Date   : Sun, 06 Jun 2004 13:22:57 +0100 (BST)
From   : Pete Turnbull <pete@...>
Subject: Re: 3.5" disk drive

On Jun 6, 10:53, Jonathan Graham Harston wrote:
> > Message-ID: <1086349807.18038.36.camel@...>

> Old 40 track 5.25" drives used heads that are half the width of 80
track
> 5.25" drives.

That's a typo, Jonathan obviously meant that 80-track heads will write
(or read) tracks half the width written (or read) by 40-track heads.

> The problems occur if you format a disk with a wide head, and then
write
> data onto the disk with a narrow head.  You can get bleed-through of
data
> from the area outside the narrow data track from the old wider data
track
> laid down by the wider head.

You don't really get bleed-through.  What goes wrong is that if you
subsequently try to read that disk on a drive with a wide head, it
picks up the original signal as well as the new one.

> The best thing to do is ensure that you format disks with a
narrow-head
> drive, either a newer 40-track drive or an 80-track drive in 40-track
> mode.

Assuming it was a completely blank, unformatted disk, or has been
degaussed :-)


-- 
Pete						Peter Turnbull
						Network Manager
						University of York