On 07/01/2009 01:27, Bob Armstrong wrote:
I have a BA11-N chassis that says
"11/03-L" on the front, and the
backplane in it is an H9273-A. I want to get this to work with a 11/03 CPU
(a real KD11-F M7264) but there's something strange about this backplane
that I can't figure out.
The boards I'm using are the M7264, an M8044 (MSV11-D), M8017 (DLV11-E)
and a BDV11. In a small, 4 slot 11/03 chassis (a BA11-S, I think)
No, that'll be a BA11-M, with a H9270 18-bit 4 x 4 serpentine backplane.
BA11-S is a box with a H9276 9-slot 22-bit backplane, used for a
PDP-11/23plus.
all these
boards work fine together, however in the BA-11N there's no joy. It powers
up, but the processor appears to halt immediately - it never executes the
BDV11 bootstrap.
But, if I replace the 11/03 CPU in the BA11-N with a 11/23 CPU card, then
everything is fine. So the 11/03 works fine in the BA11-S but not in the
BA11-N, and the 11/23 works fine in the BA11-N.
It seems fairly likely that there's some kind 16/18/22 bit addressing
issue here, but what's the fix? It must have been possible to use the
KD11-F in the BA11-N, given the 11/03-L designation.
Not necessarily, the BA11-N was designed when the dual-height LSI-11/2
(M7270, KD11-H) was used, and then was also used for the 11/23 systems.
The issue is not the number of address bits, which won't matter at all.
It's that your H9273 backplane is set up for an 11/23 and won't have
W2 and W3 inserted, but they need to be for a quad-height M7264 (and
only for that board AFAIR, don't insert them if you use a quad-height
KDF11-B).
FWIW, the backplane has not been field upgraded with
wire wrap to add the
extra address bits. In fact, the H9273-A doesn't even have wire wrap pins
at all - the pins are all cut off right at PCB level. Is this the standard
backplane for a 11/03-L system? I'm wondering if at some time maybe the
whole backplane was replaced with a newer one.
No, that's normal for almost all Q-bus backplanes, and you do have the
normal backplane for a BA11-N.
--
Pete Peter Turnbull
Network Manager
University of York