FW: RK05 question

From: Paul Koning <pkoning_at_equallogic.com>
Date: Tue Jul 13 08:07:22 2004

>>>>> "David" == David V Corbin <dvcorbin_at_optonline.net> writes:

 David> More seriously. I wonder how good the rotational stability is
 David> on the drive. Mny of the reasons for using "hard sectored"
 David> media was because a) Drives "wobbled", and b) Accurate timing
 David> electronics were "difficult".

I think the motor is the kind whose rotation speed is tied to the
power line frequency, so assuming normal stable utility power the
rotational stability will be excellent. Also, the motor power is
fairly low compared to the inertia of the disk, so any short term
variations in motor power have only a small effect on RPMs.

 David> If the drive motor speed is stable (over the course of a
 David> rotation), it*MIGHT* be possible to alter a drive to just use
 David> the "home" slit and synthesize the individual sectors. Never
 David> tried this with an RK05 [heck havent touched one of them in
 David> over 25 years!], but I have used this technique to synchronize
 David> otgher items.....

I suppose that's possible. One way to do it would be to build a PLL
that's locked to the start of track pulse, and derive a 12x or 16x
sector clock from that. Or, analogously, you could use a PLL to
derive a 16 sector clock from the 12 sector clock (multiple by 4/3rd,
not hard with a PLL). That's probably a good solution...

    paul
Received on Tue Jul 13 2004 - 08:07:22 BST