[TUHS] ATT Hardware

John P. Linderman jpl.jpl at gmail.com
Sat Jun 30 00:55:48 AEST 2018

You just pushed my "3B button". Rudd Canaday (who had a hand in the design
of the original UNIX file system) wanted to create a message-based
"Database Machine". We planned to base it on the MERT (Multi-Environment
Real Time) UNIX variant on VAXen, and had some of the architects of MERT on
the team with real expertise in VAX architecture. Unfortunately, just as we
were getting under way, the AT&T chip project needed clients, so we were
told "Thou shalt use AT&T computers".  Not only did we have no expertise,
the documentation was almost non-existent, so the only way to learn was
trial and error. They installed two 3B20-ish computers that looked like
racks of telephone equipment (because that's pretty much what the were).
The first time we lost power in the computer room, and tried to bring
it/them back up, all the fuses blew. The AT&T techs looked astonished, and
asked if we lost power often (in a switching office, battery backups
ensured that power was never lost). We told them power went down every few
months. They showed us how to power things up by removing all the fuses,
then using a charging device (we called it the fuse-gooser) to charge up a
capacitor, insert a fuse, and repeat until all the fuses had been
reinstalled. Eventually, one of our people discovered an (undocumented, of
course) dial which could be used to ramp the voltage up from 0 to full, so
we didn't have to go through the fuse routine. "Production" versions of the
3B20's had a lead-acid battery built in.

There was no floating point. (Why would a switch need floating point?).
There were things I wanted to do with awk that didn't need floating point,
so I just fiddled the code so AWKFLOAT was typedef-ed to int, and it darn
near worked. The only hitch was a couple of appearances of "%g" in print
statements. I couldn't typedef them away, but I suggested to the ANSI C
folks that I could have done that if the appearance of adjacent string
literals was treated as their concatenation, and they bought it. My only
contribution to ANSI C, courtesy of crappy hardware.

We were also gifted a 3B2. We brought it up single user, and it took 20
seconds to run a ps command. Our computers were theme-named after birds
(the 3B20 pair were heckle and jeckle), so we named the 3B2 junco. Our
director told us we couldn't do that, we had to play nice with the chip
folks. So we renamed it jay. But we all knew what the j stood for.

On Fri, Jun 29, 2018 at 9:16 AM, <ron at ronnatalie.com> wrote:

> The recent reference to the Dennis’s comments on ATT chip production had
> me feeling nostalgic to the 3B line of computers.  In the late 80’s I was
> in charge of all the UNIX systems (among other things) at the state
> university system in New Jersey.   As a result we got a lot of this
> hardware gifted to us.    The 3B5 and 3B2s were pretty doggy compared with
> the stuff on the market then.   The best thing I could say about the 3B5 is
> that it stood up well to having many gallons of water dumped on it (that’s
> another story, Rutgers had the computer center under a seven story building
> and it still had a leaky roof).    The 3B20 was another thing.   It was a
> work of telephone company art.    You knew this when it came to power it
> down where you turned a knob inside the rack and held a button down until
> it clicked off.    This is pretty akin to how you’d do things on classic
> phone equipment (for instance, the same procedure is used to loopback the
> old 303 “broadband” 50K modems that the Arpanet/Milnet was built out
> of).    Of course, the 3B20 was built as phone equipment.    It just got
> sort of “recycled” as a GP computer.
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