4 ms·
68451 or a custom SUN-like (SRAM, kind of like a PDP11) MMU, there was a guy who went around Silicon Valley in the mid 80s designing SUN-like MMUs for companies
by Taniwha 7mo ago
68451 or a custom SUN-like (SRAM, kind of like a PDP11) MMU, there was a guy who went around Silicon Valley in the mid 80s designing SUN-like MMUs for companies, they were all different, and some were broken (couldn't protect user space from kernel space).
68000s however had a problem: they couldn't return correctly from a page (MMU) fault (68010s fixed that) for a pre-VM (pre BSD or SVR2) UNIX world - however you could get around this with a few smarts
- actionfromafar 7mo agoI think someone worked around it by running two 68000 in lock-step, or-one-step-behind or something like that.
- Taniwha 7mo agoyeah, that's rather a pain though and it effectively leaves one 68k frozen while the other services the page fault - it means you can't run another user process while the page is being read in (because it too might cause a page fault)