Multics today

Could a simulator be written for a Multics CPU?

It has been done. You can download an open source DPS8M simulator for Multics and install it on a Windows, Macintosh, or Linux machine, and run your own copy of Multics on a simulated mainframe.

Where can I get a Multics account today?

The last site running Multics hardware shut down as of 31 Oct 2000.

(8/18/23) You can request a Multics account on the simulated Gold Hill Multics by sending mail to Eric Swenson. This site is always running the latest software -- it is the integration site from which he produces new releases of Multics. It is currently running MR12.8.

Where can I see some Multics hardware?

The Computer History Museum in Mountain View, CA, USA has the hardware for the DOCKMASTER system on "permanent loan" from the National Cryptologic Museum. The hardware is not on public view, but you might be able to arrange a tour.

(07/02/24) The former Living Computer Museum in Seattle, WA, USA had a 6180 maintenance panel connected to a simulated Multics. You could watch the lights blink. The LCM's Multics artifacts have been granted to the Super Dimension Fortress in Tukwila WA.

I'd like to see some Multics source. How?

Bull HN has made the entire source of Multics available "for any purpose and without fee" at MIT as of November 2007. A GitHub source code repository is online, so you can clone the entire source of Multics to your computer. Source for a few programs is available at this site, cross-referenced to the Glossary.

Could Multics be ported to a modern micro?

Probably. The main issue I see is how to provide the features of 6180 segments that user programs depend on.

Several projects were started to try this in the 80s, as described on the Multics History page. None of these projects finished. Porting Multics would be a big job, and the final product would need further development to match the current state of the art (e.g. web browsers, JPG editors). Paul Green says, "I think it would be easier to try 'improving' existing technology than to resurrect Multics itself."

News Events

See Multics History for historical narrative and the Multics Chronology for historical dates.

Aug 2023: Multics Release 12.8 was released with 80 bug fixes and a few new facilities.

Aug 2023: Version 3.0.1 of the Multics Simulator was released.

Jul 2021: Multics Release 12.7 GitHub source code repository from Dan Cross and Doug Wells for use on the Multics Simulator was released.

Sep 2019: Version 2.0 of the Multics Simulator was released.

July 2019: Professor Fernando J. Corbató passed away on July 12. A memorial event was held on Nov 4 2019 at MIT.

Sep 2018: The Multics History Project Archives were donated to the Living Computer Museum in Seattle. This included 11 boxes of tapes, and 58 boxes of Multics and CTSS documentation and listings. What will happen to these items is unknown.

Feb 2018: Charles Anthony gave a talk on the Multics simulator at the Vintage Computer Festival Pacific Northwest 2018.

July 2017: Version 1.0 of the Multics Simulator was released.

Apr 2017: Version MR 12.6f of Multics was released for use with the Multics Simulator. Eric Swenson's Wiki has the latest software info.

December 2014: The Annual Computer Security Applications Conference (ACSAC) 2014 presented a Distinguished Practitioner Keynote Panel titled "Multics: Before, During, After". Olin Sibert moderated: Roger Schell, Tom Van Vleck, and Steve Lipner were the panelists. The panel talked about the 50-year influence of Multics on computer science and on subsequent systems. Olin demonstrated Harry Reed's Multics Simulator.

November 2014: The late Harry Reed's simulator for the Multics CPU reached a major milestone on Saturday 08 November. The SIMH-based simulator booted Multics MR 12.5, came to operator command level, entered admin mode, created a small PL/I program, compiled and executed it, and shut down. The simulator has also generated a new Multics System Tape boot image, and booted it. A community of Multicians is making bug fixes and extensions to Multics for use with the simulator.

June 2014: Michael Pandolfo has begun the Multics50 Project to prepare for a celebration of the 50th annversary of Multics in 2015 by organizing a volunteer force to

Contact him to participate.

May 2014: MIT held a 50th anniversary celebration of Project MAC/ LCS/ CSAIL in Cambridge, MA on May 28 & 29, 2014. There was also an associated Multicians' reunion event on May 29. A story with photos and links to videos is online.

Dec 2013: Harry Reed's SIMH-based software simulator for the Multics 6180 CPU has progressed to a point where it can run about 30M instruction cycles of the T&D tape.

Mar 2013: Michael Mondy has been working on a Multics CPU simulator for several years. His simulator is able to load a simulated boot tape and run for many instructions before taking a fault in init_empty_root.

Nov 2012: Harry Reed has started a project to create a software simulator for the Multics CPU based on Bob Supnik's SIMH. The purpose of this project is to create an open source simulator reproducing in sufficient detail the function and capabilities of the Honeywell/Bull DPS-8/M processor with the ultimate goal of resurrecting Multics. Harry is interested in finding volunteers to code, debug, document, test, etc. People who understand the workings of the Multics CPU are especially welcome. For information on this project, use the "Wiki" tab on the SourceForge page linked above.

Nov 2007: Open Source for Multics is hosted at MIT, courtesy of Bull HN. It is available "for any purpose and without fee" provided that the copyright notice and historical background are preserved in all copies.

Oct 2000: The Canadian Dept of National Defence machine at MCHQ (Halifax, NS) shut down at 17:08Z on 10/30/00. This is thought to be the last machine running.

Jul 2000: The CGI (formerly Perigon (formerly ACTC)) machine shut down on July 7, 2000.

For more events, see Multics Dates.