Web site: quanstro.net/plan9/9atom/
Origin: unknown
Category: Desktop
Desktop environment: CLI
Architecture: x86, x86_64
Based on: Plan9
The last version | Released: April 30, 2013

9atom – an operating system based on Plan 9. 9atom (amd64 usb image, 386 iso) augments the Plan 9 distribution with the addition of a 386 PAE kernel, an amd64 cpu and terminal kernel, nupas, extra pc hardware support, IL and Ken’s fs.

“Tt is not polished, but it should contain the basics, be go compatible, contain a copy of nix, be self-compiling, and a few other things that I’ll announce once I have a bit more confidence that I haven’t jobbed the cd.”

The project founder is Erik Quanstrom.


No download is available.



Web site: (not active)
Origin: USA
Category: Server
Desktop environment: CLI
Architecture: VAX-11
Based on: UNIX compatible
Wikipedia: LOCUS
Media: Install
The last version | Released: 1983

LOCUS – a UNIX-like distributed operating system developed at UCLA (University of California, Los Angeles, USA) between 1980 and 1983.

LOCUS is a distributed operating system which supports transparent access to data through a network wide filesystem, permits automatic replication of storaget supports transparent distributed process execution, supplies a number of high reliability functions such as nested transactions, and is upward compatible with Unix. Partitioned operation of subnetl and their dynamic merge is also supported.
The system has been operational for about two years at UCLA and extensive experience in its use has been obtained.

LOCUS is a Unix compatible, distributed operating system in operational use at UCLA on a set of 17 Vax/750’s connected by a standard Ethernets. The system supports a very high degree of network transparency, i.e. it makes the network of machines appear to users and programs as a single computer;
machine boundaries are completely hidden during normal operation. Both files and programs can be moved dynamically with no effect on naming or correct operation. Remote resources are accessed in the same manner as local ones. Processes can be created locally and remotely in the same manner, and process interaction is the same, independent of location. Many of these functions operate transparently even across heterogeneous cpus.

LOCUS also provides a number of high reliability facilities, including flexible and automatic replication of storage at a file level, a full implementation of nested transactions[MEUL 83], and a substantially more robust data storage facility than conventional Unix systems. All of the functions reported here have been implemented, and most are in routine use.

An important part of the LOCUS research concerns recovery from failures of parts of the system, including partition of a LOCUS system into separated but functioning subnetworks.


No download is available.



Web site: cyberospage.sourceforge.io
Category: Desktop
Desktop environment: CLI
Architecture: x86
Based on: MikeOS
Media: Live
The last version | Released: May 2013

CyberOS – a 16 Bit Opensource Operating System, based on MikeOS 4.1. It includes a text-mode dialog and menu-driven interface, and over 60 System Calls, and a Basic Interpreter and Programs like File manager.


No download is available.




Web site: symobi.com
Origin: Germany
Category: Embedded, Mobile, Others
Desktop environment: GUI
Architecture: x86, PowerPC
Based on: µnOS
Media: Install
The last version | Released: 1.2 | October 22, 2006

Symobi (“System for mobile applications”) – a modern and mobile OS. It is based on the µnOS operating system which incorporates the Sphere microkernel. Symobi offers a complete graphical OS environment with services, a graphical user interface, standard programs, and drivers. The operating system is designed for the use in embedded and mobile systems, but is also suitable for other purposes.

Symobi is platform independent by architecture. Hence, it can be deployed on all modern processor architectures. Nevertheless, there is some work to do to really port Symobi to a new hardware platform. But this work is easy to do since only platform specific mechanisms (e.g. MMU) have to be implemented. There are no architectural changes to be made and there is no higher level programming work to do. As a result, Symobi can be ported to a new platform within weeks and to another processor model of an already supported platform within days. This basic ability of Symobi is liked a lot by our customers since it allows them to choose the hardware they really want and need for their application instead of having to choose a hardware fitting the RTOS used.

Valuable Abilities:
– real-time
– small size/footprint
– high provable stability/reliability
– simplicity
– high performance
– small, efficient API
– embeddable

Modern Features:
– multi-core/multi-processor support
– multi-platform
– client/server architecture
– isolated hardware driver architecture
– light-weight multithreading & multitasking
– strongly protected process spaces
– wide-range scalability

Supported Hardware:
– x386 / IA32
– ARM / XScale
– PowerPC


Symobi 1.2 Wave Live Demo i386 9.88MB.iso.zip
md5sum: f8e3aa7d8a6d38eb3240942a90d7b46c

Symobi 1.2 PowerPC Live Demo 5.29MB.iso.zip
md5sum: 0c426f9d8bfd3fe9eabc532c4b92edf3

Symobi 1.2 VMware Image Live Demo 1.3KB.vmx.zip
md5sum: 35d9e6fb9acaa136b92c4a58b5ab963f




Web site: trumpet.com.au/index.php/products/classios.html
Category: Desktop, Others
Desktop environment: CLI
Architecture: x86
Based on: Independent
Media: Install CD
The last version | Released: Alpha2 | March 25, 2008

ClassiOS – an object Pascal operating system. This operating system is built entirely with the Delphi Compiler – even the boot loader. This was achieved by replacing the System.dcu and related units by a custom unit which can run in Ring 0 of the x86 CPU.

Tattam Software is redeveloping the PetrOS® IA32 (x86) OS project.


ClassiOS Alpha1 i386 170KB.iso.zip
md5sum: bc54fb4d1cb2618c3b93dd31df1c9b2b
ClassiOS alpha2 i386 199KB.iso.zip
md5sum: b47f07f5ea9a7265d6fc671c940102f9




Web site: trumpet.com.au/index.php/products/petrosr.html
Category: Desktop, Others
Desktop environment: CLI
Architecture: x86
Based on: Independent
Media: Install
The last version | Released: 1.01 | 2001

PetrOS – a 32-bit operating system for the PC platform, by Trumpet Software International Pty Ltd. It a small, modular, easy to use, and not resource hungry.

PETROS(r) has been created from first principles, allowing it to focus on a small size and a modular approach. It is not intended to create yet another set of instructions and syntax, rather the underlying design concept has been to create a more efficient way of performing similar tasks without the overheads of resource hungry facilities or excessive feature creep.

Some of the primary features of PETROS(r) include:
– A micro kernel of about 100K, allowing much more memory for applications.
– A full working TCP system can be acheived in approximately 200K.
– It is fast loading, fast and easy to run.
– It runs on a 486 and above level of processor.
– It has a minimum memory requirement of 2MB.
– Standard peripherals are built in.
– It is fully multi-tasking.
– It has loadable driver modules.
– It has virtual paged memory.
– It will allow continued use of superceded machine configurations.
– It contains industry standard disk stuctures and executable formats.

Possible Uses:
– POP mail server.
– SMTP mail server.
– Firesock gateway machine.

Installation Instructions:
PETROS(r) is a fully functional operating system, which replaces the functions of MS-DOS or Windows(tm). As such, it will need to install important files on your disk drives that can prevent other operating systems on the same drive from working. You should make adequate backups and emergency recovery disks before attempting to install PETROS(r) to a hard drive that is used by other operating systems.

1. Installing PETROS(r) to run from the DOS prompt.

In order to coexist with other operating systems, PETROS(r) can be started from MS-DOS (native DOS, not a DOS box). If you are in Windows 9x, restart your computer MS-DOS mode. Create a directory (usually “petros”) to save the PETROS(r) files in and use the -noboot option:

C:\>md petros
C:\>cd petros
C:\petros>a:demo.exe -noboot

Once installed, start PETROS(r) from the DOS prompt by typing “pm”:


PETROS(r) will start up and locate the drives and current directory.

2. Installing on a Floppy Disk.

To install PETROS(r) on a floppy disk, first insert a blank formatted disk in the drive. Copy the file “demo.exe” to a temporary directory on your hard drive and then type “demo.exe a: -boot”:

C:\temp>copy a:demo.exe
1 file(s) copied.
C:\temp>demo a: -boot

After the installation has completed successfully, leave the disk in the drive and reboot the system. PETROS(r) will now boot and you will be able to operate from the floppy drive.

3. Installing to a hard drive.

IMPORTANT – The PETROS(r) installer will overwrite any DOS or Windows boot sector with a PETROS(r) boot sector. Make sure you prepare a recovery disk to reinstate the DOS or Windows boot sector. SHOULD THE INSTALL PROCESS FAIL OR FOR SOME REASON PETROS(r) WILL NOT BOOT, YOUR DRIVE MAY BE LEFT INOPERABLE.

NOTE: If you require a multi-boot system we suggest that you install PETROS(r) on a fresh MS-DOS drive partition prepared using fdisk. Only primary partitions can be made bootable. Fdisk can be used to select between different bootable partitions. Programs like Partition Magic can assist in setting up your partitions to be used as a multiple boot system.

To install PETROS(r) to the hard drive, run the install program from the floppy drive:

A:\>demo c: -boot

Fdisk can now be used to make sure the PETROS(r) drive is the active partition to run PETROS(r) remove the floppy from the drive and reboot your machine.


PetrOS Demo 1.01 i386 524KB.zip
md5sum: 7b26d23ffbc0d235659b72b5c57121b8




Web site: sources.vsta.org/forthos/
Category: UNIX-like, Others
Desktop environment: CLI
Architecture: Intel 80386, Motorola 68030
Based on: VSTa
Media: Install
The last version | Released:

ForthOS – a complete, standalone operating system for the PC. It includes command line, compiler, debugger, editor, and filesystem. You can give it a test drive by booting the standalone CD (image provided so you can burn your own). If you like it, you can install it onto a disk partition and boot directly from your hard disk.

ForthOS was the basis for the author’s own experimental software work; unlike many other Forth systems, this one as a real tool in day-to-day use as a part of a larger development. It is a fully standalone system, with a metacompiler used to generate new versions of ForthOS while running under ForthOS.


ForthOS v1 448KB.iso.gz
md5sum: a222bb82a80b97a43ee1b324b95d2d34

ForthOS v2 virtual image disk 717KB.img.gz
md5sum: e19198440177084d85353e19e1c01f13




Web site: pdos.csail.mit.edu/archive/exo/
Origin: USA
Category: Server
Desktop environment: CLI
Architecture: x86
Based on: Independent
Wikipedia: Exokernel
Media: Install
The last version | Released: 06.22.2000 | June 22, 2000

ExOS – an operating system kernel developed by the MIT Parallel and Distributed Operating Systems group, and also a class of similar operating systems.

An exokernel eliminates the notion that an operating system should provide abstractions on which applications are built. Instead, it concentrates solely on securely multiplexing the raw hardware: from basic hardware primitives, application-level libraries and servers can directly implement traditional operating system abstractions, specialized for appropriateness and speed.

The newest exokernel is XOK, which runs on PC hardware, and ExOS, our first library operating system (libos). The ExOS library provides a user-level and extensible implementation of an UNIX operating system. Most UNIX applications like gcc, perl, apache, tcsh, and telnet compile and work without changes using ExOS. Further, measurements of application performance show that ExOS performs at least as well as OpenBSD and FreeBSD and much better when using specialized libos’s. For example, the Cheetah web server built on top of XOK performs eight times faster than NCSA or Harvest and three to four times faster than IIS running on Windows NT Enterprise Edition.

The current exopc distribution contains the entire source tree for the XOK kernel, ExOS library operating system, and assorted user-level programs and tools for building the system. OpenBSD or Linux with libc6 is required to build the system and only certain disk and ethernet controllers are supported. It was written by a variety of people over the past four years under DARPA sponsorship. Currently, the system is still under active development by PDOS at MIT, Greg Ganger’s group at CMU, and Exotec.

Exopc is stable enough to do libos and application development but there are still many bugs and features that have not yet been implemented. Do not expect to compile everything and replace your current system with XOK/ExOS. However, things are progressing rapidly and hopefully with making the sources public the ‘net world at large can help speed development. Any additions or bug fixes are greatly welcomed and will be considered for incorporation into the main source tree.

Copyright (C) 1997 Massachusetts Institute of Technology; some code in this distribution is covered by the GNU General Public License; some files include the following copyright: Copyright (C) 1998 Exotec, Inc. (free).

Primary authors (alphabetical order):
– Hector Briceno
– Dawson Engler
– Greg Ganger
– Rusty Hunt
– John Jannotti
– Frans Kaashoek
– David Mazieres
– Tom Pinckney

Other authors (alphabetical order):
– Josh Cates
– George Candea
– Robert Grimm
– Eric Nygren
– Costa Sapuntzakis
– Yonah Schneidler
– Josh Stults
– Debby Wallach
– Doug Wyatt


exopc 06.22.2000 source 53MB.tar.gz
md5sum: d1c2d45ec4204e61f84b0c8fe783f134




Web site: ecomstation.com
Origin: USA
Category: Desktop
Desktop environment: GUI
Architecture: x86
Based on: OS/2
Wikipedia: eComStation
Media: Install
The last version | Released: 2.2 beta 2 | December 13, 2013

eComStation (eCS) – an Internet enabled platform for business desktop computing. The focus of eCS is to provide an organization with a set of world class business applications and an application engine which can support multiple API sets. eCS is REXX enabled and comes with support for Java, Windows 3.x (limited 32 bit Windows), OS/2 and DOS applications.

The eComStation was released by Serenity Systems and Mensys BV, but it is currently owned and developed by XEU.com.


eComStation Demo EN_US 107MB.iso
md5sum: 4ed608b224261707f8dd4b9779caa952