Post #983117
2026-01-28 23:29 UTC
today at the Computer History Museum we adjusted the read timings on the 1401 computer's 1402 card reader. to do this, we load a deck of "555" timing cards, which have the number 5 punched in columns 1-3 and 78-80. seems that 555 really is a magic number for timers...
Replies (3)
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@tubetime@mastodon.social 2026-01-28 23:33
on the side of the 1402, normally covered by the grey side panels, is the customer engineering panel. it includes a dynamic timing analyzer--a gauge marked out in degrees that uses two spinning neon bulbs to indicate either cam timings or brush timings. we can check the holes punched in the 555 card to make sure they are arriving at the correct angle.
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@wikinaut@berlin.social 2026-01-29 00:36
@tubetime 555 https://youtu.be/mDhNQPt8An0
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@literatesavant@mastodon.au 2026-01-29 09:20
@tubetime I wonder how long the original designers of these machines imagined they would last. Surely not 60 years!