DEC PDP-11/73 in BA123 cabinet

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I’m in the process of building up a PDP-11/73 system in a BA123 cabinet.

Eventually this system will be able to boot either RT-11 V5.7 or RSX-11M+.

It will have a SCSI2SD device and CMD CQD-220 controller as the primary hard drive(s).

I have a few things to learn along the way. I’ll need to learn how to SYSGEN both RT-11 and RSX, as I plan to have at least two MSCP controllers in the machine (one for the CQD-220, and the other being an RQDX3).

Backplane Configuration

The table below shows how the backplane is currently populated.

M8190-AB (KDJ11-BB)
Camintonn non-PMI RAM board
Camintonn CMLV11-J (4-port SLU) Empty
M8029 (RXV21) Empty
M8061 (RLV12)
M3104 (DHV11-A)
M3104 (DHV11-A)
CMD CQD-220 (SCSI) M7516 (DELQA)
M9047 (Grant Continuity) M7555 (RQDX3)

There is an excellent table comparing the various DCJ11-based processor board here.

SCSI2SD configuration

I plan to use a SCSI2SD board as the primary hard drive for the BA123. This will make it easy to transfer PDP-11 hard drives between the BA123 cabinet and SIMH (all I will need to do is copy the relevant SIMH virtual file to/from the relevant sector range on the MicroSD card, using the Linux “dd” command).

Details of the SCSI2SD setup are here ->

Doing a SYSGEN in RT-11 V5.7

I found this helpful dialog showing the typical SYSGEN Q&A process:

The RT–11 System Generation Guide (for RT-11 Version 5.6) Order Number AA-M240E-TC is also very helpful reading.

The main changes that I want to address during SYSGEN are:

  • Provide for 4 x DLV11-J ports (of these one will be the system console, one will be for a TU58 emulator, and a third port will be for a serial printer)
  • Provide for 3 x MSCP controllers
  • Provide for at least one 8-channel multiplexer

Moving the SYSGEN’d RT-11 V5.7 to the BA123 cabinet

When I moved the dual-MSCP setup to the BA123, I had a problem booting up RT-11 V5.7. Each time (and no matter whether I was booting from the SCSI2SD drive DU0 on the first MSCP controller, or from the RX33 on the second MSCP controller), the boot process would start but then give the following error: “mon-f-trap to 4 012703”. This was cuased by me not having a DLV11-J in the BA123 cabinet (I had selected a DLV11-J during the SYSGEN process). Once I installed the DLV11-J (with Console on Channel 4 disabled), the SYSGEN’d RT-11 V5.7 would now boot successfully from either the SCSI2SD board or from the RX33 floppy drive.

DLV11-J Bulkhead

To Physically connect the DLV11-J to the outside world I used a bulkhead that DEC calls a “DLV11-J Filter Panel”. This bulkhead has 4 x DB25M connectors on it, which can be used to connect up all 4 ports on a DLV11-J. The DEC Part Number is 5415221 (the “21” is however hidden beneath the 40-pin Berg header), and the PCB is marked “5015220”. The schematic for this panel are available here -> CKDLVJ1 Field Maintenance Print Set, DEC Part Number MP00990-01. Page 13 of the MP00990 Field Maintenance Print Set shows how DEC connects between the DLV11-J and a DB25M plug.

Not also that there are other similar-looking panels that are NOT compatible with the DLV11-J, so check the part number or PCB number before using it. For example there is a H3173A (with PCB number 50-15599-01), which appears to be designed for use with DHV11 (terminal multiplexer).

RSX-11M-Plus Manuals and Information

Here are some links to some useful documentation: