High performance coprocessor boards of the 80s and 90s - was Re: SGI ONYX

Liam Proven lproven at gmail.com
Mon Apr 25 08:47:12 CDT 2016

On 22 April 2016 at 19:51, Swift Griggs <swiftgriggs at gmail.com> wrote:
> On Fri, 22 Apr 2016, Liam Proven wrote:
>> GEM ran on MS-DOS, DR's own DOS+ (a forerunner of the later DR-DOS)
> It still runs under FreeDOS, too. I've puttered around with it several
> times in that environment.

Yes indeed. In fact the first time I installed FreeDOS I was *very*
surprised to find my name in the credits. I debugged some batch files
used in installing the GEM component.

>> ... and on the Atari ST's TOS, derived in part from CP/M-68K.
> Ah ha! I always wondered about that relationship. So, the ST TOS GEM *was*
> in fact related to the same version that ran on DOS.

Oh yes. Same environment. ST GEM was derived from GEM 1; PC GEM from
GEM 2, crippled post-lawsuit. Then they diverged. FreeGEM attempted to
merge them again.

> I always wondered if it
> was just similar naming, copy-cat syndrome, or if they were a licensee.

Oh no no. Same codebase.

> Now
> I know! I never had an ST, unfortunately. I just drooled on them.

They can be quite cheap now, and the Aranym environment gives you
something of the feel of the later versions. It's not exactly an
emulator, more a sort of compatibility environment that enhances the
"emulated" machine as much as it can using modern PC hardware.


And the ST GEM OS was so modular, different 3rd parties cloned every
components, separately. Some commercially, some as FOSS. The Aranym
team basically put together a sort of "distribution" of as many FOSS
components as they could, to assemble a nearly-complete OS, then wrote
the few remaining bits to glue it together into a functional whole.

So, finally, after the death of the ST and its clones, there was an
all-FOSS OS for it. It's pretty good, too. It's called AFROS, Atari
Free OS, and it's included as part of Aranym.

I longed to see a merger of FreeGEM and Aranym, but it was never to be.

The history of GEM and TOS is complex.

Official Atari TOS+GEM evolved into TOS 4, which included the FOSS
Mint multitasking later, which isn't much like the original ROM
version of the first STs.

The underlying TOS OS is not quite like anything else.

AIUI, CP/M-68K was a real, if rarely-seen, OS.

However, it proved inadequate to support GEM, so it was discarded. A
new kernel was written using some of the tech from what was later to
become DR-DOS on the PC -- something less like CP/M and more like
MS-DOS: directories, separated with backslashes; FAT format disks;
multiple executable types, 8.3 filenames, all that stuff.

None of the command-line elements of CP/M or any DR DOS-like OS were
retained -- the kernel booted the GUI directly and there was no
command line, like on the Mac.

This is called GEMDOS and AIUI it inherits from both the CP/M-68K
heritage and from DR's x86 DOS-compatible OSes.

>> The only BBC copro that could run GEM, AFAIAA, was the BBC Master 512 with
>> the Intel 80186.
> Whoa. That sounds bizarre but cool.

It was, in a limited way.

Acorn's series of machines are not well-known in the US, AFAICT, and
that's a shame. They were technically interesting, more so IMHO than
the Apple II and III, TRS-80 series etc.

The original Acorns were 6502-based, but with good graphics and sound,
a plethora of ports, a clear separation between OS, BASIC and add-on
ROMs such as the various DOSes, etc. The BASIC was, I'd argue
strongly, *the* best 8-bit BASIC ever: named procedures, local
variables, recursion, inline assembler, etc. Also the fastest BASIC
interpreter ever, and quicker than some compiled BASICs.

Acorn built for quality, not price; the machines were aimed at the
educational market, which wasn't so price-sensitive, a model that NeXT
emulated. Home users were welcome to buy them & there was one
(unsuccessful) home model, but they were unashamedly expensive and
thus uncompromised.

The only conceptual compromise in the original BBC Micro was that
there was provision for ROM bank switching, but not RAM. The 64kB
memory map was 50:50 split ROM and RAM. You could switch ROMs, or put
RAM in their place, but not have more than 64kB. This meant that the
high-end machine had only 32kB RAM, and high-res graphics modes could
take 21kB or so, leaving little space for code -- unless it was in
ROM, of course.

The later BBC+ and BBC Master series fixed that. They also allowed ROM
cartridges, rather than bare chips inserted in sockets on the main
board, and a numeric keypad.

Acorn looked at the 16-bit machines in the mid-80s, mostly powered by
Motorola 68000s of course, and decided they weren't good enough and
that the tiny UK company could do better. So it did.

It designed the ARM chip in-house, then launched its own range of
ARM-powered machines, with an OS based on the 6502 range's. Although
limited, this is still around today and can be run natively on a
Raspberry Pi:


It's very idiosyncratic -- both the filesystem, the command line and
the default editor are totally unlike anything else. The file-listing
command is CAT, the directory separator is a full stop (i.e. a
period), while the root directory is called $. The editor is a very
odd dual-cursor thing. It's fascinating, totally unrelated to the
entire DEC/MS-DOS family and to the entire Unix family. There is
literally and exactly nothing else even slightly like it.

It was the first GUI OS to implement features that are now universal
across GUIs: anti-aliased font rendering, full-window dragging and
resizing (as opposed to an outline), and significantly, the first
graphical desktop to implement a taskbar, before NeXTstep and long
before Windows 95.

It supports USB, can access the Internet and WWW. There are free
clients for chat, email, FTP, the WWW etc. and a modest range of free
productivity tools, although most things are commercial.

But there's no proper inter-process memory protection, GUI
multitasking is cooperative, and consequently it's not amazingly
stable in use. It does support pre-emptive multitasking, but via the
text editor, bizarrely enough, and only of text-mode apps. There was
also a pre-emptive multitasking version of the desktop, but it wasn't
very compatible, didn't catch on and is not included in current

But saying all that, it's very interesting, influential,
shared-source, entirely usable today, and it runs superbly on the £25
Raspberry Pi, so there is little excuse not to try it. There's also a
FOSS emulator which can run the modern freeware version:


For users of the old hardware, there's a much more polished commercial
emulator for Windows and Mac which has its own, proprietary fork of
the OS:


There's an interesting parallel with the Amiga. Both Acorn and
Commodore had ambitious plans for a modern multitasking OS which they
both referred to as Unix-like. In both cases, the project didn't
deliver and the ground-breaking, industry-redefiningly capable
hardware was instead shipped with much less ambitious OSes, both of
which nonetheless were widely-loved and both of which still survive in
the form of multiple, actively-maintained forks, today, 30 years later
-- even though Unix in fact caught up and long surpassed these 1980s

AmigaOS, based in part on the academic research OS Tripos, has 3
modern forks: the FOSS AROS, on x86, and the proprietary MorphOS and
AmigaOS 4 on PowerPC.

Acorn RISC OS, based in part on Acorn MOS for the 8-bit BBC Micro, has
2 contemporary forks: RISC OS 5, owned by Castle Technology but
developed by RISC OS Open, shared source rather than FOSS, running on
Raspberry Pi, BeagleBoard and some other ARM boards, plus some old
hardware and RPC Emu; and RISC  OS 4, now owned by the company behind
VirtualAcorn, run by an ARM engineer who apparently made good money
selling software ARM emulators for x86 to ARM holdings.

Commodore and the Amiga are both long dead and gone, but the name
periodically changes hands and reappears on various bits of modern

Acorn is also long dead, but its scion ARM Holdings designs the
world's most popular series of CPUs, totally dominates the handheld
sector, and outsells Intel, AMD & all other x86 vendors put together
something like tenfold.

Funny how things turn out.

Liam Proven • Profile: http://lproven.livejournal.com/profile
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