I a word, you can't use either SATA controllers or SCSI controllers with MorphOS 2.7 in a Powermac (just in Pegasos computers).

You can boot OSX with an unsupported (by MorphOS) controller of either type.

What Kronos and Moto have pointed to is that since there is a driver for the SIL3X1X SATA controllers in MorphOS 2.7 (that works fine in a Peg), the presence of this controller in a Powermac (which it isn't supported in yet) prevents the machine from booting.

I actually have an SCSI2 controller (with Mac compatible firmware) that isn't supported by MorphOS hooked to an external SCSI drive that I can power up or leave off. This makes foe a convenient way to dual boot.

However, I'm already planning to replace this set up with the SIL3512 card I just acquired when MorphOS 3.0 is released. As I can't access the SCSI drives under MorphOS, this will be a big improvement for me.

And I'll just move the SCSI drives to one of my PCs. They make great backup drives (really fast backup).

SCSI while not completely dead, has been supplanted by SAS anyway. And SATA offers us much of the same benefits with easier to get, cheaper components.