3 ms·
> I think the MMU was introduced with the 68020 Apparently it was possible to use MMU even with 68000. A few months back someone on HN was describing on how th
by jagrsw 3y ago
> I think the MMU was introduced with the 68020
Apparently it was possible to use MMU even with 68000. A few months back someone on HN was describing on how they implemented it, even if 68000 wasn't designed for it (?) -
From: https://news.ycombinator.com/item?id=34762508 https://news.ycombinator.com/item?id=34762508
"The Sun-1 workstation used a Motorola 68000 CPU at 10MHz. This was paired with an in-house designed MMU. It had 256K zero wait state memory with parity, and 32K EPROM memory."
- pinewurst 3y agoThe Sun-1 MMU was a base/bounds swapping MMU, not a VM paging MMU. The Sun-2 and Sun-3 had the full monty VM MMUs.
- cjsplat 3y agoNope. The Sun-1 MMU was segment and page registers indexed hierarchically off the physical addresses. It was a full page based system with segment and page level sharing and protection. The 68000 didn't support restart from page faults, so the runtime model was indeed segment level swapping. (Note - not what Linux decided to call swapping)
- snvzz 3y ago68010 solved this, with a new stack frame format for page faults that had enough information to resume. Most of these early m68k UNIX boxes used the 68010 for that reason. Besides the tight loop optimization, the other 68010 changes, like move from SR being privileged (new from CCP unprivileged) are bugfixes.