Screen shot of emulator
Screen shot of emulator

OS-9 Multi-user System

This emulator implements a OS-9 Level I operating system with two terminals, a printer and a 6 GB harddisk. Instead of launching Shell at start up, it starts Login on terminal /T1 and TSMon on /T2. You can log in on any of the terminals and try what it was like to use OS-9 as a multi-user system.

How to run it

This is a Java 8 or higher program. Download the JAR and the OS9.dsk files and type: java -jar os9multi-X.Y.Z.jar, where X, Y, and Z correspond to the version numbers.

Source code

The emulator is the 'genericos9' emulation in the OSNINE GitHub project. Send me a Pull Request if you make some improvements.

Change log

Version 2.0.0 - 2020-03-07
New terminal emulation code. Jar size is now 500 kB smaller!
Uses /term and /t1 for more compliance with conventions.
Version 1.1.0 - 2019-11-14
Disks can be changed from the Devices menu.
Can read headerless (DSK) as well as the VDK format from the PC-Dragon emulator.
New command line options: extra arguments are assumed to be disks to load into drive 0 and drive 1.
Version 1.0.0 - 2019-10-27
Initial release



The system uses the kernel from CoCo/Dragon 64. The terminals and printer are implemented as emulated 6850 ACIAs. The harddisks are implemented as a pseudo device where the issues of spin up, rotational delay, noise etc. are removed. Additionally, there is a clock device, which gets the time from the host. The CPU is interrupted 50 times a second to facilitate multitasking.

If you want to put some files on the disk image, then the 'os9' command in the ToolShed package is recommended.