanglard.net/b/gebbdoom.pdf