PDP11/34a resurrection help

Ian King IanK at vulcan.com
Mon Jul 27 10:10:10 CDT 2009

You mentioned that you've removed cards, which prompts me to ask: did you replace them with grant continuity cards?  And did you verify that the NPG line is continuous, i.e. none of those cards you removed are making use of it?  The M7843 doesn't use NPG, but I don't know about your 'X' cards.  
From: cctalk-bounces at classiccmp.org [cctalk-bounces at classiccmp.org] On Behalf Of JP Hindin [jplist2008 at kiwigeek.com]
Sent: Sunday, July 26, 2009 1:37 PM
To: cctalk at classiccmp.org
Subject: PDP11/34a resurrection help

Greetings all;

I've had an 11/34a in the basement for some time now, but haven't ever had
it "working", nor have I messed with it in several years - which, of
course, means I've forgotten almost everything I ever knew about them,
which is almost nothing, so I'm starting from scratch, pretty much.

My 11/34a used to run a Xerox laser and came with a CDC9762, the card cage
looks like this:

1   M8266 -------------------------------------------|
2   M8265 -------------------------------------------|
3                             FLIPCHIP
4   M9301 YJ-----|   M7856---------------------------|
5   National Semiconductor Memory Board--------------|
6                    G7232---------|
7                    G7232---------|
8                    G7232---------|
9   M9202--------|   G7232---------|
10  M9202--------|                              X031-|
11  X020 --------------------------------------------|
12  X030 --------------------------------------------|
13  M7843 -------------------------------------------|
14                            FLIPCHIP
15                            FLIPCHIP
16                            FLIPCHIP
23  M9302--------|
(Where slots 1-9 are in the right-hand backplane when looking from the
front, and 10-23 are in the left-hand 14 slot backplane, which M9202
bridges between)

I've got the DL11-W set up in the same manner as the 300bps example in the
11/34 Users Manual (and the DL11-W Operators Manual), and at this time I
have the three X* cards as well as the M7843 card removed as I don't
believe they're required for boot.

I've verified on the backplane that +5 sits at a steady +5.06VDC and -15
is at -14.86VDC. I do not possess an o-scope, so the best I can do is with
my multimeter.

I have two problems. The first is that I do not own a "proper" cable that
goes from the DL11-W to a terminal. I own a VT240 and have crafted a cable
that goes from the Berg connector on the DL11-W through a header to a DB9,
which connects to a DB25/DB9 expander on the back of the VT240.
Obviously I've verified the VT240 is in 300/8O1 as required. To go from
the flat-ribbon to the DB9 I have what used to be the header from a CDROM
drive and have soldered the RX/TX/GND lines on the DB9 direct to the pins
on this header. Currently it looks like this:
B        5    GND
F        2    RX
J        3    TX
I -think- this is right, but I'm not positive. If I'm doing something
stupid, I'd sure love to have someone point it out.
Booting the 11/34a gives me nothing on console, but...

Even if my cable works the 11/34a doesn't seem to be acting like it is
supposed to. From my reading of the User Manual on power on, with the
front switches set to CONT and the BOOT/INIT switch toggled to INIT and
then let go, I should get the RUN light to blink out and then come back on
and stay on.
When I power on the unit the RUN light comes on momentarily, and then goes
out. When I toggle BOOT/INIT the light flicks on, and again, goes out. I'm
suspecting this means that somewhere the 11/34a is halting. If my console
worked, perhaps I would get something to it - although, for all I know the
console does work and the 11/34a is dying prior to it spitting something

I would love any and all input as to how I should proceed. I'm reading as
much as I can, but I've got a long way to go and help would be greatly

My thanks;
 - JP

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