Reading the PROMs from the M8047 MXV11-A Multi Purpose Card

The M8047 MXV11-A Multi Purpose Card board has DEC Boot PROMs, two sockets for up to 2x4 KBytes. I tried to read the data on these >40 years old EEPROMs. For the two PROMs on the board, I could find the DEC part numbers 23-03901-00 and 23-04001-00 on them, which are 6341 Chips with 512x8 Bytes each. These ROMs are MXV 11-A2 Boot ROMs for RX02, RX01, or TU58 With My Batronix Barlino II Eprommer I was able to read out both ROMs (more info on the Eprommer see here.

pdptools - accessing a PDP machine via serial line

To play with my PDP11, I developed some tools to communicate with the PDP. They allow to communicate via serial line and to upload code to the PDP. all2deposit - creates a SIMH deposit file from a Paper Tape Format file or (not yet implemented) a MACRO11 LST file pdpcom - allows to upload deposit file content to a serial attached PDP11, also allows to access ODT (lika a common terminal connection also does) arthur-gill-examples - some nice examples examples - some simple examples Screencast demo session Small video clip where I list some memory content, load an object file, show that is has been loaded to memory and execute it (this simple object file waits for a single char and prints it to console):

DEC PDP11 Rebuild

This document contains information I have gathered when trying to bring some DEC PDP11 boards together to have a “working” system. Summary of boards I have collected some boards in the last years. CPU boards: M8186 LSI-11/23 CPU (C Revision, so capable of 22 bit addressing) RAM boards: M8044 MSV11-DD 32K RAM, 18Bit M8067 512KB RAM, 22 Bit Serial boards: M8028 DLV-11F serial board M3104 serial board Multi Purpose Boards:

Elektronika BK-0011

Elektronika BK0011 is successor of BK0010, same in english. Both use PDP clone-like CPU K1801WM1. The CPU is said to be fully compatible with PDP11 CPUs, but does not implement EIS instructions. See articles in OldComputerMuseum, PDP11 Instruction set CPU runs at 4Mhz. BK0011 has 128KB RAM. Monochrome/Color output via DIN connector. Built-In speaker and (russian) keyboard. Parallel and serial ports. QBUS available at back side of case. Slots for inserting additional option ROMs

Checking a defective memory module with QBone

This post describe my effort to fix a broken M8044 PDP11 RAM module. For tracing down the bug, I’ve used QBone. I own a defective M8044 RAM board. This board came as part of my OBA-11 PDP11. It was obviously checked by DEC, found to be broken and has a red defective badge. Setting up test bed I’ve created a testbed, consisting of: QBone An unused backplane H9278-A with 8 slots The device under test, the M8044 As power supply, I took a 5V/4Ampere power supply from my parts bin +12V (used by M8044) supply comes from a lab power supply First test with QBone: Check if board responses to bus requests QBone has its tests and many features in a single executable.


What is QBone? QBone is a fascinating project by Jörg Hoppe. It is based on a PDP QBus module that can be inserted into any QBus backplane. It implements all features required by the QBus, so this module looks like any other QBus module from the PDP11 perspective. The module integrates a BeagleBone Board (BBB). This is an ARM-based modern computer, like Raspberry PI. The biggest advantage of BBB over Raspi is: that the board contains two separate I/O processors called PRU (Programmable Realtime Unit).

DEC Digital OBA11-MF

DEC Digital OBA11-MF bought in poor condition from ebay. It has no case, has some physical damage. Sold of course as defective. All together this seems to be a kind of “embedded” PDP 11/03 with only a bare minimum of boards and no intention for extending it later on. Maybe used as a control unit in some chemical plant or whatever. here someone has a picture of another device like this.

PDP 11 parts

I own some old PDP11 parts. I try to complete these to have a minimal set of cards to boot the PDP11. This is seen as a long term task and may last several years… Activity was started in February 2017. In January 2021, I have spent 91+161+3*90 = 522€ on that madness, without any results so far :-) . In 2022, I could buy a basic PDP unit, without case and in bad condition.