Hello,

> pci1 at ppb0 bus 1
> pci1: i/o space, memory space enabled
> ahc0 at pci1 dev 4 function 0: Adaptec 2940B Ultra2 SCSI adapter
> : unable to map registers
What does scanpci -v say about the card?

> Fatal server error:
> xf86MapVidMem: could not mmap screen [s=20000,a=a0000] (Invalid argument)
That's XF86's vgahw module which can't access VGA registers on macppc - I have a patch to make it work in a way but it's dangerous because there's (currently) no way to check if it really got the registers so it could program your video card to some very odd frequencies and probably toast your monitor, although modern monitors ( less than 8 years old or so ) should just shut down when they can't make sense of the video signal.

good luck
Michael