12 Nov
2008
12 Nov
'08
1:54 p.m.
On Tue, 11 Nov 2008, Sridhar Ayengar wrote:
Clearly you've never had a PCB trace lift off the board by having
soldered it too many times...
However, I did once have a very nasty fault on a PDP11/34. It would start
to boot RT11 (IIRC) and then trap to something like the power fail vector
a short way into the boot. The PSU was fine, ACLO and DCLO were not being
asserted, and so on.
After spending many hours going through the processor trap logic, I
finally found a DIP switch on the DL11-W console interface had been
knocked when I put the card into the machine. This changed its interrupt
vector into the one for the power fail trap. As soon as the OS enabled
interrupts on the conosle card, it got sent to the power fail trap
location.
-tony
I've always preferred dip switches over
jumpers.
Solder pads don't get knocked off, nor bumped into different positions