RTEMS is an acronym meaning Real-Time Executive for Multiprocessor Systems. It runs on a wide range of CPU platforms: AMD 29K; Hitachi SH; HP PA-RISC; Intel x86, i960; Motorola m683x0, m680x0, mPPC, mColdfire; MIPS R46x0, SPARC. It has multiple APIs: RTEMS, POSIX-Unix, uITRON. It is written in C, with C++ support. There is a runtime for GNAT called GNAT/RTEMS for embedded Ada applications. An old RTEMS version is written in Ada83, but is for reference use only. No official newsgroups exist yet, but two public mail lists do: rtems-users, rtems-snapshots; see the OAR website. RTEMS is open source, under OAR's own license.