PDP-8 chase the lights

Mike Ross tmfdmike at gmail.com
Tue Feb 2 19:34:56 CST 2016

Nicely done! I don't think I've seen that one before; can you supply a
quick toggle in?


On Wed, Feb 3, 2016 at 9:26 AM, Evan Koblentz <cctalk at snarc.net> wrote:
> Our group here in NJ + surroundings now has monthly-ish repair workshops
> (vs. a few times per year before). At the workshop this past weekend, David
> Gesswein continued restoring our PDP-8.
> David summarized: "I fixed the known fault of accumulator bit
> going to zero when it was rotated left. This was a bad diode on one
> of the accumulator boards. I also replaced two bad bulbs and a third
> that died during the repair. Since one that died was one I previously
> replaced I'm going to use the not quite matching bulbs with heavier
> wires for future repairs. The wires are just too thinn on the 1762 bulbs
> and now that they have aged they break too easy. I then found that the
> teletype interface wasn't working and replaced a diode on a R220 to fix
> output. Input is not working properly. I have traced it to a particular flip
> flop on a R220 where when the data changes it feeds through to the output
> without the clock active. I ran out of time to identify the component that
> needs replacing."
> Here's a little video of the computer chasing its lights. :)
> http://www.vcfed.org/evan/pdp8lights.mp4


'No greater love hath a man than he lay down his life for his brother.
Not for millions, not for glory, not for fame.
For one person, in the dark, where no one will ever know or see.'

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