OS4 Classic, why disable the 68k ?

[cgutjahr]

But if WarpOS+ 3.x managed to do that it must be feasible ;-)

It is feasible, but it would slow down the PPC CPU considerably: Each time you switch from one CPU to the other on a PowerUp board, you have to flush all CPU caches (because the CPUs are sharing the same memory, and this is the only way to maintain memory integrity). Now imagine doing that hundreds of times per second (as you would have to, when running 68k and PPC tasks in parallel) - the system would crawl.

As it is, depending on the speed of your PPC CPU, the 68k CPU emulated by OS4 is definitely faster than a 68040 anyway.

[cgutjahr]

as i was talking about classic version, I cant see how the PPC side of my blizard ppc at 240mhz can be faster emulating 68k than my real 060 onboard...

Just give it a try, and draw your conclusions after you saw it in action. Apart from stuff that hits the CPU badly (like, say, Maxon Cinema rendering a scene) you probably won't miss your 68060. Having the whole OS running on the PPC makes a whole lot of a difference.

A lot of OS4 software (read: ports) is running way to slow on OS4 classic, because the PPC CPU is really not all that powerful. But I don't think 68k software is a problem. Anybody still using Maxon Cinema t render scenes on real Amiga hardware belongs into a mental asylum anyway