[inforoots] SAGE Experience Reports

[John Whetzal]

Hi,
 
I was a maintainer on the Q-7 at Duluth AFB, 1973-1982.
 
Scheduled maintenance, known as Preventive Maintenance Inspections
(PMIs) were rotated each day...i.e. "A" computer on Monday, "B" computer
on Tuesday, "A" computer on Wednesday and so on.  PMIs were divided into
daily, weekly (7 day), monthly (28 day), quarterly (68 day), semi-annual
(156 day), and annual (336 day).  Each day when we came to work, there
was a computer generated list of the PMIs we had to perform that day.
PMIs and maintenance were mostly done on swing and mid-shifts.  We also
did "reinsertions" which was inserting previously failed pluggable units
(PUs) into the off-line machine and running the applicable maintenance
program to determine if they were properly repaired by the personnel in
the PU lab.  I worked in the PU lab for a while. In the early 1970's we
did just replace all the tubes in the pluggable unit.  Each PU had the
capacity to hold 8 tubes-depended on the number of circuits/circuit
cards in the PU.  I remember 7236s tubes which I believe were line
drivers for the core memory & 6888s were also a common tube.
 
I believe we had 40+ computer maintainers assigned to our system.
 
Whether the computer was "down" during maintenance, depended on what
PMIs you were performing & how quickly you could restore the system.  If
you were changing a drum belt, you could not come back up as fast as
changing a tube in central computer.
 
I worked mostly in Input/Output...IBM 728 tape drives, line printers,
card readers, card punches, LRI & XTL and in Outputs--frames 33 & 42?,
Tape drive power was unit 18.  I remember the maintenance program names:
XTL Overall, LRI Overall, MC1L (marginal checking on frame 13-tape
adapter) & Tapes1B on tape drives, Outputs Overall, Big Mem & LiL Mem.
This is straining my brain to recall this stuff.
 
I remember if 6HD V8 went bad the computer would simultaneously select
main & aux drums.  I remember the whining of those drums.  I have
ringing in my ears and no doubt listening to those drums 8 & 12 hours a
day for 9 years contributed.
 
In 1981 when the Duluth computer was shut down, we removed all the tubes
and individually wrapped them in a small piece of cardboard and secured
the cardboard with a rubber band.  We then stacked the tubes into large
boxes and sent them to IBM, who was the depot for Q-7 parts.
 
 
Thanks,
 
John Whetzal
 
 
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