I'm a little confused by resolution selection, and making sure that a game picks the right resolution. What I mean is, several resolutions are duplicated in the different Khz modes, i.e. 640x480 can be selected in either 15khz mode or 31khz mode. When setting resolutions via mame ini's or the Quickres taskbar, all it lists is the resolution though, not the khz mode. So how do I make sure a game is selecting the 15khz-mode resolution and not the 31khz-mode resolution?
Ah... now I got it
The "lowres" (less than 350 lines) Modes (say 384x240) are not doubled and only available in 15KHz.
The "medres" (between 350 and 440 lines) resolutions are only available in 25KHz.
The "highres" (more than 440 lines), can either be 15KHz or 31KHz, however, If you choose 15+31KHz the same time, the 15KHz modes will be REMOVED and only the 31KHz will be added.
So there is be only 1 Frequency (either 15/25 or 31 KHz) per resolution.
There is a simple rule.
15KHz is basic.
25KHz overwrites 15KHz.
31KHz overwrites 25KHz.
So if you got a 640x480 definition for every Frequency, the 31KHz one will be the one selectable in Windows, and the otheres will be droped and cannot be selected.
IF you find ALL your resolutions beings doubled to 31KHz (or more) you most likely got an NVidia card and have more than 32 resolutions defined. This is due to a Bug in the ForceWare and can only be corrected by using less resolutions, most likely by disabling some unusual 15KHz resolutions.
(remove xx,yy in customZZkhz.txt)
resolutions that I would "remove":
(custom15KHz.txt, games will use 256,240)
(custom25KHz.txt, games will use 512,384)