Changes
SymbOS
,IBM shows already in the 80ies and the 90ies that processors without stack can do multitasking e.g. MVS (XESA)
== Technical background ==
Even the Z80 8-bit CPU is able to run a pre-emptive multitasking environment. Missing mechanisms like memory protection, which are often called as a condition for multitasking, are system stability issues only. The MP/M operating system already proved, that multitasking on Z80 computers is possible, but it was not executable on home computers. Today different implementaions of multitasking OS exists for Z80 based systems e.g. Roseanne for the PcW or Doors for the Spectrum.
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