BBC troubleshooting (remote debugging)?

From: Andrew Davie <adavie_at_mad.scientist.com>
Date: Wed Feb 25 18:57:07 1998

>> Power on - BEEP
>That should be a two-tone beep. It's the standard BBC power-up sequence.


Ok... bEEP...BEEP!

>In mode 7, 1 byte of video memory corresponds to 1 character on the
>screen. So it looks like you have a problem with address line MA6 from
>the 6845. If you can borrow a logic probe, look at pin 10 of the 6845
>(look at 8, 9, 11 as well, in case I've miscounted) - there should be a
>square wave (pulsing) there, and then trace it through IC36c (again,
>there should be pulsing at pin 8 of this chip).


Will be a while before I can borrow a logic probe. However, removing and
reseating the 6845 has had no effect on the problem.

To be continued...

A
Received on Wed Feb 25 1998 - 18:57:07 GMT