Comment by laurencerowe

Though like AmigaOS, Windows 95/98/ME still lacked memory protection. It wasn't until Windows 2000 brought NT to the mainstream that memory protection became common, and probably Windows XP until it became ubiquitous after 98/ME stopped being shipped on lower spec home PCs.

Interesting to wonder what an alternative timeline would have looked like where Acorn used QNX instead of trying to build ARX (the Mach microkernel based system abandoned for Arthur.)

ARM had memory management from the outset, but memory was too expensive to consider anything like unix for the base systems (the alternative RISC iX BSD derived OS required 4MB.) And the context switching overhead would probably have made the desktop experience worse even if they could afford the memory.