27 May
2005
27 May
'05
8:08 a.m.
On 27 May, 2005, at 10:29, Eric Smith wrote:
Tom wrote:
The least obvious part of it was how to make a system where the head
did not scrape away the coating.
Poulsen had shown how to record to a fast-moving wire. His telegraphone
had severe head wear. Agfa had shown how to use a paper tape coated
with iron oxide to be able to work at lower head to tape speeds and get
less head wear, and the tape backing was subsequently improved to
acetate film.
How to make this work when the magnetic coating was on a rigid surface
was far from obvious. Magnetic drum assemblies were extremely tricky to
adjust. There was a reason why they used fixed heads - the principle of
moving along the drum axis had been known since Edison made the
phonograph. The rason why drum storage used fixed heads was that nobody
had figured out how to make flying heads yet, so they needed a very
rigid assembly where you could use screws to make micrometer
adjustments.
--
-bv
certainly, IBM did not invent the disk drive.
They may have
commercialized it first, but I doubt that even.
I'd be very interested to hear of any working magnetic disk drive,
commerical or otherwise, predating the IBM RAMAC.
Hand-wave -- it was obvious.
In hindsight it looks obvious. I'm not convinced that it was
obvious 50 years ago.