From:	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: direct hard drive controll?
Date:	10 Jul 2000 16:28:02 GMT
Organization:	Aachen University of Technology (RWTH)
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Damian Yerrick <Bullcr_pd_yerrick AT hotmail DOT comremovebullcr_p> wrote:
> On Fri, 07 Jul 2000 21:03:30 GMT, nunnayod AT mbiz DOT nez (CaffineLady)
> wrote:

>> I don't want to read any data (infact the platter will probably be removed),
>>and I need the operation to be fast because I need to switch between tracks
>>really really fast (to move the mirror Im gonna glue to it back and forth). 

> Most modern hard drives use a voice coil to move the head.  If you
> just want to move a mirror real fast, why not program the voice coils
> yourself with a sound card?

I second this suggestion. If the hard drive is even remotely modern,
it won't move the heads at all without the platters in, anyway. Modern
drives don't use stepper motors any more to position their heads. Do
successfully find discrete tracks with their continuous actuator, they
need special information on the platters ('servo information'). This
implies that without the platters, the head doesn't know where it is,
and no command from the controller will reproducibly position it
anywhere but at the emergency stoppers :-(
-- 
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.

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