On 20205-09-23 at 18:03 John Paul Adrian Glaubitz wrote:
AFAIK every installation CD or Boot-CD for Mac OS X works on every PowerMac, Power Book, eMac, iMac,...I actually never thought about this but now you're saying it, it absolutely makes sense. Has it ever been confirmed that Apple shipped different versions of MacOS X with different PowerPC baselines?
If it doesn't work it's simply because a newer Mac would require drivers that are not there in older versions of Mac OS X.
Example: The Mac mini G4 from 2005 officially only supports Mac OS X 10.3.7 and up, the Late 2005 however came with 10.4.2. I tested this thoroughly in the past and can confirm that it boots 10.4.0 as well as 10.3.0, but with missing drivers.
I also tried 10.2.x on the Mac mini G4 and this also works. There is a driver from ATi for the Radeon 9200 and then this also works. Bluetooth and WiFi, but most important the throttling of the fan (thermal/energy/throttling management) doesn't work though. Again, lack of drivers, but overall it boots and works.
All my Power Mac G4s from 1999/2000 boot every Mac OS X for PowerPC that ever came out, including Mac OS X Server 1.0 (Rhapsody 5.3+) for PowerPC and including the unsupported Mac OS X Leopard (10.5) which requires a faster CPU.
Long story short: the ONLY ONE version of Mac OS X I know of that is specific to a certain Mac is 10.2.7 G5 (and the 10.2.8 update). Again, this is due to changed hardware as 10.2 only supported G3-G4.
Rhapsody is the only "Mac OS X" I know of that supports the G2 (PowerPC 603) as well as the G3 (PowerPC 750). I've never tried the original Rhapsody 5.0/5.1 (that didn't support the G3) on a G3 or G4.
However, if I remember correctly, the big problem was Open Firmware. There are OldWorld- and NewWorld-Macs, and to get the operating system compatible with both was a "biggie". (I read in book somewhere that Apple spent quite some time to make the boot process stable.) The rest is CPUs and drivers. Naturally an OS for the G4 won't run on a G2 or G3, or even the original PowerPC 601, because of missing functions, but so won't Windows on a PC when the CPU lacks support. Example: Windows 7 x64 used to run on Intels first x64-CPUs, but Windows 8 x64 wanted extra functions (specifically CMPXCHG16b, PrefetchW, LAHF/SAHF) and so this update stopped working e.g. on a PC of mine, because the Intel Pentium D 8xx (Intel 64 supported) lacks PretechW and Windows 8.x/10 wouldn't start. An Upgrade to the Pentium D 9xx solved this. The same is true for newer Windows 11 builds, which also need a function in CPUs that is simply missing in older CPUs (Windows 11 24H2 requires SSE4.2).
TL;DRNo, with the one exception of Mac OS X 10.2.7 G5. There were OEM installation CDs/DVDs for specific PowerPC Macs, but this is always the same unmodified Mac OS X build, only with added drivers. Those drivers were then included in the next updated Mac OS X version, so the next generic Mac OS X installation disc will always boot on every previous Mac with G3, G4 and possibly G5 processor.
Cheers, Mac User #330250