Revive 11/34

Henk Gooijen henk.gooijen at
Fri Dec 8 15:17:22 CST 2017

Van: John Welch via cctech<mailto:cctech at>
Verzonden: vrijdag 8 december 2017 21:25
Aan: cctech at<mailto:cctech at>
Onderwerp: Revive 11/34

I am reviving an 11/34. Cards are:

Back/Fans [M8266--------]  Front of machine where keypad is.


           [M9312] [M7859]


           [OPEN]  [M7860]


           Bus grant in third from front slot

           [M9302] [M7856]
The 7856 is hooked to a cable/null modem (i think)/PC running

When I first powered on the programmers console said '7' and I powered
off, then back on, and now it says '5'

Any suggestions as to what to try first?  I may have the bus grant in
backwards.  I have other boards I can try.

John Welch

It is not completely clear (to me) how the modules are installed in the
backplane. Standing in front of the 11/34 processor box (looking at the
console), slot number 1 is at the right side. Each slot has 6 positions.
Position A is at the rear side, followed by B thru F. Position F is
thus at the front side.
There is no confusion about the first 4 slots.

Slot 1 and 2 hold the 11/34A processor boards, with M8266 in slot 1,
and M8265 in slot 2.
Slot 3, positions A and B has the M9312 bootstrap/terminator board,
and slot3, positions C thru F has the M7859 KY11-LB programmer's console
interface board.
Slot 4 holds the RL11 interface. This module does "DMA", so the NPR
jumper must be cut (open) on the backplane.
Slot 5 has an SPC in positions C thru F. I had to look it up; it is the

We are up to slot 6. Now things get "interesting" ... is that M7840 a typo?
The field guide says that this is a KE11-B Extended Arithmetic Element.
I do not know that board, is it "hex" or "quad"?
Not sure that board belongs there ... and if it is quad, I assume it has
to be in positions C thru F. I would suggest to pull this module, and
check the NPR wire presence on the backplane. You need a G727A or G7273
in this slot when the M7840 is removed.

If you are not skipping slots (see below), we are now at slot 7. There
is probably a G727A grant continuity card (aka "knockle buster") in
position D. That would be OK, but if the NPR jumper is cut on the
backplane, you would need a G7273 continuity and NPR card in positions
C - D. It is easy to have the G727 put in wrong. The 4 copper "jumper"
traces should be facing the next higher-numbered slot.

Then you say that the next slot has the M9202 (in position A - B) and
the M7856 (SLU and RTC) in positions C thru F.
The M9202 connects two system units (backplanes). So, what is the next
backplane?  Or do you have the M9202 in slot 8 and slot 9, positions
A - B?  I have never seen that ...

I am missing one slot. The 11/34 backplane has 9 slots.

When you power up the system, the display should show 6 octal numbers.
If only one digit shows a number (7 or 5 or whatever), there is an
issue with the console itself, or the M7859. The 6 digits of the display
are multiplexed. Maybe the connection cable between the console and the
M7859 - damaged/knicked? It is worth checking out the simpler things first.


More information about the cctalk mailing list