Strange RLV12/RL02 problems
Steve Maddison
I'm tinkering with an 11/73 fitted with an RLV12 and two RL02 drives, of
which one is currently functional. I've verified that everything is
connected up and terminated correctly and the most things seem to be
working fine. I can boot from RL02 and the drive passes diagnostics
without error. Under specific (and completely reproducable)
circumstances however, the whole (sub)system seems to hang.
One such case is when trying to access the RL02 via VTServer. Again,
I've verified that connections are good and have even managed to copy
from virtual tape to another virtual tape record, so I know the PDP-11
is running the copy program OK. Selecting the RL02 as output device with
rl(0,0,0) just does not want to work. No error is reported and the
system simply hangs. This is with a known-good disk pack.
Trying to diagnose the first problem, I came across another example,
namely trying to run the XXDP diskless controller diagnostic, VRLB and
the first of the "real" tests, ZRLG. I left the former running for half
an hour last night, which I'm assuming is enough for a relatively simple
controller test, but it still hadn't completed. Halting the box produces
a short flurry of garbage on the console, then the numbers 474, which I
suppose is the end of a memory address. This was all with the auto-drop
limit set to 1 which, if my interpretation is right, will have the test
stop if any errors should be detected. Of course, this could be
completely down to optimistic expectations on my part - how long is this
test meant to take?
I'm not sure if the two problems are related, but the symptoms are
similar enough for me to suspect a common cause. The only thing I though
of was that maybe I've got the vector address wrong. I believe it's
jumpered to the standard 160 but I'm not sure how to verify this. Does
being able to boot and run RT-11 and XXDP from the RL02 say anything as
to whether this is set up right?
For completeness' sake, here's a quick sketch of which modules are
installed and where (it's a H9276-A Q/CD backplane). Slots 6+ are empty.
I've also tried removing the DEQNA and shifting the RLV12 up a slot, but
it doesn't seem to make any difference.
A B C D
1|< M8192 KDJ11-AA >| |
2|< M7195 MXV11-BF >| |
3|< National Semiconductor Memory Module (4MB) >|
4|< M7504 DEQNA-M >| |
5|< M8061 RLV12 >|
If anyone has any answers or even ideas regarding what to try next, it'd
be great to hear from you.
Regards,
--
Steve Maddison
http://www.cosam.org/
"Hardware: (n.) The parts of a computer you can kick."