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A 32-bit CPU with MMU is not a prerequisite for multitasking. The Amiga (and others) managed preemptive multitasking on a Motorola 68000.

For designs that wanted an MMU, you could use an external one. Sun had external MMUs in their early workstations. Even Apple had their own MMU in the Macintosh II line before they switched over to the 68030.

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> Even Apple had their own MMU in the Macintosh II line before they switched over to the 68030.

You could add a 68851 to a Macintosh II, I didn't think Apple developed their own MMU for it. The Lisa had a custom MMU.

Ah, I misremembered. Wikipedia's Macintosh II page says:

"The machine shipped with a socket for an MMU, but the 'Apple HMMU Chip' (VLSI VI475 chip) was installed that did not implement virtual memory (instead, it translated 24-bit addresses to 32-bit addresses for the Mac OS, which would not be 32-bit clean until System 7)."

Minix, PC/IX and Microsoft/SCO Xenix were indeed multitasking systems (well, Unices) running on the 8086

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