Date   : Thu, 19 Mar 1998 19:58:59 +0000
From   : Stuart William McConnachie <stuart@...>
Subject: Re: Wierd Hardware Problem!

In message <21484.199803191806@...>, Chris Walton
<cdw@...> writes
>I recently obtained an old BBC B, but although the machine switches on OK 
>(it displays the 'BBC Computer 32K' bit), it won't respond to any keyboard 
>presses EXCEPT those involving <BREAK> (i.e. <shift-BREAK>, 
><ctrl-BREAK>, etc).    The keyboard and keyboard cable check out fine on 
>another BBC.   The only clue is that the machine gives only one 'beep' 
>when you switch on, and doesn't 'beep' when you press <ctrl-BREAK>.    
>Anyone know what might be wrong, before I use the machine for spares?
Sound like a problem with the System 6522, but I've not seen this happen
before.  The 6522 was used to attach the Keyboard and Sound hardware to
the 6502 system address bus. You can still get 6522 timers from Maplins
part no UF25C.  Can't remember which one the system one was, there were
2 in the Beeb one above and one below the 6502 processor.  Maybe someone
else can help you there.
BREAK works because this is connected directly to the system reset line.
I assume the single beep you get when you power up is a function of the
sound chip powering up?

Stuart.
-- 
Stuart McConnachie (stuart@...              )
43 The Hollows, Long Eaton, Nottingham, NG10 2ES, UK
Mobile: 0966 224307