PDP 11/34 rebuild

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sun May 25 16:13:00 2003

> The 11/34a I collected recently (BA11-L chasis, H777 PSU) and had
> difficulty getting to power up is in better shape now that it's had a
> good clean ; backplane inspected and all the dust & debris removed
> from its slots (via "fart in a can", ie compressed air :), the cards

Oh, you mean a can of pneumatic fluid :-)

> have had their edge connectors cleaned (india rubber) to be nice and
> shiny.
>
> Switching to DC ON, the fans whirr happily and the front panel now
> has "DC ON" and "RUN" LEDs on, with 000000 on the 7seg LEDs.
>
> If I try to halt (keypad CNTRL + HLT/SS), the RUN LED stays on and
> BUS ERR LED also comes on.

OK... This is rapidly becoming a FAQ here. You have an open-circuit grant
chain somewhere, and the M9302 terminator (I assume you've got an M9302
-- it's standard on the 11/34) is asserting SACK and locking the bus.

Start by pulleing the M9302 (if you only have the one backplane, the
machine will run without termination at the end of the bus, at least for
testing). If that gets the machine going, you need to check for missing
NPG jumpers and cards that are not correctly passing on the grant signals.

>
> I can enter an address via LAD, and DISADD shows it again, so the
> keyboard seems functional, but I can't change any memory with DEP or
> EXAM as the thing is "RUN"ning...
>
> No $ display on the console terminal yet either.
>
> Do I need to have the RX02 and RL01 drives connected & powered up for
> the CPU box to do anything? I shall try to get some grant cards to
> replace the RL11, RX211 and whatever the (non DEC) DR11 card is and
> see if I can at least get the console emulator to pop up on the
> terminal.
>
> Off to read the 11/34 Users Manual next (many thanks to Al Kossow for
> his site hosting this and so many other usefull docs)
>
> ta,
> greg
>
> Card configuration is :
> 1 AF M8266 KD11EA-control
> 2 AF M8265 KD11EA data path
> 3 AF M7840 KE11-B blackened/hot bits of PCB round resistor DIPs?
> 4 AB M9132 (soldered wires to FPanel)
> CF M7859 KY11-LB J1 to (FPanel)
> 5 AF M7891 128K*18 MOS mem
> 6 AF "Dr11 PHI733-1" card, unknown
> 7 AF M7762 RL11 controller
> 8 CF M7856 SLU/RTC option
> 9 AB M9032 terminator
> CF M8256 RX211 interface

I notice a couple of NPR devices there (the RL11, the RX211, maybe the
DR11) -- are those in the original slots? If not, you may have the NPG
jumper fitted on the slot where an NPR device is installed (which will
cause problems later) and missing on a different slot (which will cause
the problems you are seeing).

-tony
Received on Sun May 25 2003 - 16:13:00 BST