Julian Thornhill <jth@ion.le.ac.uk> wrote:
I have a newly delivered desktop system with an AGP graphics card that has a
Rage Mobility P chipset. (Well that is what is written on the chip.) Photon
1.14 traps it as requiring a rage driver. At 1280x1024 resolution everything
works fine. At lower resolutions the displayed image ALWAYS has a refresh
rate of 60Hz - the photon control panel allows different refresh rates to be
selected, but that is not what comes out the video connector > 
I’ve tried the latest beta graphics driver package, but this did not help.
At the moment I’m trying to resolve this by getting a different graphics
card, but if QSSL has an interest in fixing this bug for other users then
I’m prepared to struggle on a little longer. Please let me know what you
wish to do.
The problem with the Rage II/Pro/Mobility P chipsets is that we
use the BIOS to perform modeswitching. This is by far the most
reliable way to handle those particular cards, but the range of
resolutions and refresh rates is restricted to what the BIOS
makes available.
These refresh rates are generally available on most ATI BIOS’s:
640x480 : 60, 85, 75, 72
800x600 : 75, 72, 60, 85
1024x768 : 75, 70, 60, 87, 85
1280x1024 : 75, 70, 60, 85
As chips become fancier and more complex, so must the BIOS in order
to support new features. But the BIOS can only be so big, since
it has to fit inside its little legacy-ISA-x86ish aperture.
What I suspect is happening is that ATI are leaving out mode tables
in order to save space. Certain other vendors have even been
known to limit BIOS resolution support to 800x600, and others to 640x480.
The good news is that ATI have made it much easier to write a driver
which does not need to call the BIOS, with their newer chipsets.
Hence the Rage128 driver can support lots of resolutions and refresh
rates, irrespective of what the BIOS provides.