Date   : Tue, 20 Sep 2005 20:45:55 +0100
From   : "Adam D. Barratt" <lists+bbc-micro@...>
Subject: Re: Poorly Master?

On Tue, 2005-09-20 at 18:12 +0100, Richard Gellman wrote:
> Adam D. Barratt wrote:
[...]
> >Once I use the correct format, it works fine. On the assumption that my
> >CMOS battery is faulty/flat/dead, any suggestions as to where to get a
> >new one? (bearing in my mind that I'm quite happy plugging, unplugging,
> >attacking stuff with tools, but generally not competent with a soldering
> >iron :-)
> >  
> >
> You can make a battery pack quite easily... the one in mine is 3 x AA 
> batteries, in series with a resistor and a diode.. I can't remember the 
[...]

Well, after resetting the clock correctly, it's still going a couple of
hours later (it was turned off for around an hour in the middle).

I did reseat the battery connector when I took the cover off shortly
after powering it on for the first time and being unable to get a video
signal (not the Beeb's fault - it appears my tv only likes it on av2,
not av3) as it wasn't properly pushed on. Is it possible that the
battery wasn't flat but merely not connected? How long should it take
before it forgets the time again if the battery is dead?

> >That was one of my first thoughts, as the symptoms are similar to those
> >you'd get from other systems (e.g. plugging floppy or IDE cables in
> >upside down in PCs).
> >
> >However, at least the BBC end of the cable appears to be fine - it's
> >keyed, and the red stripe is aligned to pin one. It's possible that
> >something's wrong at the drive end, but I'm not really sure what I'm
> >looking for there.
[...]
> Now if your drive has been designed by intelligent people (move along, 
> nothing to see here...) there'll be a slot in the circuit board to key 
> the edge connector - most edge connectors don't have the opposing key, 
> so its easy to flip it upside down. From memory, the red wire should be 
> at the wide end of the edge (the short end has two contacts).

Thanks for the hint. The edge connector is indeed keyed, although the
cable isn't. It appears that pin one - and therefore the red stripe - is
actually the short end; having turned the cable round, I can now
catalogue a random selection of the old disks I had around.

>From memory, I'm guessing it's a 40 track drive. Once I'd found the
correct stepping (2 or 3 appears to work) it will quite happily run
software from 40 track discs, but all of the half dozen 80 track discs I
tried die with

  Disk error 18 at :0 XX/01

for varying values of XX, which my memory says means the disc and drive
track settings don't agree. The drive doesn't appear to be switchable,
so I guess it's back on ebay for a new disc drive.

(One of the discs that does work has now left with an interesting
mystery to ponder - namely why one of my old bits of code with "ON ERROR
CALL !-4" at the top causes the machine to reset at seemingly random
points. I know what the code does - and therefore /why/ the machine is
resetting - but not where the problem is - particularly as if the line
is removed the software operates without error. Ah well, one for a rainy
day ;-)

Thanks for all the help and suggestions everyone provided.

Cheers,

Adam