Apple tried to make the MacOS 68040 compatible but they also tried to keep it from being 68060 compatible, especially after a 68060 Amiga became the fastest Mac. Did you notice how the older MacOS 6-7.5 versions were more compatible with the 68060 than the later ones?
There was no difference with OS8 in 060 compatibility. The patching was pretty much the same. Apple didn't "try" to make the Mac OS non-compatible with the 060. There were several Mac accelerator companies chatting with me about patches needed to make the 060 work, and it was agreed by everyone that there was no deliberate act to make sure the 060 didn't work. It just turned out that Apple did a lot things that killed the 060's expanded architecture.
The 68060 is much more than a number crunching can't branch DSP. Branches and loops became much faster not that the 68040 was bad (the 68060 is good even compared to modern processors). You may have disabled the branch cache, turned off superscalar execution and used 1/2 I/D caches for maximum compatibility though. I would expect a 68060@50MHz to still run faster than a 68040@33MHz with all this disabled.
Unfortunately, that was not the case. The various Mac benchmarking programs showed only minor improvements in certain benchmarks with the 060. SuperScalar always had to be off, and there was a limited amount of branch caching allowed in certain portions of the OS code, and the instruction and data caches were toggled off and on without anyone realizing it. Surprisingly, memory functions were quite a bit slower with the 060. We could compare the 040 speed vs. 060 speed using the same Phase 5 setup, just swapping the CPU card. So, the memory was the same.
Keep in mind that the FPU was the Mac's biggest asset for the OS. This is why you didn't see many LC (or any EC) CPUs going into Macs. The MMU was needed of course for virtual memory. The FPU was used by EVERYTHING in the OS! The position of where to draw a pixel on the display was calculated by the FPU, not the CPU because it was faster to do it this way. When Joe and I re-wrote Apple's PACK4 and PACK5 in full assembly (like everything else we did), we actually broke most current benchmark programs in the FPU tests and we made the Mac insanely fast - to the point where production studios like Amblin Entertainment were using Amigas with my Mac emulation to run Avid video editing suites because that setup would run circles around real Macs... and they could also use Lightwave for rendering too.
Apple didn't "brainwash" me. I reverse engineered their entire OS and custom hardware. I know how their stuff worked better than anyone.
