The Torch Unicorn - a Unix for Acorn

From 1984, a third-party second processor for the BBC Micro, with a 68000 and running a Unix (System III):

Photo from this review in Acorn User.

There’s a Z80 in there too, to run CPN and to boot the (8MHz) 68000. And with a 20MB hard drive and 256k RAM or more, you won’t be surprised to hear it cost £3000 in basic configuration.

When the Acorn 16032 second processor comes out, ostensibly providing Xenix at around the £1000 mark, Unicorn will no longer be the cheapest [route to Unix].

As the hard drive was connected to the 8-bit host, I/O was not fast:

The power of Unix carries a cost, in terms of memory requirements and speed, that the Unicorn is barely capable of meeting.

And don’t hit the prominent Break key, as the machine takes 4 minutes to boot, and the filesystem might even be corrupted.

As an interesting note, the Torch second processors do use the Tube connector to the Beeb, but merely as a 2MHz peripheral bus: they use a 6522 to talk to their subsystem, not a Tube chip.

A note from the review about the future:

Now [Unix] is becoming available on microcomputers. In ten years’ time, the megabyte micros we all hope to have will almost certainly provide Unix or a descendant of it.

Here’s a brochure with some technical information:

More here, of course:


There’s currently a Torch Unicorn resurrection thread on stardot:
Torch Unicorn SASI card

It’s this system:
Ex TORCH employee with old Communicator & Unicorn

I do understand that Torch Computers came from the 6502 side of things, meaning, this is probably the ultimate expansion to any 6502 system. However, I fail to understand this as a product. I guess, interfacing with the Beeb and writing the control software offsets any savings on I/O on the Unix side pretty much, but adds a lot of complexity. The choice of AT&T UNIX (as opposed to Xenix, e.g., this means, you had to licence any developer tools as an extra) probably doesn’t help making this a budget system, either. (On the plus side, you could probably run additional Beebs as cheap and smart color terminals via Econet, quite a unique proposition.) — That said, this is really impressive!

BTW, “Torch Unicorn” sounds much like a project, the US defense/intelligence sector would come up with. :wink:

Yes, I think I’d say impressive but misguided. Maybe they realised too late that the 8 bit host was going to be a massive bottleneck. Looks like the Triple X, their follow-on, was more conventionally architected. Wikipedia leads us to this late '95 statement, though: “The Torch Unicorn, an earlier UNIX-based PC model launched in early 1984, is now the UK’s best UNIX seller.”

The triple X was a fairly normal Unix system. One used to run one of the gateways at University of Wales Aberystwyth when I was a student there.

The combo CPU set up was also not that uncommon back then - eg the Cifer 68K systems Swansea Uni Business School had were 68K with a Z80 as I/O processor and able to run CP/M on the IOP instead if needed.

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