IMS TwinTurbo - wrong colors

[fab <plain@gmx.net>]

Hi,

I am using Debian/Woody on a PowerMac 9600/350 with an IMS TwinTurbo 
graphics adapter and have the following problem when
using XFree86 with the imstt- or fbdev-Driver :

- the colors are only correct when in 8-Bit-Mode
- 16 bit depth yields in "psychedelic" color shifts
- when using 24 bit depth, red shows up as blue, and everything
  that is meant to be blue appears as brown

This problem occurs with kernel image 2.2.20 and with xserver version 
4.1.0.1

Was anyone successful to get the xserver working in more than
8 bit on a stock 9600/350? Anything I could find on the web on that
topic didn't lead to anything so far, so any help would be
appreciated.

Thanks in advance,

Quantum