Date   : Tue, 20 Sep 2005 18:12:22 +0100
From   : Richard Gellman <splodge@...>
Subject: Re: Poorly Master?

Adam D. Barratt wrote:

>>>  > *TIME
>>>      ,00 Xx 1922.23:12:06
>>>  >TIME$="Mon,08 May 1900 12:00:00"
>>>      
>>>
>>You missed the dot out ----^
>>    
>>
>
>Gah, so I did. I'd forgotten how picky^Wprecise the Beeb can be about
>these things.
>
>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 
resistor's value though :( For this, you'll need to salvage the 
connector to the battery unit you have already. The board connector is 
rotatable, so in the event of bypassing the keying and plugging it in 
the wrong way around, it'll still work :)

Note: If you've got one of the really really really old battery units, 
you'll find a rather dodgy lithium battery sitting next to the speaker 
(some variants may have this moved elsewhere, but it'll be a single 
unit, looking rather boring). This lithium battery (if you have one) 
needs to be disposed of properly, and ideally standard duracells used to 
replace it. If you're concerned about whether the system tries to charge 
the batteries, it doesn't. There *is* provision on the board for this, 
but its not enabled on the board as shipped.

>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.
>  
>
Firsrtly, don't go thinking a PC floppy cable will work - it won't - at 
least not properly. PC floppy cables come with a twist - literally - 
that swaps the drive IDs. For some reason, in the BBC's case it breaks 
something else too (in my experience; even switching the drive ID 
internally didn't make it work with a PC floppy cable). BBC floppy 
cables are straight, IDC one end (the BBC end) edge connector on the other.

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).

-- Richard