Linux Kernel source tree
Scalable, optimized, secure RTOS for multiple hardware architectures
Market leading real time kernel for 40+ microcontroller architectures
Real-Time Event Frameworks based on active objects & state machines
Cluster wide IPC providing datagram, connection, and bus messaging
freeRTOS for Arduino Uno, Goldilocks 1284p & Mega 2560
Scripts to build a custom Linux system for 16MB Netpliance I-Opener.
Free real-time operating system designed for microcontrollers
RTOS for Secure, Safe and Real-Time Systems
Open-source RTOS and Embedded Systems Toolkit for C++ and C
Real-Time Embedded Operating System
PRTOS is a simple, compact preemptive RTOS for embedded systems
ext2/3/4 library for microcontrollers
W-Bus communication library
CAN bus device driver
Android, DOS, FirefoxOS, Linux, MacOS and Windows all in one..
A Development Framework for Coldfire