I finally had success getting this card to work with
xstart. The answer I found was to use XF86Config (graphical)
and choose the unsupported VGA card then details. If you
choose the Mach64 in details the proper Ramdac does not
show up in the list. My Superprobe:
First video: Super-VGA
Chipset: ATI 88800GX-D (Port Probed)
Memory: 2048 Kbytes
RAMDAC: ATI-68875/Bt885/TLC34075 15/16/24-bit DAC
(with 6-bit wide lookup tables (or in 6-
(programmable for 6/8-bit wide lookup
Attached graphics coprocessor:
Chipset: ATI Mach64
The Bt885 does not show up when you choose the ATI
selections and apparently thats what is needed.
Its still not perfect but it works. The readme.atimach64
says the ATI ISA card will not work. But this method gets
xwindows 16 colors to work.
What is the exact model name of your card? Also is it PCI or is it
ISA? Lastly have you tried using Xconfigurator and choosing the ATI
Graphics Expression choice that has the 68875 listed in its name?