Comment by fulafel
1 day ago
Several operating systems on 286 (eg Xenix, Coherent, OS/2) used its MMU for multitasking and memory protection. See https://en.wikipedia.org/wiki/Intel_80286#Protected_mode
1 day ago
Several operating systems on 286 (eg Xenix, Coherent, OS/2) used its MMU for multitasking and memory protection. See https://en.wikipedia.org/wiki/Intel_80286#Protected_mode
The 286 protected mode did not allow for a 32-bit flat address space and was heavily half-baked in other ways, e.g. no inbuilt way to return the CPU to real mode without a slow and fiddly CPU-reset.
It was architecturally a 16-bit CPU so a flat 32-bit address space would be a non sequitur. If you wanted flat 32-bit addressing, there was a contemporary chip that could do it with virtual memory: Motorola 68010 + the optional external MMU. (Or if you were willing to do some hoops, even a 68000.. see the Sun-1)
Coherent was the first Unix-like OS I ran, on a 386SX box. I think it was Coherent 4.x.
[dead]