RTEMS is a commercial grade real-time operating system designed for deeply embedded systems. It is a free open source solution that supports multi-processor systems. RTEMS is designed to support applications with the most stringent real-time requirements while being compatible with open standards.
RTEMS has been ported to over a dozen CPU architectures and includes more than 90 Board Support Packages. Pre-built toolsets are provided for various GNU/Linux distributions and MS-Windows.
Different parts of RTEMS are based upon different standards. In addition the Classic API, RTEMS supports most of the POSIX 1003.1b API and uITRON. It includes a BSD TCP/IP stack and various filesystems. It includes support for C, C++ and Ada programming languages.