scmRTOS is a free tiny preemptive Real-Time Operating System intended for use with Single-Chip Microcontrollers. It has very small footprint (from ~1K of NOR Flash for code and 512 bytes of RAM for data). Supported platforms: MSP430, AVR, STM8, Blackfin, ARM7, Cortex-M3, Cortex-M4. This RTOS is written in C++ language.
These details are provided for information only. No information here is legal advice and should not be used as such.