Date   : Sun, 17 Oct 2010 13:44:33 +0100
From   : jgh@... (J.G.Harston)
Subject: Fw: DD & HD Floppies

Dave Curran wrote:
> Silly question, but I'm just taking a step back from this and thinking that
> instead of adapting HD disks to work in DD drives, what are the chances of
> getting standard 1.44M HD drives to work on the BBC?

Standard 1.44 HD drives *DO* work with BBCs, it's the *DISK* that's
different, that's why there's a hole/nohole on the disk. The hole
tells the drive what write current to use, and the computer sends
data at either 250KHz or 500KHz.

> The ideal would be adapting one of the DFS's to work with 1.44M disks -

See all the work Beardo has done with HD disk access. It is *very*
difficult on a BBC due to the incredibly tight access loops to
get the data transfered fast enough, and needs customised hardware
and rewritten firmware. See
   http://beebwiki.jonripley.com/High_density_floppy_disc_access
   http://regregex.bbcmicro.net/#prog.edospat
and the thread starting here back in 2005:
   http://mdfs.net/Archive/BBCMicro/2005/10/30/210658.htm

-- 
J.G.Harston - jgh@...