21 Apr
2016
21 Apr
'16
11:47 a.m.
On Apr 21, 2016, at 2:04 PM, Rick Bensene <rickb at
bensene.com> wrote:
...
The machine was an all-transistor design, based on the CDC 6600
processor. It was liquid cooled, and had a large cooler unit that sat
with the machine that cooled the coolant (water) and circulated it
through the chassis, venting the heat (which was substantial) through a
special venting system. I remember the CDC Field guys talking about
horror stories when there were leaks in the cooling system. We never
had any problems while I was there.
Rick,
Nice memories, thanks for posting that. I don't think there are any Cyber 70 (CDC
6000 series) systems still running, but there's one in emulation, running PLATO. See
cyber1.org. It even has emulated console tubes...
The machine itself was cooled with Freon (the non-PC flavor). The chilled water
you're referring to would take heat away from the Freon cooling system compressors (at
the end of each of the CPU cabinets).
One day I was at the console when one of the big
high-voltage rectifier
tubes that were in the console decided to short.
I was watching one of the system monitor displays, and suddenly I saw
the display collapse into a single very bright horizontal line. I noted
that the other display also did the same thing. I also heard a funny
noise that sounded kind of scary, so I started to push my wheeled chair
away from the console, but not soon enough to avoid a shower of sparks
and even some molten metal that spewed out from the console.
Yikes. I think the rectifiers were solid state. But the deflection amplifiers used high
power triodes (3CX100A5) as the final amplifier stage, running around 3 kV anode voltage.
If something goes wrong with those, sparks would definitely be a possibility. And
you'd expect to see a line (horizontal or vertical).
paul