Date   : Tue, 01 Jun 2004 10:39:27 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: Memory Tester / Watford DDFS not saving second sector

Timothy Baldwin <tim@...> wrote:
> I have a BBC Model B with Watford Electronics DDFS 1.54T and Watford 
> Electronics Shadow RAM. It is not saving the second sector of any file 
> created with OSFIND/OSBPUT.
> 
> The DDFS ROM is not corrupted (compared to copy on disc).
> 
> I suspect memory failure, can anyone recomend a memory tester program, or 
> suggest another course of investigation?
 
No, it's not a memory failure, it's a problem with the Watford DDFS.  This
is a classic problem with Watford's DFS. I encountered it when I worked
there. Somebody described it over the telephone and I followed the steps
exactly and was amazed to see the problem. Watford never did anything
about it.
 
The solution is to write your programs to work around the bug, or to use
Acorn's DFS.  The second option isn't much help if you need the double
density or double catalogue features. As I never managed to keep any of my
notes when I escaped from Watford I can't remember what the work-around
is, but if you email me a minimal program that displays the problems it
will remind me what the fix is.
 
-- 
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 - S:Re:[B]s - http://www.mdfs.net/User/JGH/