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Multics Simulator

Multics Simulator

2023-08-29 02:10:39


Version 3.0.1 of the Multics simulator was launched, with many enhancements.
See DPS8M home page, gitlab web page and Multics Simulator Frequently Asked Questions, Wiki web page.

To put in the DPS8 Simulator and the newest Multics in your machine, see Eric Swenson’s Getting Started, Wiki web page.
This has the steps for putting in the simulator in your machine, and intstalling Multics software program, compilers, system supply, set up scripts,
and a number of other preliminary tasks (SysDaemon, SysAdmin, Daemon, and so on.) and customers.

(08/18/23) Multics Launch 12.8 is now obtainable to be used on the DPS8M simulator, with 80 bug fixes.
Eric Swenson is the discharge coordinator.
Adjustments are mentioned on dps8m-users, dps8m-developers, and on

Eric Swenson has documented Software Development Procedures for the Multics Simulator
for many who want to submit bug fixes and modifications to Multics for the simulator setting.

Designs are described in MTBs. An index is at Post-Honeywell MTBs, MTBs since 2015.

Adjustments are proposed and documented in MCRs. An index is at Post-Honeywell MCRs, MCRs since 2015.

(08/10/14) Simulated Honeywell Multics {hardware} is on the market for Home windows, Linux/Unix, and macOS.
The Multics DPS8-M CPU simulator created by Harry Reed and Charles Anthony is on the market for public obtain.
It simulates a whole Multics mainframe system, with a number of CPUs, I/O controllers, Community Processors, and peripherals.
The simulator can run on AIX, FreeBSD, NetBSD, OpenBSD, DragonFly BSD, Haiku, GNU/Hurd, illumos OpenIndiana, Linux, macOS, Solaris, and Home windows.
The simulator is open supply, obtainable on GitLab.

Mailing Lists

There are mailing lists at SourceForge for builders and customers:
(Join at



Public Entry Multics at Gold Hill Multics

(04/27/23) You’ll be able to request a Multics account on the simulated Gold Hill Multics by sending mail to Eric Swenson.
This website is at all times working the newest software program — it’s the integration website from which he produces new releases of Multics.
It’s at present working MR12.8.

Public Entry Multics at

(05/14/23) From 2018 to the current, Jeffrey Johnson has supplied a public Multics website working the simulator.
the website is at present unavailable, however the simulator continues to be working (and nonetheless has common customers).
The next entry strategies can be found:

  • Principal SSH:
  • Alt. SSH: [password: multics]

The alternate SSH technique helps SSH shoppers that require authentication.

What Simulated Multics Can Do

Simulated Multics is a whole multi-user working system, working on simulated Honeywell DPS8M processors.
It will probably assist nearly every part the usual launch of Multics may ever do — excluding networking.

  • Simulated Multics helps a number of languages: PL/I, FORTRAN, COBOL, BCPL, BASIC, APL, LISP, SNOBOL, C, Algol68, and Pascal.
  • A simulated Front-End processor lets customers log into Multics utilizing a terminal emulator.
  • A number of textual content editors are supplied, together with edm, ted, qedx, and Emacs.
  • Tape and disk I/O are sinulated to host system information.
  • It helps the GCOS simulator (batch and time sharing).
  • mail and send_message work.
  • The daemons run.

    • The simulator will output line printed information as .prt information in a configured listing.
      There’s a program (prt2pdf) obtainable that may convert these .prt information to .pdf information.
    • Simulated card enter and output are supplied.
  • It will probably assist a number of (Multics) CPUs working on separate host CPUs, if obtainable.
  • The simulator helps autocall (dial out) and slave communication channels,
    and the power to “dial out” to host/port on the Web,
    or route inbound TCP connections to “slave” channels.
    It’s attainable to arrange Multics-to-Multics and Multics-to-host connections, together with IMFT, Kermit, and so on.

A neighborhood of builders has contributed bug fixes and enhancements to Multics
past the final model launched by Bull.
The working system and instructions have been modified to assist dates within the twenty first century.
A number of shared programs have supplied secure service for months, shutting down solely to put in new releases.

Simulator Historical past

Harry Reed began a mission in 2012 to create a software program simulator for the Multics 6180 CPU primarily based on Bob Supnik’s SIMH.
A GitLab repository for the simulator is available.
With main help from Charles Anthony, the simulator booted Multics on Saturday 08 November 2014.
It has continued to enhance since then, with contributions from a number of different Multicians,
together with Gary Dixon, Eric Swenson, Olin Sibert, and Daiyu Hurst.

Prior Multics simulator tasks equivalent to Michael Mondy’s supplied helpful expertise and studying.

Public Demonstration 2014

On the ACSAC 30 conference in December 2014,
Olin Sibert demonstrated simulated Multics to a distinguished viewers.
He began the simulator on a Mac laptop computer, booted Multics, wrote a bit PL/I program, compiled it, and ran it.
A panel of Multicians mentioned “Multics: Earlier than, Throughout, After”.

Blinkenlights Exhibit at Residing Laptop Museum

(2/17/17) Stephen Jones of the Living Computer Museum in Seattle (at present closed)
has posted a video on YouTube of a real 6180 maintenance panel booting the Multics simulator.
The panel is related to a Linux machine by a particular board.

Stephen wrote me:

Charles Anthony modified the DPS-8/M simulator code to assist the 6180.
The panel was placed on eBay a number of years in the past and I bought it.
My understanding is that it got here from Oakland University.
I imagine all panels of that system have been saved and nothing else.
The interface between the simulator, which is working underneath Linux on intel i7,
is serial to a BASYS3 Xilinx that in flip drives two logic boards hooked up to the panel’s wiring harness.
All lamps and switches can be found to simulator and that features the scrolls as effectively.
Nearly all shows might be achieved at the moment (although possibly extra later?).
The simulator is booted through switches on the entrance panel set to 024000717200 adopted by the initialize button.

See Also

The system boots as much as idle in just below 2 minutes, which, from what I perceive, is blazingly quick.
We’re reorganizing our 2nd ground exhibit and hope to develop this into an attention-grabbing show
with an interactive terminal, in addition to distant entry, in some unspecified time in the future within the subsequent few months.
We’re additionally *very * in internet hosting Multicians to rejoice Multics someday this yr.
Extra particulars relating to this to come back and we’re open to recommendations when it comes to vital/handy dates.

Simulated Multics on a Raspberry Pi 2017

(3/10/17) Vince Scarafino despatched some good pictures of Multics working on his Raspberry Pi.
The pc is concerning the dimension of a deck of playing cards. He wrote me:

I have a Raspberry Pi 2, which has a 900 MHz 32-bit quad-core ARM A7 processor.
It has one gigabyte of reminiscence, so the simulator, which makes use of 270 megabytes of reminiscence, does not web page.
The file system is situated on a MicroSD card.
My present Linux system has six gigabytes cofigured.

It runs Multics at an approximate half a MIP velocity: performance test results.
It is in all probability near the primary Multics processors we received at Ford.
When the simulator is ready to assist multi-threaded digital processors,
I ought to be capable of configure a 4 processor Multics system and get elevated throughput, because the A7 is quad-core.
There’s a Raspberry Pi 3 obtainable, which has a 64-bit processor, however nonetheless comes with a 32-bit working system.
(Whereas there are 64 bit working programs for the RPi 3 available on the market, none are packaged with the Raspberry Pi.
If we hear of anybody putting in one and working Multics it we’d discover out the efficiency implications.)
I think it offers higher efficiency, however I’ve no particular data.
(Working the simulator on my MacBook Professional creates a Multics machine with roughly 7 mips efficiency.)

Closeup of the pc. (click on for a bigger view)

The display reveals the Multics operator console within the higher proper and a person login within the decrease proper. (click on for a bigger view)

Classic Laptop Faire Northwest Presentation 2018

(05/31/18) Charles Anthony gave an hour-long speak about his historical past with the DPS8/M simulator on Feb 11, 2018,
on the Classic Laptop Pageant Pacific Northwest 2018;
VCF taped the discuss and have put it on YouTube.


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