The Serenity Operating System
A secure embedded operating system for microcontrollers
Free real-time operating system (RTOS) for microcontrollers
Function pointers queues classes library for Arduino
Real-Time Event Frameworks based on active objects & state machines
Multitasking ARMv7-R and ARMv7-A (Cortex-R, Cortex-A)
Free cooperative operating system designed for microcontrollers
Free real-time operating system designed for microcontrollers
RTOS for Secure, Safe and Real-Time Systems
x86-64 os made in crystal
A Java VM for ARDUINO and other micros using the leJOS runtime.
PRTOS is a simple, compact preemptive RTOS for embedded systems
AquilaOS: UNIX-like Operating System
An operating system for tenputer
An educational operating system written in C#
Tiny operating system for running HCFSM-based systems