68010 / 68451 MMU Homebrew

Description

the 68451 MMU was made as a companion for the 68010 CPU, Motorola's first CPU to support virtual memory. There are very few examples of machines built with this combination, and neither Linux nor NetBSD support it (yet). Most 68010 machines were either built with no MMU at all (being a minor upgrade from the 68000), custom MMU's (for instance the Sun-2), or the generation was skipped entirely for later M68k CPU's that included on-chip MMU.

Files

68451_Memory_Management_Unit.pdf

Manual for the 68451

Adobe Portable Document Format - 2.40 MB - 11/05/2020 at 23:58

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John Sonnenschein • 03/01/2020 at 21:40 • 0 comments

I've found exactly one example of schematics of a machine that used the 451 at https://archive.org/details/bitsavers_compuproA1nualNov83_1763479/page/n7/mode/2up

Unisoft was a company in the 80's that ran around porting UNIX to various things, and they have a version of UTSv7 on bitsavers: http://bitsavers.org/bits/Unisoft/V.1.5+/sys/

and finally, the retrobrew community has peripheral boards and compute boards that use the 68000. Presumably we can shoehorn the 68010 in to there (it was pin compatible) with the 451 in between https://www.retrobrewcomputers.org/doku.php?id=boards:ecb:mini-68k:start

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ramon_blake wrote 04/28/2024 at 21:00

Thank you for the information. I would like to try this one day

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Watchm4ker wrote 04/12/2020 at 09:07

I've poked at this idea myself, ever since I saw the MMU. From what I can tell, between the 68000's botched page fault handling, and the limited capabilities of the 68451, most system designers used their own MMUs. That S-100 card's a good find, though I had a thought of using VMEBus. After all, it was designed for backplane 68000 machines from the start.

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RW wrote 03/01/2020 at 22:17

Hi John, there's some documents in the hardware directory on Aminet that cover swapping their 68000s over to 68010s, so you may find them of use when using an 010 in an 000 design.

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68010 / 68451 MMU Homebrew

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Description

Files

68451_Memory_Management_Unit.pdf

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