The AROS Research Operating System is an effort to implement an Open Source and portable operating system that is compatible with AmigaOS(TM). Originally, it was meant as a direct reimplementation, but already has features not existing in AmigaOS.
Free operating system for Atari computers, and more.
EmuTOS is a TOS compatible operating system for Atari ST series computers, and more. It is made from Digital Research's GPLed original sources and is a free and open source alternative to Atari proprietary ROMs.
LuninuxOS is a Debian/Ubuntu based Linux distribution.
LuninuxOS is a Debian/Ubuntu based Linux distribution designed to be beautiful, clean, simply, fast, and stable. it was previously known as Sn0wl1nuX. It is super-fast, great-looking, secure, intuitive operating system that powers desktops and laptops. LuninuxOS is absolutely free, and comes with a selection of the best applications designed to meet most of your daily needs. It can be run directly from a CD/DVD/USBStick and optionally be installed to a HDD, including IDE, SCSI, SATA, PATA and USB drives.
Simplest kernel for cooperative multithreading
Simplest of possible ways to multithreading on the smallest microcontrollers. This project is demonstration the programming technique of the multithreading with polling the system state. Published code debugged and ready to use in your projects.
Real time embedded multi-thread kernel
This project is now in the research and development stage. It is intended for very small microcontrollers with a single processor and represent simple multithreading kernel what written by C language. In near time is planning create implementations for AVR and STM8.
Alternative operating system for x86 computers
Visopsys is an alternative operating system for PC compatible computers. In development since 1997, this system is small, fast, and open source. It features a simple but functional graphical interface, pre-emptive multitasking, and virtual memory. Though it attempts to be compatible in a number of ways, Visopsys is not a clone of any other operating system. You can demo the distribution from a “live” CD/DVD or floppy disk
WiBuntu is an Open source, Operating System based on Ubuntu.
WiBuntu is a Operating System based on the Linux Operating System, Ubuntu. WiBuntu OS focuses on Security, Simplicity, Familiarity and Usability. Our goal is to make Linux a more awesome Operating System than currently is using the best, most useful programs that everyone wants but not the things you do not need and we also thrive in giving you more choice and piece of mind by giving you all the desktops for Ubuntu that co-operate with each other rather than breaking each other. Right now, Linux mostly consists of features that make it very hard to be infected by viruses.
open source analogue of IBM OS/2 operating system