Funny you should mention degaussing. A long time ago at work, we had
some really nice HP or Digital (I don't recall for certain) CAD
workstations with high-end CRT monitors. One of the buttons on the front
of it was a Degauss button. Some of the work cubicles were back to back,
and if engineer Bob degaussed his monitor, it would send color flashes
across engineer Fred's monitor on the other side of the wall. Well,
engineer Fred had a serial port extension under the front of his monitor
that he kept his CAD key in (early version of MicroCADAM, IIRC), so to
pay Bob back for interrupting his work (nap time), he hit his degauss
button 3 or 4 times in rapid succession. Later, when he tried to get
into CAD, he got a "No key found" error. He called me to fix it, and
showed me the key was plugged in, but couldn't be read. Seems the
degaussing had corrupted the EEPROM enough that it couldn't be read any
more. Luckily, as admin, I had the program to reprogram it, so all ended
well. But an email was sent out warning every one of the inherent
dangers of keeping anything electronic next to the monitors when
degaussing. There was a story of a digital watch, but I never saw it, so
I can't confirm the truth of it.
I knew about degaussing probably over half a century ago. IMB had ferric
oxide coated plastic rolls, much the same as the tape used in reel to
reel tape recorders but in the shape of a cylinder which were used over
two 1" rollers which a lever would move further apart from one another
thus providing a taut fit for the magnetic cylindrical belt which could
then be used much the same as a reel to reel machine. The fact that you
could move the head on the playback machine at will gave instant access
to any part of the recording which was a great plus point over reel to
reel tape recorders. The recording head moved helically much like on
some LP players with straight arms which gradually moved towards the
center of the LP being played.
I don't really know how widespread the use of these IBM machines were
but I would have thought they would have been in great demand by big
corporations for dictation purposes. In fact the playback machines were
specifically designed for such use as releasing the foot pedal stopped
the playback and the head moved back a couple of seconds or so for
continuity for the benefit of the typists. At the time I worked in a
news outfit. The job was demanding but interesting and the pay was good.
Though it meant goodbye to all the holidays I had enjoyed as a teacher.
These cylindrical magnetic rolls would every now and then be collected
by the engineers who would degauss them so they could be used again and
again. And the degaussing machine made a noise much like a gun being
fired when the button was pressed to instantly degauss the belts --
around 20 or more all within one another.
Before the advent of magnetic belts, they used plastic belts for this
purpose but of course these belts could only be used once and then had
to be discarded, unless of course they were kept for archiving purposes.
Earlier models of these machines used plastic belts cutting a groove in
the plastic belts much like machines on which sounds were recorded on
blank LPs. The machine literally cuts grooves in the blank plastic LP,
be the material used be a blank LP or a plastic belt. The manufacture of
LPs was a long process of making a negative of the original cut, then
making a metal negative to press the actual LPs. The quality of the
final LP naturally depended on how many pressings had been done using
the same metal negative.
Good old days! Or were they?!!!
-- choro