Date   : Sat, 05 Jun 2004 10:20:11 +0100 (BST)
From   : Tim Fardell <tim.fardell@...>
Subject: Re: 3.5" disk drive

On Fri, 4 Jun 2004, Pete Turnbull wrote:

> Well, it's not 100%.  The long-term effect is poorer than if you use
> the correct media.  However, if it works at all (and it usually will,
> up to a point) it's OK for short-term storage.

Yes, maybe 100% was a bit optimistic! I think the oldest DD-formatted HD 
disk I have is about 3 years old, so not terribly conclusive on lifespan, 
but I've not encountered any problems so far. 

> It's also true that the difference between the magnetic coercivity of
> 3.5" double-density disks (650 Oersted) and 3.5" high-density disks
> (720 Oersted) is not very great, whereas the difference between 5.25"
> SD/DD disks (300 Oersted) and 5.25" HD disks (600 Oersted) is large, so
> you're more likely to get away with "misuse" of 3.5" disks than
> "misuse" of 5.25" disks.

Yes, unlike 3.5", I have never been able to get a HD 5.25" disk to work in 
a DD drive. It just won't have it at all. It is possible to format and use 
an HD disk as DD in an HD drive, but a real DD drive doesn't see it. 

Not that this is so important any more as 5.25" disks are virtually 
impossible to buy new now, although a handful of suppliers still stock 
them, but I guess they are probably old stock.