CortOS is an Embedded RTOS
1. It is a free and open
2. Task switch is very fast
3. Interrupt service routine uses a separate stack
4. Calculate running time of Task 
5. Device application interface (DAI)
6. It is a real-time multitask kernel which accords with CMSIS ( Cortex Microcontroller Software Interface Standard ).
7. <Atmega328> <ARM Cortex-M0> <ARM Cortex-M3> <ARM Cortex-M4 with FPU> <STM8>
8. Platform:
    <1> STM8S-Discovery
    <2> STM32F4-Discovery
    <3> NuTiny-SDK-M058SSAN V2.1
    <4> STM32F103R
    <5> ATMEGA328