Date   : Wed, 24 May 2006 22:45:40 +0100
From   : Kris Adcock <kris@...>
Subject: 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.