Date   : Sat, 07 Apr 2001 23:21:46 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: Q: BBC Model B + 3.5" FDD

UPSIDEDOWN POST! Corrected:
 
Philip Peake <philipp@...> wrote:
> Chris + Tina Saddler wrote:
> > I recently bought  a BBC Model B. It came with NO disk drive but it
> > does have the 8271 DFS upgrade and the DFS 0.9 ROM installed.
[snip]
> > When I try to format a disk with the command *FORMAT, the Beeb
> > responds after a short pause with the message "Disc fault 18 at
> > 00/00".
> The Intel 8271 disk controller can't drive a 3.5" drive (the timings are
> all wrong)
 
Yes it can. I've been using 3.5" disk drives with BBCs since about 1989. 
What's happening above is that there's no FORMAT command in the rom, so
when *FORMAT is issued, the DFS tries to find it on disk.  And, as the
disk isn't formatted, it gives an error message.
 
The problem with 3.5" disk drives on BBCs is not the 8271 FDC, but the
DFS.  DFS 0.90 and 1.20 do not wait long enough for the drive to become
ready.  This cannot be solved by changing the keyboard links as they set
track step and head settle times.  The patch I've written for DFS 1.20 to
create DFS 1.21 fixes this problem.  The patch is available from my and is
on my website at http://www.mdfs.net/Software/Rom
 
To solve the other problem, I can supply pre-formatted 3.5" DFS disks with
utility commands on them, including *FORMAT to format more disks.
 
-- 
J.G.Harston (JGH BBC PD Library) 70 Camm Street, Walkley, SHEFFIELD S6 3TR
jgh@...                - Running on BBCs & Masters with SJ MDFS FileServer
Z80+6502/CoPro+Tubes/Econet+SJ - - - - - - - http://www.mdfs.net/User/JGH/
                             Et In Arcadia Ego