What is "rtems"

Real-Time Executive for Multiprocessor Systems (RTEMS), formerly Real-Time Executive for Missile Systems, and then Real-Time Executive for Military Systems, is a real-time operating system (RTOS) designed for embedded systems. It is free open-source software.

Development began in the late 1980s with early versions available via ftp as early as 1993. OAR Corporation is currently managing the RTEMS project in cooperation with a Steering Committee which includes user representatives.