Subject: Re: VAXstation 2000 Progress --- MFM controllers?
To: Allison J Parent <firstname.lastname@example.org>
From: Michael Kukat <email@example.com>
Date: 02/18/2000 07:39:56
On Thu, 17 Feb 2000, Allison J Parent wrote:
> <1) I think you have to assume there are 1/2 as many sectors per track.
> no. That would be dependant on the controller and the sector size. Often
> for a fixed sector size the RLL encoded one will have more sectors.
I think we are talking of the classic way to format disks. Today, the inner
tracks have less sectors than the outer tracks, i don't think, this is easy
for the HDC9224. The way i know it from earlier times: MFM uses 17 sectors
and RLL uses 26 sectors. This was fixed, so you can calculate the gain.
> <2) You have to re-low-level format the drive.
> It's a must going either way. Also only format the drive when it's reached
> operating temperature. It does make a difference.
And in the final installation position, the drive should be formatted in
exactly the same situation as it sees the rest of its life in action :-)
> <3) Not all drives will tolerate the change.
> Some are not up to doing reliable RLL. Interrelated with controller.
> Also those that don't do rll well often have a poor MFM record or are
> very old drives.
I never had problems, but the times i did such things are about 10 years away,
there i only has 20-40 MB disks to try with. Maybe they just are uncritical.
Michael@camaronet.de, Rottweil/Germany, http://www.camaronet.de
Visit the german VAXpage: http://www.vaxpower.de