11/44: CSRs and Vectors

From: John Lawson <jpl15_at_netcom.com>
Date: Fri Dec 31 00:55:12 1999

  I am at the plateau of learning how to configure modules for
inclusion into a Unibus PDP11/44 system... and I'm having trouble
getting off the dime understanding the algoithms involved.

  I think I've a pretty good handle on how the grant chain works,
and of course I think I understand the concept of hardware
addressing and interrupt hierarchies and servicing. I just am
having trouble applying my limited knowledge to specific DEC hardware.

  Por ejemplo: I dredged the M8256/RX211 out of my 11/34, with the
object of hanging an RX02 on the 11/44. I have a DD11-CK (four slot)
backplane with one slot (4) available. I pulled the grant card, cut
the NPR jumper, and installed the M8256 in the slot. I checked
everything out electromechanically, all seems good: cables in the
right way up, RX02 on and running, all ok.

  On boot, the system came up normally until I typed $dir DY0: and
there was a mighty explosion, bits bytes and words rained down on me
and I blew the machine back into ODT. Thence, it refused to boot
again, returning me to the >>> every time, even after I powered it
down and back up again. [ >>> b db0 ]

  I then removed the M8256, restored the jumper and grant card, and
all is now well. (....Whhheeewwww...!!!!) I had visions of
irreparable damage and weeks of work and severe depression...

  So I assume that the various settings on the RX211 conflict with
the rest of the system. Having the documentation [PDP-11/44 System
User's Guide and the RX02 Floppy Disk System User's Guide] what
process must I accomplish to properly configure the Module so it
'plays well with others'?

  A Very Happy New Year to those whose Year is imanently New; and to
everyone else anyway, on the grounds that we all like good wishes.

  Cheers

John
Received on Fri Dec 31 1999 - 00:55:12 GMT