No idea I only play on MacOS classic.

But is it the same of windows version, for curiosity?

I use version 1.2! As it runs fine under 68k mode, and on my PowerMac as well!

A quick search shows me, it’s still on Macintosh Garden!

Which Simcity for MacOS? Can you indicate me which version is it (i.e. website describing it and how to download it)

A lot of things back then were tied to timings you’d expect on real hardware, and I wouldn’t be surprised at all if some things are totally screwed up with a substantially faster cpu/video/ram/disk access. I’m afraid all I can say is that you are best making single changes, and measuring/observing what is going on, and seeing what if any changes make an impact. Many people make LOTS of changes all at once, and have no idea if or what did anything, so I do one at a time, but make more extreme variations, no need to start single stepping!

Yes, I am indeed using GNU/Linux, so I will try changing the process niceness.

Please let me do another question, since you are giving me the answers I have been searching online for a long time:
Lemmings on the Quadra 800 under qemu-system-m68k has audio problems if I force vsync on the host (by passing SDL_RENDERER_PRESENTVSYNC to the SDL_CreateRenderer() call in QEMU).
That happens even if I set a 66.662467 Hz physical video mode on the host, which is what the Mac II originally used.
That leads me to think that old Mac games expect asynchronous video refresh, ie: not waiting for vblank, using internal timers instead to keep an adequate framerate (but full of tearing in scroll sequences).
Am I right? Or is Lemmings for example expected to move smoothly on a real Mac II? How do games manage the fact that after the first Mac II there where a plethora of VGA video modes available they would run on?

Yes it is expected behavior. I guess if you are using Linux you can try to renice it to a lower priority, or set the affinity and priority on Windows task manager.

68000s like other processors before them really didn’t have anything mobile in mind. You see the same thing with MIPS or other processors. It’s a pitty it doesn’t have a cycles per second cap like BOCHS or 86Box

Many thanks for your answer, really. There isn’t much info around this anywhere.

So, just to be sure, running Quadra 800 + System 7/8 on qemu-system-m68k AND seeing that 100% CPU usage is expected, right?

I mean, the only current way around it would be running the A/UX on the Quadra 800 emulation, is that correct?

fundamentally the 68000 has no ‘idle’ instruction to catch so it’d require profiling like dynamips, or the injection of an illegal instruction from a task with the lowest priority.

As far as games go , I mostly like SimCity on MacOS. I’m sure plenty of others run though!

I am asking all this here because it’s the only place I could find where the idle loop problem with Quadra 800 emulation on QEMU is mentioned…