PDP11's TU10's and Write rings

From: Bill Pechter <pechter_at_pechter.dyndns.org>
Date: Sun Apr 11 12:41:57 1999

> >Bill Pechter wrote:
>
> > (One day, ask me about the DEC story of the customer who epoxied in the write
> > ring area on the 9 track tapes to make sure his operators couldn't put
> > them in to write enable and over-write a backup tape...)
>
> Jerome Fine replies:
>
> OK! I bite. This is "One day". But two questions:
>
> Was the backup already made? Or did the customer try and "anticipate"
> the problem by putting in the epoxy before the backup was done?

I seem to remember this story something like this.

This was told to me by another Field Service grunt... so it's basically
a friend of a friend tale -- and I can't verify it... but I believe it all.

There was this small automotive house that was just going to computers for
their inventory instead of the manual punch card tub used for stock pulls
at the time.

They had a problem with their backups (I believe it was an 11 running
RSTS or RSX). The tech went down and found there was an ECO to the tape
drive write gate or write amp circuit, fixed it and talked with the shop
owner who was very afraid of losing more backup data).

The tech sat down and explained the tape had this wring at the back
and even if the operator issued the commands reversing input and output
with this special plastic ring removed the drive couldn't overwrite.
the tape.

The shop owner was very pleased and told the tech and the service manager
about it and all was well for a couple of weeks...

They tried to recover data from a backup tape that was overwritten.
The tech went down, tested the drive and pronounced it ok.
The write lock solenoid was good, the write gate logic was working.
There was NO WAY the operators could've overwritten the tape with the
ring removed.

The owner showed the tech a box where all the write rings were removed and
stored and one ring was left locked away in case they needed to write
on a tape.

The owner said I even guaraneed these rings will never go in our backup
tapes again.

The tech looked at the tape. The write ring space was filled smooth with
fast drying epoxy or body filler.

The tech had a hard time not laughing and explained how the write lock
solenoid and write ring worked.

Bill
Received on Sun Apr 11 1999 - 12:41:57 BST