[vcf-midatlantic] Drive repairs, was Hard drive art

David Gesswein djg at pdp8online.com
Mon Apr 22 07:39:01 EDT 2019

On Sun, Apr 21, 2019 at 05:04:25PM -0400, Jason Perkins via vcf-midatlantic wrote:
> Some drives (Apple Widget, Plus Hardcard / Quantum) had a fine position
> sensor on the head arm. The Lisa disk uses this during a low level format.
Found picture of the drives online. Looks like they used an optical position
sensor similar to how my RK05's work. This was probably the last gasp of
that method before the track density got too high for it to work.

Are you saying the Widget only uses it to format? How does it determine
head position during normal operation? For my RK05 its always uses the
optical sensor for positioning the heads.

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