The Last of The Line - test-drb@ccmp.vtda.org

17 May 2007

"Rod Smallwood" <RodSmallwood at mail.ediconsulting.co.uk> skrev:

...
  Well I think I understand the list. 
 But for clarity's sake here's the problem again.

 1. I have a number of PDP-11/94's
 2. The first three slots are Quad Qbus
 3. The missing KDJ11-EB would have been in slot one
 4. Slot two has a M9714 ALT PWR FOR KDJ11-E in it.
 5  Slot three is empty. 
 6. Slot four is a Unibus slot and has a M8191 KTJ11-B Unibus controller
 in it 
 7  Slot five has a M7547 TUK50-BB Tape controller in it.
 8. Slot's Six,seven and eight are empty
 9. Slot nine has a M9302 (UNIBUS TERMINATOR) at one end and a M9713
 (MIN. LOAD MODULE) at the other. 

 "Your mission Mr Phelps (Should you accept it) is to replace the missing
 KDJ11-EB with the lowest cost plug in alternative that will run"

 The winner gets (for the cost of the shipping) a 11/94 system unit box
 as described above. 
Sorry, but your options are very few.

The first three slots of that backplane are not Q-bus, but a special 
adaptation of it for the PMI memory and nothing else. You cannot use 
Q-bus memory on it, and no other Q-bus options either (atleast according 
to the manuals, I haven't tried in real life. I could check out if any 
signals differ, if it were real important).

Second, the Unibus adapter required some special signals from the 
CPU-board as well.

Your options are basically the 11/8x and 11/9x CPU boards. No others 
will originate the signals for the Unibus adapter required. Memory wise 
only PMI memory boards will do.

For an 11/94, all memory are on the CPU board, so for those, the two PMI 
slots should always be empty.
To make the power supply happy, you normally have some bus loads on them.

If you go for the 11/84 instead, you also need to find PMI memory boards.

That's the CPU/memory part of your system. You then need to configure 
the Unibus correctly, which means you need unibus grant cards in 
theright place of all empty slots. You probably also want some disk 
controller in that system.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol