A tale of woe, including carelessness, stupidity and laziness....

Eric Smith spacewar at gmail.com
Sat Aug 22 16:11:16 CDT 2015

On Sat, Aug 22, 2015 at 1:41 PM, Jay Jaeger <cube1 at charter.net> wrote:
> But the carelessness was DANGEROUS, which is really why I posted it.
> (BTW, in the way of other stories, a good friend once took out the
> processor UNIBUS interface and damaged peripherals when his watch
> shorted to the backplane of a PDP-11/20.  I also did something not too
> dissimilar with my ring shorting out one bus line on my PDP-8/L.  Sigh).

In my mostly misspent youth, I once had the opportunity to visit a
facility where a now obscure supercomputer was developed. The product
manager was showing me around. At one point we were looking at the
backplane of a machine being tested or debugged, and an engineer comes
over and starts to do something with the backplane, and the manager
grabs his hand. He tells the engineer that he shouldn't work on it
with a gold ring on his finger. At first I thought the manager was
worried about the possibility of damage to the machine, but he quickly
explained that he wasn't much worried about that, but rather for
employee safety.

The engineer said that it wasn't a problem because the highest voltage
on the backplane is 5V. The manager pointed out that the power supply
was rated for 600A, and undoubtedly could source more than that
briefly, and to think about what would happen to your finger if you
had hundreds of amps flowing through the ring.

I suppose that might not be quite as exciting as having your neck tie
caught in a 1403, but it still could make for a really bad day.

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