Date   : Fri, 04 Jun 2004 11:30:08 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: 3.5" disk drive

Mike Tomlinson <mike@...> wrote:
> >I've tried to attach high-density drives to my BBC, but I haven't been
> >successful since these drives work at 360rpms instead of 300rpms.
 
That's irrelavant. A standard 3.5" disks drive plus standard DD disks
works all the time.  I've been using 3.5" drives on my BBCs and Masters
since 1989 with no problems, other than minor timing errors in DFS 1.20
that are fixed in DFS 1.21.
 
> I could be wrong, but I think the extra high-density hole in the disk is
> used by the drive to determine whether it should spin at 300rpm or 360.
 
No it doesn't. The hole determines the data rate used, double-density at
250kbps or high density at 500kbps.  The disk always spins at the same
rate, 300rpm (incidently, the same a 8" drives). The BBC/Master can only
use double-density (and single, of course).
 
> Have you tried a standard 720k (DD) disk?
 
You must always use "DD", "blue", "720k", "single hole" disks with BBCs. 
The BBC and Master cannot use "HD", "black", "1.44m", "two hole" disks. 
The A5000 and later can use HD disks.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
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