15 Sep
2020
15 Sep
'20
11:28 p.m.
I have an MVME121 that I’d like to run some stuff on. I’m planning what I’ll need to do to
port MINIX 1.5 but since this has a 68451 segmented MMU, I’d like to actually make use of
it.
Have any historical sources been published for UNIX on the various 68010 + 68451 systems
from the early-mid 1980s? I’m curious how they used segmented MMUs.
I figure at minimum I could have several segments set up to enforce protections and a
stable per-process address space, but it’d be good to have an example.
— Chris
15 Sep
15 Sep
11:55 p.m.
Hello!
Chris I have one of the later ones, a 133 in fact, and I've been
trying to find what I could run on it. Never mind a case for it, plus
power supply and stuff.... Can you share, off list of course, where
you'd gotten it?
-----
Gregg C Levine gregg.drwho8(a)gmail.com
"This signature fought the Time Wars, time and again."
On Tue, Sep 15, 2020 at 7:49 PM Chris Hanson <cmhanson(a)eschatologist.net> wrote:
I have an MVME121 that I’d like to run some stuff on. I’m planning what I’ll need to do
to port MINIX 1.5 but since this has a 68451 segmented MMU, I’d like to actually make use
of it.
Have any historical sources been published for UNIX on the various 68010 + 68451 systems
from the early-mid 1980s? I’m curious how they used segmented MMUs.
I figure at minimum I could have several segments set up to enforce protections and a
stable per-process address space, but it’d be good to have an example.
— Chris
16 Sep
16 Sep
3:05 a.m.
On Sep 15, 2020, at 4:55 PM, Gregg Levine <gregg.drwho8(a)gmail.com> wrote:
Chris I have one of the later ones, a 133 in fact, and
I've been
trying to find what I could run on it. Never mind a case for it, plus
power supply and stuff.... Can you share, off list of course, where
you'd gotten it?
Oh, I don’t mind sharing on-list! I just bought the board—and a system controller, and
some additional RAM boards, as well as the VME chassis with built-in PSU—on eBay. Lots of
sellers are willing to make pretty good deals. There’s barely anything I paid over US$100
for, and I’ve only been collecting the VME stuff for a couple years.
In theory you should be able to use any VME or VXI chassis for most VME hardware. What’s
hard to find are manuals for anything not on Bitsavers[1], or software to run on it. At
least NetBSD has been ported to the common 68030+ and PowerPC VME boards, and an old
version of OpenBSD runs on the common 88K ones. Alas the 133 doesn’t have an MMU so it’s
going to be a bit more restricted.
One of the reasons to run MINIX 1.5 on my MVME121 is that it should be nice and fast on a
10MHz system with 8.5MB of RAM (including 4KB of cache), and as a V7 UNIX clone with an
ANSI C compiler it’ll be easy to write for and port to. It’ll probably also be nicer than
running one of the first few versions of Motorola System V/68 on it too, since I think
that’s SVR1…
Your 133 should also be straightforward to port MINIX to as well, since all the hardware’s
simple, standard, and documented in the manual (plus data books).
My plan was to start with MINIX 1.5 on Atari ST under Hatari, then just write some device
drivers and a boot loader to replace the ST-specific ones.
— Chris
[1] Or Artisan Technology Group’s web site; they sell a ton of used VME hardware, and seem
to collect what manuals and data sheets they can and provide them as PDF.
5:21 a.m.
On Tue, Sep 15, 2020 at 04:28:36PM -0700, Chris Hanson wrote:
I have an MVME121 that I’d like to run some stuff on.
I’m planning what I’ll
need to do to port MINIX 1.5 but since this has a 68451 segmented MMU, I’d
like to actually make use of it.
Quite doable to adapt MINIX to this. Did a similar thing ages ago while
still in school on a 68010 machine (not really VME, but similar card-cage
setup) that had a custom MMU built from some SRAM and some control logic on
it. Used MINIX 1.1 at the time though..
Only had 1MB physical RAM and the MMU could provide a virtual address space
of 4MB.
Initially ported MINIX to the machine 'as is' from the ST version and then
modified the MINIX kernel to allow it to use the 4MB virtual space and
such.
Because of the bare-bones MMU design it had some interesting quirks that made
it a good learning experience at the time. (and some very odd serial chips
for the terminals that had their own 'interesting' behaviour but that's
a different story..)
Originally the machine did have a real SVR2 UNIX running on it, but sadly it
was binary-only, so apart from some dis-assembly of bootstrap bits to learn
how to get MINIX to start on this machine it was not very useful.
I figure at minimum I could have several segments set
up to enforce
protections and a stable per-process address space, but it’d be good to
have an example.
Yup. You may run into some of the shortcuts in the MINIX kernel when you start
doing MMU work though, especially if you want to separate the kernel
'processes' as well.
For performance the microkernel architecture of MINIX was violated in a few
spots, mostly around FS and MM, where one kernel process would/could modify
another's memory without going through the message passing mechanism.
Introduce an MMU and that kinda breaks and needs some cleaning up ;)
As MINIX later on did get a 386 port and cleanups/fixes that may now be a
non-issue on 1.5.
Another option would be Linux/m68k and perhaps starting on the 'nommu'
version that runs on basic 68000's too and seeing how much functionality could
be used from the 68451 to enhance it.
Some of the Coldfire CPU's have similar limited MMU's that are supported for
some functions of basic memory protection in the 'nommu' tree.
As far as real UNIX sources go.. SUN2's were 68010's too although AFAIK
with a custom SUN designed MMU logic? Perhaps some old sources available in
that corner though.
Bye, Arno.
8:53 a.m.
On 9/15/20 4:28 PM, Chris Hanson wrote:
Have any historical sources been published for UNIX on
the various 68010 + 68451 systems from the early-mid 1980s?
I have been looking for these for a long time now, in particular the sources for Unisoft
Uniplus+ for the 000 or 010
and 451 MMU, or a copy of Motorola's System V port for the VME10. A very long time
ago, I disassembled the Unisoft
binary for the Uniplus+ kernel.
11:47 p.m.
On Wed, 16 Sep 2020, Al Kossow wrote:
I have been looking for these for a long time now, in
particular the sources
for Unisoft Uniplus+ for the 000 or 010 [...]
I still have the mental scars from having to support Uniplus+ ... Please
don't ask for further details, because I don't want to recall them when
having to demonstrate an unstable system at a pre-sales demo.
-- Dave
1322
days inactive
1323
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5 comments
5 participants
participants (5)
-
Al Kossow -
Arno Griffioen -
Chris Hanson -
Dave Horsfall -
Gregg Levine