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[Vintage Computer Festival]

On Sun, 25 Sep 2005, Tony Duell wrote:

> > Apple Disk ][ drives used a similar mechanism.
>
> Not really.. The Apple ][ head positioner (which, IIRC, was actually a
> Shugart design, certainly I've seen it in a non-Apple drive, I think it
> was a Shugart) had its own stepper motor. You could move the head between
> tracks under program control.
>
> The Smith Corona drive had one motor. It drove the spindle, and moved the
> head. After each revolution of the disk, the head moved to the next track
> inwards, when it got to the innermost track, it moved (automatically)
> back to the outermost one and the sequence started again. The disk was
> essentially a sequential-access thing, like a tape.

The distinction is correct.  I should've noted that the head positioning
disk with the spiral groove in the Disk ][ mechanism is not driven by the
main motor and a clutch, but by its own stepper as you've pointed out.

-- 

Sellam Ismail                                        Vintage Computer Festival
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