Date   : Tue, 28 Mar 2006 21:01:20 +0100
From   : Fragula <fragula@...>
Subject: Model B NMI PITA.

Ahh.. I'm getting to the root of my various problems it seems. Well, the
Beeb related ones anyway.

Said various problems amount to this.

My model B got 8271 FDC upgraded, many moons ago, that was then upped to
a STL DFDC, which is a lovely little bit of kit (and probably irrelevant
to this really...) Then later, I stuffed all the appropriate Econet
components in, did whatever it was I had to do with S2, powered it up,
and watched my fledeling Econet burst spectacularly into inactivity.

A learned member from Cambridge visited, and after some (quite a lot
IIRC) of faffing around, it worked.. (BTW NFS3.34 works just great on
the boards where the econet works!) Some while later, I put the DFDC
back in, fiddled until that worked, and, it seems, the econet didn't.

Its not been too much of a problem, as I'd picked up another two
econet-only model Bs, and also had an econetted Master 128, which did
fine for transferring files from disk to net. However, master keyboards
being what they are, that, and its 3 compadres, have fallen from favour.
I need to get a B up with Econet and FDC.

So I tried to transfer the DFDC from one model B to another, cut S9 as i
need the NMI. quick test, and voila, another non-functional econet! :'(
Shorting S9 out with a screwdriver seems to "sort" the problem, but that
wont do the FDC'd model any good.

The Good Old Model B seems to need Link S9 closed to work with Econet,
but open for the disk controller.

Anyone got any easy clue for me? I can't read the circuit diagram until
Thursday, when my new glasses arrive.

"Its not possible" is not the correct answer, I'm sure, but it doesn't
look easy at the mo.

Cheers!

M.