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 🙂 .

PDP11 CPU Board – M8186 DEC QBUS

Bought February, 2017, got it from UK, payed 83 british pounds (~91€)

KDF-11-AA 5013326C  

More info on this board is here: http://web.frainresearch.org:8080/projects/pdp-11/dcf11.php

A citation from http://web.frainresearch.org:8080: Either processor would be desirable to own, but the M8189 provides more value. An M8186 would require additional modules with serial ports, boot ROMs and potentially an LTC register to provide a complete system. This could be accomplished by pairing it with a multifunction board, but it would still take up as much or more space as the M8189. In small form factor systems, with an H9281 backplane, the M8186 would be the only choice.

Above is the M8186 board with CPU in the middle and the MME at the bottom.

This is a CPU-Board, as far as I know from a DEC PDP 11/23.

Citing from http://web.frainresearch.org:8080/: The DCF11-based processor is a microcomputer with a 16-bit address bus and a 16-bit data bus. It was used in the PDP-11/23 line of Q-bus computers, and the PDP-11/24 line of UNIBUS computers.

The board contains a KDF11-A CPU, this is the chip with two golden caps. The CPU has date code 81/13, so calendar week 13 1981.
Board number is KDF-11-AA 5013326C , so its a revision C and supports 22-bit addresses.

The CPU hosts two ICs, one is the AMI 303D (23-001C7 AA), the other one is the AMI 302F (21-15541AB) . From Internet, I learned that 303D is the Control Chip, and 302F is the Data Chip. The CPU, code name ‚Fonz‘ runs at 3.6 Mhz, Bus has the same frequency, it has in sum 29.000 transistors.

The other gold cap chip is the AMI 304E Memory Management Unit (MMU) for PDP-11 computers. Complete name of this chip is KTF11-AA MMU 21-15542-00 

22-bit addressing and the existence of the MMU allows to address more than 65KB, maximum is 4MB RAM.

The Quarz oscillator has 13.824 MHz.

All other chips are more or less standard TTL chips.

On the free slots, an FPU (and maybe other chips) can be inserted.

Solder side of M8186 CPU board

and the solder side of M8186.

PDP Backplane – H9278-A

QBus Backplane with 8 Quad slots

Bought February, 2017, got it from US of A, 165 US$ (=161€, uh, expensive, how could I)

H9278 backplane from connector side

It seems possible to mix dual and quad slot cards in the PDP concept. This backplane allows dual and quad cards, so I am on the happy path here.

H9278 backplane from solder side

The backplane comes with 4 connectors in total. 2 of them look like power connectors (these with 4 pins at the top).

There is an inline connector with 18 pins at the right and a small blue connector with 2×5 pins (9 pins used).

The large inline connector with 18 pins is the main power connector. In systems manual, it is called J1.

The small blue connector is a connector that has some signals coming and going to front panel. In systems manual, it is named J2. Some of the contacts are crucial for booting a PDP11 and need to be served with the correct signals on startup. See e.g. here: http://www.diane-neisius.de/pdp11/#atx .

Next steps to do

I plan to set up a minimal system to allow booting the CPU. For that, I want follow these steps

  1. Buy a serial card to connect my PC via RS232. There are many different of these cards available, I look especially for M8047 (because it also offers RAM and ROM option) and M7195. Done!
  2. Provide required RAM/ROM, maybe via a simulation with an AVR or whatever. If I can get a M8047, this card could also provide required RAM/ROM. Another option is to buy an additional RAM card. Done!
  3. Connect everything and boot 🙂

Serial board DEC M8028 DLV-11F

The DEC M8028 module is a Serial Line Unit (SLU). It is a dual sized board, has 18 bit address bus and offers a single serial port. It is console compatible, i.e. can be used as a system console. Maximum baud rate is 9600.

Bought January 2021, from Germany, payed 90€. I bought three modules at once (M8028, M3104, M8067 for all together 270€).


Serial board DEC M3104 – 8 Line serial port

The DEC M3104 module is a serial port multiplexer module. It is a quad sized board, has 22 bit address bus and offers 8 serial ports. Maximum baud rate is 38.400. It uses up to 4.25 ampere at 5 Volts, so it is a quite power-hungry module.

Bought January 2021, from Germany, payed 90€

Memory Board DEC M8067 – 512 MB RAM

The DEC M8067 is a 512MB RAM module. It is a quad size board, requires 22 biserial_smallt address bus. Data width is 18 bits.

Bought January 2021, from Germany, payed 90€

Close look …

Further reading

Online Chips museum PDP11 entry http://silirium.ru/dec-pdp11.html

Frain research on PDP11 – http://web.frainresearch.org:8080/projects/pdp-11/backplanes.php


Diane Neisius page about setting up a PDP11 from parts – http://www.diane-neisius.de/pdp11/