Thanks for the info. 
I'm sort of referring to things like x86's way of abstracting usb AND ps/2 keyboards into it's 0x60 port. You use 0x60 and you know you have keyboard support (though basic) if one's plugged in somewhere. Also, 0x0000b6 (I think) is a default location in memory where you can directly alter the graphics bitmap.
Is that way of using generic drivers possible on PPC? that's what I'm trying to get at. Does PPC have hardware "givens"?
I'm not sure. Correct me if I'm wrong, but recall that the standard for x86 machines isn't the x86 itself, it's the fact that they're all technically derived from the standard architecture of the 1981 IBM PC. PPC architecture never really had a standard reference model like that (at least, not with the dissemination and manufacturer buy-in of the PC). As Piru says, Macs are the closest thing.
