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PDP-10
its
Assembly2017–2026
PDP-10 / its

its

Incompatible Timesharing System

23Distinct people
76Mentions
0Explicit recommenders
963GitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

Incompatible Timesharing System

GitHub

Where it is used

No documented product use was verified in the last source check.

What people are saying

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Also in these discussions

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This week on Hacker News

Nov 8–Nov 15 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/15/2026, 6:59:22 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year76 dated mentions

Observed mentions: 2017-01-24 01:14:25 UTC to 2026-09-12 02:00:03 UTC.

051015202017-01-01 00:00:00 UTC to 2018-01-01 00:00:00 UTC (exclusive): 2 mentions; 1 submissions, 1 comments20172018-01-01 00:00:00 UTC to 2019-01-01 00:00:00 UTC (exclusive): 6 mentions; 0 submissions, 6 comments2019-01-01 00:00:00 UTC to 2020-01-01 00:00:00 UTC (exclusive): 6 mentions; 1 submissions, 5 comments2020-01-01 00:00:00 UTC to 2021-01-01 00:00:00 UTC (exclusive): 9 mentions; 0 submissions, 9 comments2021-01-01 00:00:00 UTC to 2022-01-01 00:00:00 UTC (exclusive): 8 mentions; 1 submissions, 7 comments20212022-01-01 00:00:00 UTC to 2023-01-01 00:00:00 UTC (exclusive): 7 mentions; 1 submissions, 6 comments2023-01-01 00:00:00 UTC to 2024-01-01 00:00:00 UTC (exclusive): 19 mentions; 2 submissions, 17 comments2024-01-01 00:00:00 UTC to 2025-01-01 00:00:00 UTC (exclusive): 11 mentions; 2 submissions, 9 comments2025-01-01 00:00:00 UTC to 2026-01-01 00:00:00 UTC (exclusive): 5 mentions; 1 submissions, 4 comments2026-01-01 00:00:00 UTC to 2027-01-01 00:00:00 UTC (exclusive): 3 mentions; 0 submissions, 3 comments. Incomplete calendar period.2026*

* An incomplete calendar period is marked with an outlined bar. Its count is not directly comparable with a full period.

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
20172017-01-01 00:00:00 UTC2018-01-01 00:00:00 UTC211
20182018-01-01 00:00:00 UTC2019-01-01 00:00:00 UTC606
20192019-01-01 00:00:00 UTC2020-01-01 00:00:00 UTC615
20202020-01-01 00:00:00 UTC2021-01-01 00:00:00 UTC909
20212021-01-01 00:00:00 UTC2022-01-01 00:00:00 UTC817
20222022-01-01 00:00:00 UTC2023-01-01 00:00:00 UTC716
20232023-01-01 00:00:00 UTC2024-01-01 00:00:00 UTC19217
20242024-01-01 00:00:00 UTC2025-01-01 00:00:00 UTC1129
20252025-01-01 00:00:00 UTC2026-01-01 00:00:00 UTC514
2026 (partial)2026-01-01 00:00:00 UTC2027-01-01 00:00:00 UTC303

From the project README

An excerpt from the repository, fetched Nov 13, 2026.

Read the project’s introduction
Incompatible Timesharing System About ITS ITS, the Incompatible Timesharing System, is an operating system for the PDP-10 computer family. It was created by hackers at MIT in the 1960s. The MIT site was shut down in 1990, but enthusiasts continue to operate ITS systems to this day. Some notable ITS features: Hosted the first versions of Emacs, Zork, Macsyma, Maclisp, Scheme, and multi-player Maze War Virtual memory User-space device drivers Networking: TCP/IP, ARPAnet, Chaosnet Transparent network file system Terminal-independent text output Graphical workstations There is a mailing list for discussion about ITS. Go to http://its.victor.se/mailman/listinfo/its-hackers_its.victor.se for more information. About this project This repository contains source code, tools, and scripts to build an ITS system from scratch. The goals are: To provide an automated build from start to end. No user intervention is necessary. To check which programs have source code, and which programs are missing source code. To ensure that we know how to build all programs. To update programs with the latest bug fixes and enhancements. To be able to set configurable options across the whole system, such as host name, IP address, hardware devices. The build currently runs on the SIMH and KLH10 emulators. Of course, we'd be delighted to test this on a real KS10. Building To build ITS with this repository, you need some tools installed; see the table below. Ensure all submodules are checked out, and then type make EMULATOR=simh, make EMULATOR=pdp10-ka, make EMULATOR=pdp10-kl, make EMULATOR=pdp10-ks, or make EMULATOR=klh10. This will leave built files in the out directory, some of which are disk images with ITS installed. Emulator Dependencies klh10 git, c compiler, make, expect, curses, autoconf simh git, c compiler, make, expect, curses, autoconf, sdl2 pdp10-ka git, c compiler, make, expect, curses, autoconf, sdl2, sdl2-image, sdl2-net, gtk3 pdp10-kl git, c compiler, make, expect, curses, autoconf, sdl2, sdl2-image, gtk3 pdp10-ks git, c compiler, make, expect, curses, autoconf, sdl2 Usage To start ITS, type ./start. If you see KLH10#, type go and Enter. If you see the DSKDMP prompt, type its, press Enter, and then ESCG. If you use the pdp10-kl emulator there is no prompt and you need to type ESCL ITS, press Enter, and then ESCG. Eventually, you will see SYSTEM JOB USING THIS CONSOLE. You are now ready to log in, so type CTRLZ. See doc/DDT.md for a list of useful commands. Alternatively to logging in directly in the system console window, which will always be displaying daemon messages, you may prefer to use a separate terminal session for logging in. To do this just run telnet localhost <port> from another shell window and press CTRLZ to log in there. The port should be determined as per this list: Port Type Emulator 10000 TK10 pdp10-ka 10002 Datapoint kludge pdp10-ka 10003 Morton box pdp10-ka 10004 DZ11 simh, pdp10-ks 10007 DTE2 pdp10-kl 10008 DL10 (pdp10-kl in the future?) To shut down ITS, type :lock and then 5down. Log yourself out to avoid the 5 minute grace period: type :logout. When ITS writes SHUTDOWN COMPLETE, it's safe to stop the emulator. Press CTRL\ to escape to the simulator command prompt and quit to close it. If you had a separate telnet user session running you can similarly press CTRL[ and then exit telnet. ITS can optionally use some additional peripheral devices. To attach a simulated GT40 graphics terminal, type ./start gt40. If you run the KA10 emulator, you can use the Knight TV raster display by typing ./start tv11 tvcon. On a TV, type F1 instead of CTRLZ. Here is an overview of the repository: bin - PDP-10 binary files necessary to bootstrap the system. build - build scripts. conf - configuration for building ITS. doc - documentation, most of which appear in the INFO system. src - source code for ITS and all programs. tools - build tools. out - build output. user - optional user files installed in ITS. Terminal Emulators Several emulators for terminals and peripheral processors are built along with ITS. They can be started conveniently with the start script, or separately. Not all terminal emulators are set up to work with all PDP-10 emulators by default. Name Description Type klh10 pdp10-ka pdp10-kl pdp10-ks simh type340 Type 340 vector no yes no no no gt40 GT40 PDP-11 vector no yes no yes yes imlac Imlac PDS-1 vector no yes no no no simh_imlac Imlac PDS-1 vector no yes no no no tv11 Knight TV PDP-11 cpu no yes no no no tvcon Knight TV console raster no yes no no no datapoint Datapoint 3300 text no yes no no no vt52 VT52 text no yes yes yes yes tek Tektronix 4010 vector no yes yes no no Documentation See the doc subdirectory for documentation. There are some short introductions for beginners: How to create a new user DDT cheat sheet for Unix users Basic editing with EMACS TECO survival guide DDT debugging newbie guide Hello MIDAS Hello Maclisp Introduction to Muddle DUMP and itstar Games Printing Assembling ITS Com link mode Logo PDP-6 Networking A list of known ITS machines. How ITS is built. Applications Some major applications: Adventure, game C10, C compiler CLU, programming language. DDT, debugger Emacs, editor Logo, interpreter Mac Hack VI and Tech II, chess programs Maclisp, interpreter and compiler Muddle, interpreter Macsyma, symbolic math Maze War, game Midas, assembler Muscom and musrun, for playing music PDP-11 simulator Scheme, interpreter Spacewar!, game Stanford University Drawing System TECO, editor TOPS-10 and WAITS emulator There is a detailed list of all installed programs.
Read the full README on GitHub

What Hacker News says

8 sources
Thank you for that! Here's some more stuff I posted before in this previous discussion about the history of Logo: History of Logo: https://escholarship.org/uc/item/1623m1p3 HN Discussion: https://news.ycombinator.com/item?id=23052300 Comments: https://news.ycombinator.com/item?id=23054174 Here is the source code to LLogo in MACLISP, which I stashed from the MIT-AI ITS system. It's a fascinating historical document, 12,480 lines of beautiful practical lisp code, defining where the rubber meets the road, with drivers for hardware like pots, plotters, robotic turtles, TV turtles, graphical displays, XGP laser printers, music devices, and lots of other interesting code and comments. https://donhopkins.com/home/archive/lisp/llogo.lisp Lars Brinkhoff got some of this code to run in MacLisp on an emulator! (I don't know how much of the historica
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l hardware the emulator supports yet, but he's probably worked on some of that too. ;) ) https://github.com/PDP-10/its/issues/620 Thanks to Lars, here are two revisions of an AI Lab memo about LLOGO: http://bitsavers.org/pdf/mit/ai/aim/AIM-307.pdf http://bitsavers.org/pdf/mit/ai/aim/AIM-307a.pdf And a Logo manual and glossary of PDP-11 Logo: http://bitsavers.org/pdf/mit/ai/aim/AIM-313.pdf http://bitsavers.org/pdf/mit/ai/aim/AIM-315.pdf http://bitsavers.org/pdf/mit/ai/aim/AIM-315a.pdf https://news.ycombinator.com/item?id=23054236 Lars Brinkhoff suggests that this thread comp.lang.logo with Brian Harvey and Leigh Klotz is required reading: https://groups.google.com/forum/#!topic/comp.lang.logo/UqOvE... Just a couple highlights from a detailed history of Logo that Brian and Leigh and others posted: >From Brian Harvey: >Many, many people have been involved in the development of Logo. >Wally Feurzeig started the whole thing by organizing a group at Bolt, Beranek, and Newman, Inc., to study the educational effects of teaching kids a programming language. The first language they used, like most programming languages, was focused on numeric computation, and it was Wally's idea that kids would find it more natural to work in an area they knew better, namely natural language; therefore, he set up a team to design a language featuring words and sentences. Wally made up the name "Logo." >The team Wally put together at BBN included Seymour Papert and Dan Bobrow. The three of them are credited as the designers of the first version of the language; Dan wrote the first implementation. In a BBN report dated August, 1967, credit for additional work is given to Richard Grant, Cynthia Solomon, and Frank Frazier. >Seymour later started a Logo group at MIT, where Logo development continued. The MIT versions of Logo were substantially different from the BBN ones, both in the notations used and in the things the language could do. Most notably, turtle graphics was added at MIT. >Among the many people who contributed to the development of Logo at MIT, at the risk of leaving someone out, are Hal Abelson, Paul Goldenberg, Dan Watt, Gary Drescher, Steve Hain, Leigh Klotz, Andy diSessa, Brian Silverman... oh, lots of people. >I think that most of the early documents are out of print now, but whatever documentation there is of the early efforts will be in the form of technical reports from BBN and from MIT. You may have to visit Cambridge to find them! >From Leight Klotz: >In the mid 1970's, when the AI Lab Lisp Machine project was just getting underway, Marvin Minsky and Danny Hillis (later to found Terrapin, and still later, Thinking Machines) put together a project to build a Logo machine. It had two components: a PDP-11 processor (the 3500) and a separate vector-graphics display (the 2500). Guy Montpetit, a Canadian entrepeneur, funded development eventually, and a company called General Turtle was formed. General Turtle built and sold the 2500/3500 system. Henry Minsky, then about 12, worked on the design of the 2500, using the Stanford Draw program, one of the early electronics CAD systems. (The 2500 had this really great barrell shifter stolen from the Lisp machine design, but it was later found not to work, so it was never used.) [...] >[...] Like Brian, I've left out many people who worked on Logo over the years: Brian Fox and Flavio Rose worked for me at Terrapin on a contract basis briefly, as did vagabond programmer Devon McCullough (who used to dial in with a 300 baud modem he'd written in entirely software using the parallel game port, with an 80-column mixed-case display done with 3x5 pixel characters; when the modem detected the call waiting click on the line, it would make the Apple II speaker make the telephone ringing sound -- a feature which I just saw a US patent filed on, not by Devon.), and the frustrated Sinclar QX programmer, who I suspect doesn't want his name used. Of course, there were tons more people at the AI Lab in the pre-commercial days... >From Lars Brinkhoff >Hello, >I'm mostly researching PDP-10 software, especially MIT's Incompatible Timesharing System. >I have recently stumbled across some of the LOGO group work. I have a copy of the Dazzle Dart game that ran on their PDP-11/45. It uses the Tom Knight vector display controller, so it's not easy to run it. >Maybe it would be possible to get the original MIT PDP-11 LOGO running. >[...] It's running now. >[...] Now also BBN PDP-10 Logo, MIT CLOGO, MIT Lisp Logo, and hopefully soon MIT Apple II Logo (direct ancestor of Terrapin Apple II Logo). https://news.ycombinator.com/item?id=23058440 Terrapin Logo for the Apple ][ and C64 came with a 6502 assembler written in Logo by Leigh Klotz, that they used to write Logo primitives (for controlling the turtle, etc). It would be ambitious to make a self hosting 6502 Logo meta assembler, by porting the entire 6502 assembly language Logo source code to the 6502 Logo Assembler! Leigh, wasn't the assembler that you used for the original Apple ][ version of Logo written in MacLisp running on a PDP-10? The Apple II Source Code for the LOGO Language Found (adafruit.com) 379 points by mmastrac on Oct 4, 2018 | hide | past | web | favorite | 89 comments https://news.ycombinator.com/item?id=18142287 https://blog.adafruit.com/2018/10/04/the-apple-ii-source-cod... Lars: The link in the article to the code from https://github.com/PDP-10/its is broken. I found a few references to it in the repo. Did you have to take it down, or did you move it somewhere else? https://github.com/PDP-10/its/tree/master/src/aplogo >Logo >"I too see the computer presence as a potent influence on the human mind. I am very much aware of the holding power of an interactive computer and of how taking the computer as a model can influence the way we think about ourselves. In fact the work on LOGO to which I have devoted much of the past years consists precisely of developing such forces in positive directions." >Seymour Papert >"Logo is the name for a philosophy of education and for a continually evolving family of computer languages that aid its realization." >Harold Abelson >"Historically, this idea that Logo is mainly turtle graphics is a mistake. Logo’s name comes from the Greek word for word, because Logo was first designed as a language in which to manipulate language: words and sentences." >Brian Harvey >Logo was initially created by Wally Feurzeig, Seymour Papert, Daniel G.Bobrow, Cynthia Solomon and Richard Grant in 1967 as part of a National Science Foundation sponsored research project conducted at Bolt, Beranek & Newman, Inc., in Cambridge, Massachusetts. In 1969 Dr. Seymour Papert started the Logo Group at the MIT Artificial Intelligence Lab. Throughout the 1970s the majority of Logo development was conducted at MIT in the Artificial Intelligence Lab and the Division for Study and Research in Education, using large research computer systems, such as ITS powered PDP-10. >Our goal is to make that early Logo systems available to a wider audience of enthusiasts for exploration, experimenting and, of course, hacking. [...] >MIT APLOGO >In accordance with Leigh L Klotz Jr., Hal Abelson directed the Logo for the Apple II project at MIT. >MIT APLOGO was developed by Stephen Hain, Patrick G. Sobalvarro and Leigh L Klotz Jr. It was developed and cross-compilled for the Apple-II-Plus Personal Microcomputer on PDP-10 at the MIT LOGO Group. It is direct predecessor for Terrapin Logo. We have a source code for assembling an improved version from 7/9/81 at its/src/aplogo
In Byte Magazine Volume 07 Number 08 – Logo (1982)
>There are still a lot of DOS applications in production (particularly in industry) as well as a massive retro gaming community. True but for that your don't need a pkg-manager, and for retro gaming..i would argue that 99.99% use DosBox, and the 0.01% with real hardware use probably MS-Dos 6.22. >anyone still using it outside of hobby communities? I don't think, but we never know ;) The last real hardware was shutdown in 2000 in Canada: https://en.wikipedia.org/wiki/Multics#Project_history >But the release notes for MR12.7 reads more like that of FreeBSD or similar. What do you mean with that? >what language would they be coding in? B? BCL? First it was PLE then PL/1 well and some assembly, in Mutltics tradition the language the OS had to be implemented was written in stone before the langspec. or a working compiler existed (PLE E stands
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for early PL) BTW: The opposite to Multics the "Incompatible Timesharing System" gets some Maintenance-(love) too: https://github.com/PDP-10/its
In Multics MR12.7 released
Here's the source code for Kent Pitman's "DOCTOR" in MACLISP, which was of course inspired by ELIZA. (Joseph Weizenbaum taught Kent Pitman LISP!) https://github.com/PDP-10/its/blob/master/src/games/doc.102 And here's what happened with he (manually by typing) hooked it up with Kenneth Colby's "PARRY" (the paranoid patient): https://www.maclisp.info/pitmanual/funnies.html >Parrying Programs >I didn't write the original ELIZA program, although my Lisp class was taught by Joseph Weizenbaum, who did. I later wrote a very elaborate program of similar kind, which I just called DOCTOR, in order to play with some of the ideas. >At some point, I noticed there was a program at Stanford called PARRY (the paranoid patient), by Kenneth Colby. I understand from Wikipedia's PARRY entry that Weizenbaum's ELIZA and PARRY were connected at one point, altho
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ugh I never saw that. I never linked PARRY with my DOCTOR directly, but I did once do it indirectly through a manual typist. Part of my record of this exchange was garbled, but this is a partial transcript, picking up in the middle. Mostly it just shows PARRY was a better patient than my DOCTOR program was a doctor. >I have done light editing to remove the typos we made (rubbed out characters were echoed back in square brackets). >Also, I couldn't find documentation to confirm this, but my belief has always been that the numeric values after each line are PARRY's level of Shame (SH), Anger (AN), Fear (FR), Disgust (DS), Insecurity (IN), and Joy (J).—KMP [...]
In Joseph Weizenbaum’s Original ELIZA

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