[Gllug] re: winchester discs

[t.clarke]

Back in the 80's when we were using a TI990 computer system, we migrated
from the 'washing machine' style removable discs  (Calcomp if I recollect
correctly) to a Fujitsu 'winchester' disc.   Apart from the fact that the
Fuji disc was semi-sealed (it had a 'breather' hole somewhere with a filter),
the key difference was in the head-technology:

the old style discs used a form of 'ski ramp' to load the heads;
the disc platters were spun up and when they reached the correct speed
a heavy-duty (and I mean heavy duty, like it could quite happily chop your
fingers off !) linear-motor/giant solenoid thingy pushed out the heads down
a sort of ramp which lowered them on to the disc surface. Of course, they
never (intentionally) touched the disc surface but flew above it (the heads
being crafted with little aerofoils from memory.

the winchester technology differed radically in that
a) the heads flew closer and 'landed' on a specially lubricated zone when
the discs were powered down
b) the heads were moved by a radial actuator instead of the straight in-out
method of the older discs

The original winchester discs whilst being more compact than their older
ancestors were still huge by todays standards. But I believe the underlying
technology is still much the same; just shrunk somewhat.


Tim

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