Date   : Thu, 25 May 2006 02:36:45 +0100
From   : "Ian Wolstenholme" <BBCMailingList@...>
Subject: Re: S18 problems?

Some versions of *ROMS in third party software (ie. not the official
command in 1770 DFS) can make the ROM listing on a BBC B duplicate
itself on screen because the ROMs present appear more than once
in the ROM table on an unexpanded machine.  In other words if
you do *FX142,x to select a language ROM there is more than one
value of x you can use to get, for instance, BASIC.

However *HELP should only report the ROM once if it only exists once
inside the machine.  If it's an EPROM then maybe a bit of sunlight
has crept in over the years and started to corrupt the contents?  If there
is something going slightly awry with the service code in the ROM which
deals with *HELP then I suppose it could be called multiple times.

Have you tried a different DFS ROM or even just checking that the
ROM is seated correctly in the socket with no bad contacts?

Best wishes,



Ian

----- Original Message -----
From: Kris Adcock
To:  bbc-micro@...
Sent:  Wed, 24 May 2006 22:45:40 +0100
Subject: [BBC-Micro] S18 problems?

Hey up,

Thanks to Wouter's rather smashing webpages listing what ROMs I can 
remove in order to help fault-find, I've managed to get this 
model-A-upgraded-to-a-B working ... almost. The only problem I have 
left (apart from a keyboard fault, but I'll take that to bits later) 
is that the Beeb gets confused about how many DFS ROMs are present! It 
can vary between 0 and about 4 - repeated combinations of ctrl+break, 
power-cycling and then *HELP can list the DFS 0.9 a random number of 
times.

The problem /seems/ to go away if I make S18 south instead of north, 
which according to the service manual limits the access speed of the 
sideways ROMs. I say "seems" because the fault is fairly random, and 
I've not spent hours trying to find a definitive way of making it 
happen. As the supplied DFS in this machine is actually on an EPROM 
I'm wondering whether it is an old, slow one. But then, why didn't the 
original owner complain about this? Is it a fault which would have 
gone away with a sideways ROM board (because I believe this computer 
used to have one in it before it reached me)?

Is limiting the ROM access speed going to negatively affect the 
stability of the computer? If not, I might be tempted to leave it. Or 
reflash a new EPROM with the 0.9 DFS.

Cheers,

Kris.
-- 
http://www.danceswithferrets.org/
"Fighting the ceaseless fight against literacy and good taste."
Te audire no possum. Musa sapientum fixa est in aure.