3 ms·

It's a cool idea, but wouldn't every program have full access to all of memory? The m68000 had no memory protection and could technically run an operating syst

It's a cool idea, but wouldn't every program have full access to all of memory? The m68000 had no memory protection and could technically run an operating system, but it came with the implied request that no program overwrite the operating system's working RAM.

phoe-krk 6y ago
I don't think that full access to all memory and SUBLEQ architecture must happen at the same time. For instance, you can already run a 100% ring-0 operating system on top of x86_64 (e.g. DOS, TempleOS, Mezzano), but it should also be possible to equip a SUBLEQ CPU with some kind of programmable MMU with memory protection that will cause segfaults to happen when invalid addresses are accessed. (And then you'll need syscalls to actually jump to the proper ring and access that memory, and such stuff, which might go against the political agenda of DawnOS.)
fogihujy 6y ago
That was one of the more common causes of crashes back in the AmigaOS days; one program crashed and while doing so it screwed up the OS and other running applications as well. It worked quite well as long as your applications were well-behaved though.
- hyakosm 6y ago
  The Amiga had a preemptive operating system, but because of the lack of memory protection Linus Torvalds called it "pseudo-preemptive" and considered it equivalent as cooperative. https://en.wikipedia.org/wiki/Exec_(Amiga)#cite_note-Torvalds-4 https://en.wikipedia.org/wiki/Exec_(Amiga)#cite_note-Torvald...
  - fogihujy 6y ago
    Stability-wise, definitely -- a single misbehaving piece of code could do whatever it wanted as nothing prevented an application from taking over completely (or more commonly, just crash the entire computer) When doing it with well-behaved applications, on the other hand, AmigaOS was multi-tasking on a whole other level compared to contemporary operating systems using actual cooperative multitasking. It was a neat little OS. Fast as hell and with several little features that I still find myself missing from modern OS'es. Too bad Commodore screwed up.

phoe-krk 6y ago

I don't think that full access to all memory and SUBLEQ architecture must happen at the same time. For instance, you can already run a 100% ring-0 operating system on top of x86_64 (e.g. DOS, TempleOS, Mezzano), but it should also be possible to equip a SUBLEQ CPU with some kind of programmable MMU with memory protection that will cause segfaults to happen when invalid addresses are accessed. (And then you'll need syscalls to actually jump to the proper ring and access that memory, and such stuff, which might go against the political agenda of DawnOS.)

fogihujy 6y ago

That was one of the more common causes of crashes back in the AmigaOS days; one program crashed and while doing so it screwed up the OS and other running applications as well. It worked quite well as long as your applications were well-behaved though.

hyakosm 6y ago
The Amiga had a preemptive operating system, but because of the lack of memory protection Linus Torvalds called it "pseudo-preemptive" and considered it equivalent as cooperative. https://en.wikipedia.org/wiki/Exec_(Amiga)#cite_note-Torvalds-4 https://en.wikipedia.org/wiki/Exec_(Amiga)#cite_note-Torvald...
- fogihujy 6y ago
  Stability-wise, definitely -- a single misbehaving piece of code could do whatever it wanted as nothing prevented an application from taking over completely (or more commonly, just crash the entire computer) When doing it with well-behaved applications, on the other hand, AmigaOS was multi-tasking on a whole other level compared to contemporary operating systems using actual cooperative multitasking. It was a neat little OS. Fast as hell and with several little features that I still find myself missing from modern OS'es. Too bad Commodore screwed up.