Metacomco / Commodore Amiga Transputer Board

Subject: Re[2]: Amiga Transputer query
Date: Wed, 8 Jul 1998 23:25:33 -0400 (EDT)

The Transputer was certainly interesting. INMOS (the parent company at
the time, the same guys making the original RAMDAC used for the IBM VGA
card) seemed to want to make Transputers work essentially as front ends
to every piece of your system. Rather than talk talk to a hard disc,
you'd talk to a Transputer fronting the hard disc. Same with video and
other I/O.

So conceptually, the processor could be used like an embedded CPU. It
had about 4K of on-chip RAM (not cache), a built-in RAM controller (
glueless, just add DRAM), and it could boot from a network link (so, in
theory anyway, you only had to boot one Transputer in a network by
conventional means). You generally programmed Transputers using Occam, a
language designed specifically for/with the Transputer. Occam supported
thread-style tasks (the Transputer had no MMU, thus no heavy-weight
tasks) in the language, and used FIFOs/Pipes for communication, so you
wrote code the same way, regardless of whether you were talking to tasks
on the same Transputer or one over a link. It was an interesting
approach to loosely coupled multiprocessing.

The chink in the armor was the price. You paid around $400 for a T800,
when the 68030, at nearly the same performance (based on our benchmarks),
cost under $100 in quantity. So Transputers didn't function, in practice,
the way they were designed to work. At $10-$25, it would have been
practical to build a system with several, working as specified, fronting
I/O subsystems and all. The other problems were in software. Without
memory protection, it wasn't going to fly as a high-end system. The
Helios OS had a UNIX-like look, but it wasn't UNIX. Loosely coupled
multiprocessing isn't as general purpose as tightly coupled multiprocessing,
since the communications overhead is high, and thus best suited for
problems that can be broken up into lots of separate chunks. A company
called Meiko sold a Transputer array for graphics rendering, at least
back then (the Meiko Computing Surface), which was pricey, but no less
reasonable than an 8000 node iCOMP from Intel. For our work, it didn't
fly.

> I believe at
> this point Tim went on to sell the concept to Atari, where it became the
> Atari Transputer.

Atari hooked up with the Perihelion guys, who had developed the system
that eventually became the Atari Abaca. Basically, they were graphic chip
guys (some of the same folks made the Atari Jaguar, and now work at VM
Labs), but in an effort, I suppose, to do something different, they
went for the Transputer. Needing an OS, they turned to Tim and the Boys,
with Atari doing the usual "here's some money, we can sell this" song
and dance. I hear they made a few hundred Abacas.