Date   : Tue, 23 Mar 2010 11:03:49 -0000
From   : dominic@... (Dominic Beesley)
Subject: Re-using floppies

I dug out all my school discs a few months ago to try out.

All the 5.25 HD formatted as DD had problems - most completely unreadable.

All but 1 (out of about 5) of the 3.5" HD formatted as DD worked fine the
duff one had a big scratch on it. However, may be down to a case of
"selection". I remember HDs being less reliable at school probably not
helped by being carried around with speakers in my school bag - long story.
So the ones I've still got are the ones that worked. I suspect discs from
different manufacturers had different success rates - I recall the black
discs borrowed from my Sunday job office were less likely to work than the
blue ones (all HD). Unfortunately they all got eaten by the dry-rot
infestation in my workshop.

Now I can afford a few quid I bought 50 DS DD for about ?30 can't remember
where from but there's loads on ebay. So far I've only actually used - now
I've got hard discs and Datacentres to save to!

Dom

> -----Original Message-----
> From: bbc-micro-bounces+dominic=brahms.demon.co.uk@...
> [mailto:bbc-micro-
> bounces+dominic=brahms.demon.co.uk@...] On Behalf Of
> Anders Carlsson
> Sent: 23 March 2010 08:19
> To: bbc-micro@...
> Subject: Re: [BBC-Micro] Re-using floppies
> 
> Rick Murray wrote:
> > the HD head is narrower than the DD
> 
> Pete Turnbull wrote:
> > No, they are exactly the same width.
> 
> I believe you both are correct, depending on the context. A 5.25"
> floppy
> disk is either 40 or 80 tracks (give or take those 35 and 77 track
> formats)
> and in this case there may occur inconsistencies if writing a 40 track
> floppy disk on a 80 track (1.2 MB) drive. However a 3.5" floppy disk is
> always (?) 80 tracks, only varying density and magnetic strength so in
> this
> case the head on a 1.44 MB (HD) drive should not be more narrow than
> the one
> on a 720K (DD) one. The difference in coercivity between 3.5" DD and HD
> is
> smaller than it is for 5.25" DD/HD, which means you might get away with
> formatting and using 3.5" disks of the wrong type but usually fail
> terribly
> if you try to use a 5.25" HD floppy disk on a DD system.
>