Date   : Mon, 10 Sep 2001 13:59:57 +0100
From   : Tim Fardell <tim.fardell@...>
Subject: Re: XFER

Richard Gellman wrote:
> I've used DD PC disks on an A4000 before.. They quite capable of being
> formatted to 1.6Mb (acorn format) and worked reliably. Any disk can be
> formatted to any density, as long as the entire disk has a magnetic surface
> (as most do), as the drive sorts out where the data goes, and as long as the
> drive supports it. Except it seems on PCs, where the format program looks at
> the existing format, determines its 720K and decides thats the limit. PCs
> are odd.

You can format DD or HD 3.5" disks as DD or HD, provided the sensing
hole matches what format you want to use, or you have a Compaq drive
that ignores the sensing hole and just does what you tell it. E.g.,
sellotape over the hole in an HD disk will allow a PC to format it as
720k, and boring a hole in a DD disk will allow a (albeit unreliable)
1.44MB format. 

High-density 5.25" only seem to work in HD drives. I had an old
Commodore PET computer with 5.25" drives, and it could not handle HD
disks, and refused to format them. Same was true trying to use HD
discs in an Amstrad PC1512 with only DD drives - refused to format.
Even disks formatted as 360k in a HD drive could not be read by the
1512. I haven't actually tried in Beeb drives, but I strongly suspect
HD disks would be unusable, unless a HD drive is used in DD mode. 

3.5" HD disks are OK and have so far worked in everything I've tried
them in, including DD PC drives, an old HP drive and a data logger. 

Tim. 

-- 
This message represents the views of the author and does not 
necessarily accurately represent the views of BTexact Technologies.