With all the hoohah about Boot Camp and Windows on Mac, I’m amused as heck by this discussion that shows how frickin’ difficult it is to run Mac software earlier than OS X on an Intel Mac.
‘Course, I haven’t had the need to run Mac OS 9 or earlier software since well before I upgraded to Tiger last April, so I doubt many people need to do this — and if you do, chances are good that you’ve got an old PowerPC Mac lying around for the purpose. But just in case you need it, have fun with your ROM files.
Wha?!? OK, questions:
1) Is the problem running earlier OS software on an Intel Mac, or is it running earlier OS software on OS X? If it’s the former, why is OS X different on an Intel Mac than it is on a Motorola Mac (or whatever chip they used to use)? I can’t think of another example where an OS supports software on one hardware configuration, but not another. That’s the whole point of OS, isn’t it? Obfuscation layer between the apps and the hardware?
2) Who’s writing these Mac emulators that run better on Windows than they do on Macs?!?
Apple dumped support of the Classic layer on Intel machines, which was basically a virtual machine that ran OS 9 in a separate compartment. My understanding is that the reason for this is that OS 9 does numerous direct calls to the processor (some of its code is very old), and so it would be impossible to trap for all of those calls.
The Windows emulators work by emulating a 680×0 chip in its entirety, so there’s a different level of abstraction preventing a crashing call to an Intel chip. You can also emulate those chips on a Mac, of course.
Yes, you’re right, the whole point of the OS is to separate the software from the metal — and Classic Mac OS wasn’t great at this [1], which was one of the driving factors for the switch to OS X.
[1] Notably, many of the times they did do this, it was to get some phenomenal performance gain — Apple many times got Classic Macs to do things they weren’t supposed to do. I recommend you read up on some of the magic they pulled on the first Mac at http://www.folklore.org.