PDP-9 lives again....

From: Hans B Pufal <hansp_at_aconit.org>
Date: Fri Aug 30 14:19:43 2002

Some 20 odd years after it was decommisioned we finally got our PDP-9 to
boot software off an old DECTape. Advanced Software System version 5A
came up today for the first time on our restored -9.

This after a long and frustrating summer when we spent over 100 man
hours chasing a processor fault which resulted in the execution of the
saved PC value after an interrupt (instead of the word after the saved
PC value). Turned out to be a misaligned delay circuit which caused a
reset signal to arrive late and provoke all sorts of havoc in the
processor while nicely reseting all the tell-tales.

Seems like the memory and processor hardware is quite stable now. We
have two DECtape units attached with two more units availabe to be
attached. Further debug on the DECtapes and learning the software will
be followed by attachemnt of TU20 mag tape units.

If anyone knows of an available (and cheap) large X-Y plotting scope
preferably somewhere in europe we would be very interested in hearing
from you. We have a graphics controller but no large screen. With the
screen, the DECtapes and the TU20's this is going to be one impressive

We also used the -9 for the first time today to try and recover an image
from an old Elliott 903 paper tape I was given in the UK recently. Due
to operator error that attempt failed but I fully expect to be able to
get a tape image this weekend.

  -- hbp
Received on Fri Aug 30 2002 - 14:19:43 BST

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