On Friday, 3 July 2015 20:47:41 UTC+1, Mike Tomlinson wrote:
En el artículo ,
whisky-dave escribió:

What if you have a RAM problem, I remmeber they were more diffcult to pinpoint
which chip was faulty

You can disable alternative 16K halves of the RAM with a jumper which
made it easier to locate the bank in which the faulty chip sits. Also,
the 'back of a finger' technique is useful to find a chip running hooter
than the others - that is usually the suspect one.

RAM faults on the BBC B were pretty rare -

Not that rare I repaired quite a few, one of our studetns wrote a program to dump a dot on the screen for every memeory location that was working where there was a gap you could work out what chip was at fault. CS1 & CS2 come to mind. I even have a couple of service manuals somewhere as I went on the acorn servicing corse.

the most common faults IME
were the 6522 VIA chips, often the one that provided the printer and
user ports, as the I/O lines from the user port were presented
unbuffered to the outside world and were prone to damage from people
plugging stuff in with the machine powered on.

ours was the power supply and the RS423 chips.