🚀 go-pugleaf

PDP/10 (aka DECSystem 10) war story.  This was told to me by a DEC service
engineer many moons ago (1971 or so).  It's probably apocryphal, but so
what?

The 10 used as a swapping disk a really big (27") head per track disk from
Borroughs that rotated vertically instead of horizontally.  It was so
sensitive they kept it isolated behind a fence.  It seems that one day at
the old woolen mill all of the PDP/10 swapping disks on test began
crashing at exactly the same time.  Every day, the clock would chime 3:30
and all the disks would snap their heads back.  Engineers descended on the
test area.  The dragged out every oscilloscope they could find.  They
monitored the power supplies, they monitored the building power, they
checked for magnetic fields, everything.  Nothing worked.  Every day, 3:30
bang all disks down.  One day at 3:25 one of the engineers who could no
longer bear the sight of the crashes went downstairs to the loading dock
for a cigarette.  At 3:30 right on the button a big truck rolled down the
ramp and crashed, kerbang, right into the dock, shaking the building and
crashing all the disks.  They rotated all the disks 90deg and the problem
went away.