comments:
If you're coming up through the real-mode/PCBIOS path, your options are VESA (INT 10h, AH=4Fh, AL=subfunction but IIRC 02 sets video mode), traditional video services (INT 10h; AH=0 sets mode), and direct programming of the EGA/VGA legacy hardware. Of course, you could implement your own custom driver or rejigger-kludge an existing one, but that takes more effort and know-how. For the first two, Ralf Brown's Interrupt List (raw files etc.); this includes a list of ports also for the third, but imo a book is better (e.g., this is a good 'un). Or for the third, grab VGATweak.zip—I have a copy here. It includes sample code (DOS C), sample register dumps, and an interactive register-tweaking tool (for DOS/Win). However, once you get outside the stuff that (a.) readily fits into VGA memory, and (b.) has a standard resolution in terms of pels-to-pixels ratio, you real quickly find that all monitors don't sync the same, and some perfectly legal modes will send a venerable CRT into a seizure of relay-clicking and flyback transformer whine—ofc flat panels tend to DPMS blankly at you instead, which is less exciting for the youthfsths. So 400×300, sure, probably yes. 480×360: very likely. 480×600, much less likely, and for anything over 320×200 you're either going to be in a planar mode (which takes Tricks) or stuck dithering away in ≤16 colors (with each change of foreground application causing a repaletting that looks … just atrocious), or both. I'm pretty sure 800×600 is only achievable qua VGA mode by using SuperVGA memory size with nonstandard timings and limiting yourself to 16 colors (planar), so I'd assume 480×600 is kinda in the same bucket. So what I'd do is capture a dump of some text modes— 20×6.25 for 4× text zoom-and-pan, 40×12.5 for 2×, 80×25 so you can reboot or go on real-mode sabbaticals cleanly, plus 80×43 and 80×50 configs for actual use, —and graphics modes— 320×200×256 (INT 10h, AH=0, AL=13h), 320×240×256, 400×300×256, and 480×360×256. These are most likely to work and look good (aim for x:y ratio ≈ 4:3, or, if you want to stretch to fit 16:9ish, something rather wider), and you can use a kernel command-line parameter to pick the mode to boot with, which your video driver uses for init. 320×200×256 is unsatisfying on some fronts, but it's dead easy to use, so I'd start there. If you don't want none of that, set Mode 13h on your way in.