# Incompatible Timesharing System
[](https://travis-ci.org/PDP-10/its)
[](https://gitlab.com/PDP-10/its/commits/master)
### 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](https://github.com/PDP-10/its/issues/61).
- 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.
### Usage
To build ITS with this repository, you need some tools installed:
make, C compiler, and expect. For KA10, you also need SDL or SDL2 for
the Type 340 display. Ensure all submodules are checked out, and then
type `make EMULATOR=simh`, `make EMULATOR=pdp10-ka`, `make
EMULATOR=pdp10-kl`, or `make EMULATOR=klh10`. This will leave built
files in the `out` directory, one of which is a disk image with ITS
installed.
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](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 seperate terminal session for logging in. To do this just
run `telnet localhost 10003` from another shell window and press
CTRLZ to log in there.
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 similary
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 | simh
| ------- | ----------------- | ------ | ----- | -------- | -------- | ----
| type340 | Type 340 | vector | no | yes | no | no
| gt40 | GT40 PDP-11 | vector | no | yes | no | yes
| imlac | Imlac PDS-1 | vector | no | yes | no | no
| simh_imlac | Imlac PDS-1 | vector | no | yes | no | no
| tv11 | Knight TV PDP-11 | cpu | no | yes | no | no
| tvcon | Knight TV console | raster | no | yes | no | no
| datapoint | Datapoint 3300 | text | no | yes | no | no
| vt52 | VT52 | text | no | yes | yes | yes
| tek | Tektronix 4010 | vector | no | yes | yes | no
### Documentation
See the [`doc` subdirectory](doc) for documentation.
There are some short introductions for beginners:
- [How to create a new user](doc/new-user.md)
- [DDT cheat sheet for Unix users](doc/DDT.md)
- [Basic editing with EMACS](doc/EMACS.md)
- [TECO survival guide](doc/TECO.md)
- [DDT debugging newbie guide](doc/debugging.md)
- [Hello MIDAS](doc/hello-midas.md)
- [Hello Maclisp](doc/hello-lisp.md)
- [Introduction to Muddle](doc/muddle.md)
- [DUMP and itstar](doc/DUMP-itstar.md)
- [Games](doc/games.md)
- [Printing](doc/printing.md)
- [Assembling ITS](doc/NITS.md)
- [Com link mode](doc/comlink.md)
- [Logo](doc/logo.md)
- [PDP-6](doc/pdp6.md)
- [Networking](doc/networking.md)
A list of [known ITS machines](doc/machines.md).
How [ITS is built](doc/build.md).
### Applications
Some major applications:
- Adventure, game
- C10, C compiler
- 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](doc/programs.md).