What would cause a regular pattern of bad sectors?

[dwight]

Heat damage can cause a fold or wrinkle as well.

Many format programs don't look at the index anymore as it isn't important for reading the disk. It is only used to indicate that the disk is turning.

That is why you see it moving each time you reformat. It is the same place on the disk surface.

Dwight


________________________________
From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Paul Koning via cctalk <cctalk at classiccmp.org>
Sent: Monday, April 24, 2017 6:16:26 AM
To: Terry Stewart; General Discussion: On-Topic and Off-Topic Posts
Subject: Re: What would cause a regular pattern of bad sectors?


> On Apr 24, 2017, at 8:44 AM, Terry Stewart via cctalk <cctalk at classiccmp.org> wrote:
>
> Hi guys,
>
> Ive been extracting data off a 3.5 inch windows XP-formatted floppy disk
> with many bad sectors.  The odd thing is it's always the same bad sectors
> on every track.  Such a 3, 8, 12 and 17.  Once or twice it might be just 3,
> 8 and 17.  Or occasionally 3, 8, 9 12, 17.  This patten is the same for
> every track.  It's  (more or less) always the same sectors that are bad.
> Why?  I can't believe natural degredation would be so consistent.  Anyone
> have any thoughts?

A radial scratch on the media?

        paul