1 Oct
2024
1 Oct
'24
5:26 p.m.
On Oct 1, 2024, at 11:30 AM, Chuck Guzis via cctalk
<cctalk(a)classiccmp.org> wrote:
On 10/1/24 07:54, Jon Elson via cctalk wrote:
For that matter, the first hard drive (IBM RAMAC) used hydraulic positioners, for both
cylinder and track select I believe. It had only one or two heads, so track switching was
a mechanical operation and actually a lot more expensive than changing cylinders.
The IBM 2314 was REALLY low tech. There was
almost no electronics in
the drives! They has a read amp, a write amp and a hydraulic "stepper
motor" with mechanical detents that moved the heads in response to step
in and step out pulses from the control unit.
IBM did know how to distill things down to the absolute minimum.
Remember, this was developed in the early 1960s and first shipped with
the first 360's in 1965.
Hydraulic positioning was used in several early drives. The Bryant
4000/CDC 6603, for example, had containers to catch leaks. ISTR that
the head assemblies weighed about 8 lbs each. The Univac FASTRAND drum, on the other hand, used
electromagnetic
positioning, employing a mechanical lever adder to come up with a binary
position.
-C
Interesting. It reminds me of technology used on PLATO terminals, both in the microfiche
projector option and in the audio disc player: a set of pneumatic pistons with stroke
length scaled 1:2:4:8 so you could get any of 16 positions by sending a 4 bit address to a
set of 4 valves. It's the only place I've ever seen where computer terminals had
connections to pneumatic supply lines.
paul