Unison, Version 4 for ARM Cortex-M3 processors is an ultra-tiny real-time OS (RTOS) compatible with embedded versions of Linux and POSIX operating systems and the applications running on them.
Unison OS and Stellaris MCUs are installed in a range of home and industrial automation, power management and networking applications. They are designed to save original equipment manufacturers design and manufacturing resources by allowing them to add intelligence to their products without designing the processors and operating systems themselves.
The Stellaris development kit comes with more than 20 Unison demo programs and support for a variety of networking, I/O and file-systems.
Unison V4 runs on Windows XP and Vista for x86 platforms. Open-source licenses start at $695.