The Multics DPS8-M CPU simulator created by Harry Reed and Charles Anthony is available for public download. A complete QuickStart installation package is available that provides software, compilers, system source, install scripts, and several initial projects (SysDaemon, SysAdmin, Daemon, etc.) and users. Simulator source code repository, wiki, and forums are hosted at GitLab.
There are mailing lists at SourceForge for developers and users: (Sign up at https://sourceforge.net/p/dps8m/mailman/)
Eric Swenson's useful Wiki document on how to build a Multics simulator and install your own Multics is the most up-to-date information on using the simulator.
(11/29/22) Version 3.0 of the Multics simulator was released, with many improvements.
(07/29/21) Multics Release 12.7 is now available for use on the DPS8M simulator. Eric Swenson is the release coordinator. Changes are discussed on dps8m-users, dps8m-developers, and on Multicians@groups.io. Dan Cross and Doug Wells created a Release 12.7 GitHub repository for the release.
Eric has documented Software Development Procedures for the Multics Simulator for those who wish to submit changes to Multics.
Public Access Multics at ban.ai
Jeffrey Johnson has put up a public Multics site running the simulator at ban.ai, running on Xeon hardware. You can try out Multics with a guest account, or sign up for a full Multics account with persistent storage and access to Multics forums.
You can access the simulated Multics using several mechanisms including SSH. Service is available for free, as-is, with no guarantees. (Jeffrey had to disable direct Telnet access to BAN due to non-stop automated attacks. Mosh, SSH2, Yggdrasil, and cjdns connections are still accepted: see the web page.)
Vintage Computer Faire Northwest 2018
(05/31/18) Charles Anthony gave an hour-long talk about his history with the DPS8/M emulator on Feb 11, 2018, at the Vintage Computer Festival Pacific Northwest 2018; VCF taped the talk and have put it on YouTube.
How to Install and Run a Simulated Multics
Here is a detailed step-by-step cookbook for downloading and setting up your own simulated Multics.
The cookbook is based on Eric Swenson's Wiki mentioned above, and is broken down into instructions for Mac OS X, Linux, or Windows machines, running on Intel (32 or 64 bit) or Raspberry Pi hardware.
What It Can Do
Simulated Multics is a complete multi-user operating system, running on simulated Honeywell DPS8M processors. It can support almost everything the standard release of Multics could ever do -- with the exception of networking.
- Simulated Multics supports multiple languages: PL/I, FORTRAN, COBOL, BCPL, BASIC, APL, LISP, SNOBOL, C, Algol68, and Pascal.
- A simulated Front-End processor lets users log into Multics using a terminal emulator.
- Multiple text editors are provided, including edm, ted, qedx, and Emacs.
- Tape and disk I/O are sinulated to host system files.
- It supports the GCOS simulator (batch and time sharing).
- mail and send_message work.
The daemons run.
- The simulator will output line printed files as .prt files in a configured directory. There is a program (prt2pdf) available that will convert these .prt files to .pdf files.
- Simulated card input and output are provided.
- It can support multiple (Multics) CPUs running on separate host CPUs, if available.
- The simulator supports autocall (dial out) and slave communication channels, and the ability to "dial out" to host/port on the Internet, or route inbound TCP connections to "slave" channels. It is possible to set up Multics-to-Multics and Multics-to-host connections, including IMFT, Kermit, etc.
A community of developers has contributed bug fixes and enhancements to Multics beyond the last version released by Bull. The operating system and commands have been modified to support dates in the 21st century. Several shared systems have provided stable service for months, shutting down only to install new releases.
Harry Reed started a project in 2012 to create a software simulator for the Multics 6180 CPU based on Bob Supnik's SIMH. A GitLab repository for the simulator is available. With major assistance from Charles Anthony, the simulator booted Multics on Saturday 08 November 2014. It has continued to improve since then, with contributions from several other Multicians, including Gary Dixon, Eric Swenson, Olin Sibert, and Daiyu Hurst.
Prior Multics simulator projects such as Michael Mondy's provided useful experience and learning.
At the ACSAC 30 conference in December 2014, Olin Sibert demonstrated simulated Multics to a distinguished audience. He started the simulator on a Mac laptop, booted Multics, wrote a little PL/I program, compiled it, and ran it. A panel of Multicians discussed "Multics: Before, During, After".
(2/17/17) Stephen Jones of the Living Computer Museum in Seattle (currently closed) has posted a video on YouTube of a real 6180 maintenance panel booting the Multics simulator. The panel is connected to a Linux machine by a special board.
Stephen wrote me:
Charles Anthony modified the DPS-8/M emulator code to support the 6180. The panel was put on eBay several years ago and I purchased it. My understanding is that it came from Oakland University. I believe all panels of that system were saved and nothing else. The interface between the emulator, which is running under Linux on intel i7, is serial to a BASYS3 Xilinx that in turn drives two logic boards attached to the panel's wiring harness. All lamps and switches are available to emulator and that includes the scrolls as well. Just about all displays can be achieved at this time (though maybe more later?). The emulator is booted via switches on the front panel set to 024000717200 followed by the initialize button.
The system boots up to idle in just under 2 minutes, which, from what I understand, is blazingly fast. We are reorganizing our 2nd floor exhibit and hope to develop this into an interesting display with an interactive terminal, as well as remote access, at some point in the next few months. We are also *very interested* in hosting Multicians to celebrate Multics sometime this year. More details regarding this to come and we're open to suggestions in terms of significant/convenient dates.
Multics on a Raspberry Pi
[VFS] I have a Raspberry Pi 2, which has a 900 MHz 32-bit quad-core ARM A7 processor. It has one gigabyte of memory, so the simulator, which uses 270 megabytes of memory, doesn't page. The file system is located on a MicroSD card. My current Linux system has six gigabytes cofigured.
[VFS] It runs Multics at an approximate half a MIP speed: performance test results. It's probably close to the first Multics processors we got at Ford. When the simulator is able to support multi-threaded virtual processors, I should be able to configure a four processor Multics system and get increased throughput, since the A7 is quad-core. There is a Raspberry Pi 3 available, which has a 64-bit processor, but still comes with a 32-bit operating system. (While there are 64 bit operating systems for the RPi 3 on the market, none are packaged with the Raspberry Pi. If we hear of anyone installing one and running Multics it we would find out the performance implications.) I suspect it provides better performance, but I have no specific information. (Running the simulator on my MacBook Pro creates a Multics machine with approximately 7 mips performance.)
- Open Source for Multics as of 2000 is hosted at MIT, courtesy of Bull HN.
- DPS8-M Simulator source code repository, wiki, and forums hosted at GitLab. You can clone a copy of the repository to your own computer. It is 152 MB on disk. You can also sign up for several email lists for general discussion and simulator development here. Multics boot tape images are available, based on DOCKMASTER images from bitsavers.org.
- A full how-to for MR12.7 can be found on Eric Swenson's Wiki. This includes the MR12.7_QuickStart.zip and in the MR12.7_artifacts.zip archives, which both include the MR 12.7 boot tape image and FAQ instructions for using KERMIT.
- Multics source Release 12.7 GitHub repository from Dan Cross and Doug Wells. You can clone the repository to have a copy of the entire source of Multics on your own computer. It is 170MB on disk. This archive was created by Doug using mxload; it replaces Multics archive files with subdirectories.
- Adam Sampson has created a repository on GitLab with the sources of all releases we've been able to locate.
- Information about the simulator and how to use it is at RingZero - Multics Reborn.
The Multics bibliography points to much additional documentation for Multics.
- 113 manuals are available online, many at bitsavers.org
- 724 Multics Technical Bulletins are available online
- 3590 other papers and books are available