PDP-11 Q-bus Information Page
Overview
I first created this area in September of 2014 to provide information for DEC Q-bus system builders, like myself, who want a single site that provides module comparisons and information on best practices.
I had wanted own a PDP-11 for some years, and like many, my intent was to eventually get Unix running on it. I was somewhat familiar with UNIBUS systems, but consider these machines impractical to own, due to their size, complexity, and power and cooling requirements. The ongoing maintenance would also likely consume more of my time than I would want. Also, because all of the early Unix development was done on UNIBUS systems, I never really paid much attention to the Q-bus products.
One evening, while surfing the web for something completely unrelated, I stumbled across Diane Neisius' PDP-11 Page. After seeing her LSI-11/2-based system and the tinkering she has done, I became fascinated with Q-bus systems. In researching these systems, I had difficulty in finding good comparisons between components, and the information that was available was fragmented.
To aid in my research, I created this area to navigate through all of the components and to help those, who want to build their own PDP-11 system, determine which components they would need. Fortunately, original DEC documentation is easy to come by and provided most of the information found here. One site that was a huge help was VaxHaven which has done a great job of obtaining and organizing most of the available DEC documentation. Of course, the greatness of Al Kossow's Bitsavers was a huge help, as well.
My point-of-view is that of a hobbiest, rather than a historical preservationist. Therefore, in my summaries of the items in these pages, I tend to value components according to their usefulness, which may run counter to the view of others.
The links on the left contain my comparisons of various component groups and their different capabilities. In addition, other articles will be provided to help clarify murky topics.
This site is still very much a work in progress and I plan to add to it regularly. My goal was to build a PDP-11 of my own. When researching and shopping for components I refer to these pages quite regularly. Hopefully, the information provided here is accurate, and will be equally as helpful to others.
Updates
February 5, 2022
- Started the task of adding photos of some of the modules. The first are of the LSI-11 series processors.
Jaunary 26, 2022
- Finally got around to adding Dhrystone and Whetstone values for the M7554-04 DECserver 550 CPU.
July 25, 2020
- Made available the KXT11-A2 Macro-ODT firmware for the M8063 SBC-11/21 module.
July 11, 2020
- Added information on the available boot ROMs for the KDJ11 series CPUs.
- Added to the Disk Controllers page.
- Cleaned up the structural outline of most of the pages.
February 23, 2020
- Updated the Asynchronous Serial Module Multiplexers section, to add introduction dates, onboard processor capabilities, clarification on modem control capabilities and the AC and DC loads for the DZV11. Revised the summary.
- Revised the pages on this site to conform with the latest XHTML best practices.
July 21, 2019
- Updated the 16-bit memory section to correct an error regarding the MSV11-C address width. This board has an 18-bit address width, rather than the previously stated width of 16-bits.
May 11, 2019
- Updated the DCT11 Processor page and revised the references section to include the user's guide for the KXT11-AB board.
- Added AC bus loads to the H9281 backplane table.
May 6, 2019
April 7, 2019
- Made a minor update to change the H9270-A backplane part number to H9270. The H9270-A is an H9270 with a cable trough bolted to the bottom.
- Added a parts table listing the various DCJ11 chipset variations.
June 10, 2018
- Added the MRV11-AA board to the ROM Modules section.
- Cleaned up a couple of items in the RAM Modules section to reflect other updates to this site, and to make it a litte more coherent.
March 2, 2018
- Updated the introductory and retirement dates for the DCT11 Modules, and added a manual reference for the M7676.
February 3, 2018
- Reworked the introductory paragraph of the RAM Modules section.
- Added some memory access times to the RAM Modules tables.
- Added the MMV11-A module to the RAM Modules 16-bit memory table.
December 10, 2017
- Added a new section on DEC tape couplers.
September 3, 2017
- Added benchmarks for DCJ11 processors with PMI support.
August 26, 2017
- Standardized my benchmarking methodology, using a BA11-S chassis, the power line LTC enabled, MSV11-P memory, and 2.9BSD in single-user mode. Revised the Dhrystone and Whetstone benchmarks on the DCF11 and DCJ11 processors, based on the above configuration.
February 18, 2017
- Cleaned up the narrative on the RAM page to make it a little more coherent.
- Added the MCV11 memory modules to the list of other modules with memory.
February 13, 2017
- Added a little more background narrative to the LSI-11 processor page.
- Updated footnote 8, regarding the processor clock, and added footnote 10, regarding memory refresh, to the initial comparison table.
January 2, 2017
- Added information on compatible EPROMs for the PDP-11/23+ processor.
November 26, 2016
- Corrected an error in the Camintonn memory area, in which the specs for the CMV-254 and CMV-500 modules were swapped. I swapped the part number in the table and left everything else the same.
- Added power, bus loads and transfer rates to the Emulex controller table, under Third-Party Products. Cleaned up some of the information in the Summary section.
November 20, 2016
- Corrected an error below from the October 11 revisions, in which I incorrectly referenced DEC MicroNote 45 instead of MicroNote 15.
October 25, 2016
- Corrected a couple of model and version number errors in the DCF11 ROM table, There are some thoughts that a KDF11-BF ROM version exists as V0.9, but V0.9 identifies itself as KDF11-BE, as does V0.8.
October 11, 2016
- Changed the ROM part numbers for the KDF11-BE modules. There seems to be a bit of confusion regarding what these part numbers should be. The KDF11-B CPU System Maintenance manual says they should be 23-238E4 and 23-239E4, but MicroNote 17 and MicroNote 15 say they are 23-157E4 and 23-158E4, and I have verified these, so this is what I have listed.
- Re-wrote the introduction to the third party disk controller section to make it a little more coherent.
- Clarified the H9270 uses.
October 2, 2016
- Corrected an error regarding termination in the H9276 backplane. Clarified the backplane termination rules for a single box system.
October 1, 2016
- Eliminated the KDF11-BE module number from the DCF11 processor table, and clarified the other M8189 module numbers in another section.
September 18, 2016
- Corrected the Dhrystone values for the DCF11 and KDJ11-A processors. These values were off, due to a difference in the compiled in LTC value, and the actual system LTC frequency.
August 30, 2016
- Corrected the amperage values for the 18-bit memory and 16-bit memory modules. Removed some unnecessary rows from the tables.
- Added a little more background information to the introduction of the DCF11 page.
August 29, 2016
- Corrected the +5V amperage values for the 22-bit memory modules. I discovered the discrepancies, while measuring the actual power draw of my PDP-11, and comparing it to the estimated values.
August 20, 2016
- Added the updates section to this page. I should have done this earlier.
- Updated several of the CMD controller specs on the third-party disk controller page.
- Added some Drhystone 2.1 and Whetstone 2.1 benchmark information on the DCF11 processor page.
- Added some Drhystone 2.1 and Whetstone 2.1 benchmark information on the DCJ11 processor page.
- Added an Ethernet controller comparison page.
