How does preemption work on a processor that barely has interrupts and has no way to recover state after a page fault, in an OS that has to fit into a couple dozen kilobytes of ROM?
There were plenty of preemptive multitasking systems for the original 68000, and regardless page fault recovery was fixed from the 010 onwards.
And certainly was very not a problem on PowerPC which TFA is about.
Also not sure how you can say the 68000 "barely has interrupts" I don't even know what you're on about.
MacOS was broken because Jobs forced it to be that way after he was kicked off the Lisa team. Which had a preemptive multitasking operating system on the 68000.
Preemptive multitasking is unrelated to page faults. And the 68k handled page faults just fine starting from the 68010.
Space constraints were certainly limiting on the earlier models, but later ones were plenty capable. Apple itself shipped a fully multitasking, memory protected OS for various 68k Mac models.
By the late 80s, the only reason the Macintosh system was still single-tasking with no protected memory was compatibility with existing apps, and massive technical debt.
Later Mac ROMs were 512KB, same with the later Amiga Kickstarts (3.x) That was a lot of space for the late 80's and early 90's. Interrupts were supported (8, if I recall.) And 68000 machines didn't support virtual memory until the 68010 and later, so no issues with page faults.
I still remember the day teenage me got an Amiga 500 with a whopping 512K of RAM, and witnessed the power of multitasking, way back in 1988.
The Amiga had preemptive multithreading with multiple task priorities on the original MC68000. Preemption is distinct from memory protection or paging.
