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

Liam Proven lproven at gmail.com
Mon Apr 25 10:02:46 CDT 2016

On 25 April 2016 at 15:47, Liam Proven <lproven at gmail.com> wrote:
> 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.

I meant to develop this point slightly, and did in a blog post, here:


But in the meantime, it kept the 6502-based, resolutely-8-bit BBC
Micro line alive with updates and new models, including ROM-based
terminals and machines with a range of built-in coprocessors: faster
6502-family chips for power users, Z80s for CP/M, Intel's 80186 for
kinda-sorta PC compatibility, the NatSemi 32016 with PANOS for
ill-defined scientific computing, and finally, an ARM copro before the
new ARM-based machines were ready.

I tweeted the blog post and it emerges that a friend of mine was an
Acorn engineer, which I didn't know, and was involved in a machine
that I mention in passing there, but was actually far more

What I dismissed as one of the ROM-based terminals was the Acorn
Communicator, a single-box machine (i.e. main board in the keyboard,
like an Amiga 500 or original 520 ST.)

This, remarkably, ran a 65816, as used in the Apple ][GS (tragically
underclocked to just 2.8MHz so as not to outperform the Mac) and the
SuperCPU cartridge for the C64.

It was Acorn's only ever native 16-bit machine -- as it made the leap
directly from 8-bit to full 32-bit -- and has ports of the 8-bit OS,
word-processor, terminal emulator and more, all in ROM.

I never previously realised.



I had previously thought it was essentially the Acorn ABC Personal
Assistant in a different case.


The Communicator is a *far* more interesting beast, with no 6502 or
copro -- it's a native 16-bit machine in the BBC family. Remarkable.

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