PDP11/83 qbus layout.

[Robin Birch]

In message <Pine.NEB.4.05.9812232234500.23424-100000 at spektr.ludvika.se>,
Jorgen Pehrson <jp at spektr.ludvika.se> writes
>
>(Sorry for the rather lenghty post)
>
Don't worry about that.
>Hi,
>I'd just try to boot my newly aquired PDP11/83 and was planning to install
>2.11BSD. But I've run into one (small?) problem. If I just try to boot
>from DU0: it says: 
>
>Trying DU0
>
>Error 20 
>Controller Error
>
>And if I boot the install tape from the TK70 drive and run disklabel,
>all accesses to the RD53 drive just times out. So I was going to remove
>all unwanted QBus boards from the boxes. And that's what I was going to
>ask...
>
A good plan
>
>Is there something special I have to think about, like there's some slots
>that can't be used, some boards must be in a specific slot and so on?
>
There are rules about where boards can go which is an off shoot of the
BG lines and so on.
>This is the current layout (which is exactly as it was when it was taken
>offline, or so I think)
>
>11/83 (173QA-B3, I think this is a normal BA23 enclosure):
>(As seen from the back) Also contains one TK70 drive.
>    
> ____________________________________________
>|Dataram 40903 revG     |        Empty slot  | (2mb ram)
>---------------------------------------------
>|                    M8637-EH                | (2mb ram)
>---------------------------------------------
>|                    M8190-AE                | (83 CPU)
>---------------------------------------------
>|     M7559             |         M7504      | (TK70, DEQNA)
>---------------------------------------------
>|     M8020             |        Empty slot  | (console?)
>---------------------------------------------
>|                    M7957                   | (DZV11)
>---------------------------------------------
>|                    m3104                   | (DHV11)
>---------------------------------------------
>|     M9404            |          Empty slot | (1st Qbus conn)
>---------------------------------------------
>
>Expansion box (173QA-B3)
>(From the back) Also contains one RD53 and one dual floppy.
>
>_____________________________________________
>|M9405-YA               |        Empty slot  | (2nd qbus conn)
>---------------------------------------------
>|                     m3104                  | (DHV11)
>---------------------------------------------
>|     m9047             |        m9047       | (grant cont x2)
>---------------------------------------------
>|     m7555             |        Empty slot  | (RQDX3)
>---------------------------------------------
>|     m7512             |        Empty slot  | (RQDX1E)
>---------------------------------------------
>
>Plus one external disk box with two RD53 drive. (This system only uses one
>drive though.)
>
>Now, what I obviously want to keep is:
>the two RAM boards, the CPU, the console board, tk70 controller, deqna,
>rqdx3.
>
What you are calling the console board probably isn't, or if it is then
you want to use the one from the CPU card rather than the M8020 (DPV11 I
think?).

>What I want to loose:
>the rest of the serial boards, the rqdx1e board and the floppy drive.
>

What I suggest is this.  Keep the CPU and the mem, the TK controller and
tape, the deqna, the RQDX3 and a serial card (You never know when a
spare serial port is going to be useful - printers, simple comms to a
PC, spare terminal etc etc etc).

A possible layout would be:

|Dataram 40903 revG     |        Empty slot  | (2mb ram)
---------------------------------------------
|                    M8637-EH                | (2mb ram)
---------------------------------------------
|                    M8190-AE                | (83 CPU)
---------------------------------------------
|     M7559             |         M7504      | (TK70, DEQNA)
---------------------------------------------
|                    M7957/M3104             | (DZV11) or (DHV11)
---------------------------------------------
|    M7555              |        Empty slot  |
----------------------------------------------
|     Empty slot        |       Empty slot   | 
---------------------------------------------
|     Empty slot        |         Empty slot | 
---------------------------------------------

>What do I have to do to make this work? I would preferrably want to fit
>all those boards in the main CPU enclosure box. Do I have to re-assign any
>addresses (or vectors, or what the correct PDP-speak is). Are there any
>slots in the enclosure that are a no-no for the dual-sized boards?
>
You would have to check with others which of the serial boards is best 
supported under 2.11BSD.  Steve Schultz is your best point of contact
for this.

Looking at you aoriginal configuration I think that the empty slot by
your M8020 is your problem (unless there is a bus grant card in there)
as there wouldn't be any BG continuity.

This should work and allow you to ditch all of the rest. (saving it for
a rainy day of course :-)).

Regards

Robin
____________________________________________________________________
Robin Birch     robin at falstaf.demon.co.uk

M1ASU/2E0ARJ    Old computers and radios always welcome