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This post is about the desktop operating systems that fly under the radar of most people. We are definitely not talking about Windows, Mac OS X or Linux, or even BSD or Solaris. There are much less mainstream options out there for the OS-curious.

• AmigaOS 4.1

This month (September 2008) AmigaOS 4.1 was released. Although AmigaOS is a veteran in the field (many have fond memories of the original Amiga computer), its current version is a fully modern OS.

AmigaOS only runs on specific PowerPC-based hardware platforms. The company ACube is currently marketing and distributing AmigaOS and is going to bundle the OS with their motherboards.

Source model: Closed source

License: Proprietary

Platform: PowerPC

State: Final

Read a review of AmigaOS 4.1 at Arstechnica.

• Haiku

Haiku is an open source project aimed at recreating and continuing the development of the BeOS operating system (which Palm Inc. bought and then discontinued). Haiku was initially known as OpenBeOS but changed its name in 2004.

Haiku is compatible with software written for BeOS.

Source model: Free and open source

License: MIT License

Platform: x86 and PowerPC

State: Pre-Alpha

Read more at the Haiku website. 

• MorphOS

MorphOS is a lightweight, media-centric OS build to run on PowerPC processors. It is inspired by AmigaOS and also includes emulation to be able to run Amiga applications.

Source model: Closed source

License: Mixed proprietary and open source

Platform: Pegasos, some Amiga models, EFIKA

Read more at the MorphOS website.

• AROS Research Operating System

AROS is a lightweight open source OS designed to be compatible with AmigaOS 3.1 but also improve on it. The project was started in 1995 and can today be run on both PowerPC and IBM PC compatible hardware. It also includes an emulator that makes it possible to run old Amiga applications.

Source model: Open source

License: AROS Public License

Platform: x86 and PowerPC

Read more at the AROS website.

• ReactOS

ReactOS is an operating system designed to be compatible with Microsoft Windows software. The project started in 1998 and today it can run many Windows programs well. The ReactOS kernel has been written from scratch but the OS makes use of Wine to be able to run Windows applications.

Source model: Free and open source

License: Various free software licenses

Platform: x86 (more under development)

State: Alpha

Read more at the ReactOS website.

• Syllable Desktop

Syllable is a free and open source operating system that was forked in 2002 from AtheOS, an AmigaOS clone. It’s intended as a lightweight and fast OS suitable for home and small office users.

Source model: Free and open source

License: GNU General Public License

Platform: x86

State: Alpha

Read more at the Syllable website.

• SkyOS

SkyOS is a closed source project written by Robert Szeleney and volunteers. It originally started as an experiment in OS design. It’s intended to be an easy-to-use desktop OS for average computer users. Well-known applications such as Firefox have been ported to run on SkyOS.

Source model: Closed source

License: Proprietary

Platform: x86

State: Beta

Read more at the SkyOS website.

•  MenuetOS

MenuetOS, also known as MeOS, is an operating system written entirely in assembly language which makes it very small and fast. Even though it includes a graphical desktop, networking and many other features it still fits on a single 1.44 MB floppy disk (for our younger readers, that was the USB stick of the 80s and early 90s ).

Source model: Open source (32-bit version), freeware (64-bit version)

License: Menuet License

Platform: x86

State: Beta

Read more at the MenuetOS website.

• DexOS

DexOS is an open source operating system designed to work like the minimalistic ones on gaming consoles, but for PCs. Its user interface is inspired by video game consoles and the system itself is very small (supposedly this one also fits on a floppy disk, like MenuetOS) and the OS can be booted from several different devices. Its creators have tried to make it as fast as possible.

Source model: Free and open source

Platform: x86

Read more at the DexOS website.

• Visopsys

Visopsys is a one-man hobby project by programmer Andy McLaughlin. The development began in 1997 and the OS is both open source and free. Visopsys stands for VISual Operating SYStem.

Source model: Open source

License: GPL

Platform: x86

State: Final

Read more at the Visopsys website.

And here are some great Web operating systems

Stumble it!