For anyone interested, it turns out
Apple introduced a bug within the Mac OS ROM file itself, starting with ROM version 8.8, which causes some graphical glitches with at least a few games on both ATI and NVidia GPUs (and somehow NVidia GPUs seem to have some other additional issues with them regards of ROM version). The issue is seemingly unrelated to the GPU and GPU driver version.
Thing is, the previous ROM version, 8.7, is totally fine and free of this problem.
At first, it was misattributed that Mac OS 9.2.2 was behind the issue, whereas 9.2.1 was fine, but I booted 9.2.1 on the mini (yes, it turns out that version of Mac OS can also boot in the mini as is), and confirmed the issue was still present.
Because the hacked ROM we use for the Mac mini is based on ROM version 9.6.1.It turns out ROM version 8.7 works perfectly fine with Mac OS 9.2.2, too, but the question is: if we patched ROM version 8.7 with all of the patches from @ELN & gang, would that be sufficient for the
Mac mini G4 to still boot?
In the past we used I think the Sawtooth ROM, right? Then we switched to a G4-Cube-based ROM, hoping to address some issues. Could it be the Sawtooth ROM we had was v8.7 or lower? If so, it could be used to play those games. Else, we will need to patch ROM 8.7 with the Mac mini compatibility and see.
The following games are affected:
-
The Labyrinth of Time-
Uncharted Waters II-
Yoot TowerThere's also a special case of a crash (rather than color corruption) that happened with
Eric's Cascade, but we don't yet know if this one is because of Mac OS ROM 8.8+ as well, or if it's with an issue with Mac OS 9.2.2 itself that is not present in 9.2.1. We should check by trying to run it under 9.2.1 with the same ROM we already use. My bet is that the ROM is the culprit again, OR, this one has nothing to do with the ROM and it crashes Mac OS 9.2.1 and 9.2.2 both.
On a side note, for Mac OS X users out there (switch back to 9!
), under Classic this also happens even with ROM 8.7. Presumably Classic overrides the Mac OS ROM file, and Classic's replacement has the same issue. At least some versions of Classic do.
EDIT: Fixed broken hyperlink to the discussion from where the findings originated.