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Title: Rtems  
Author: World Heritage Encyclopedia
Language: English
Subject: Real-time operating systems, ITRON project, PikeOS, POSIX, PowerPC
Collection: Arm Operating Systems, Embedded Operating Systems, Real-Time Operating Systems
Publisher: World Heritage Encyclopedia


Developer OAR Corporation
Written in C
OS family Real-time operating systems
Working state Current
Source model Open source
Latest release 4.10.2 / December 13, 2011 (2011-12-13)
Latest preview Git head
Marketing target Embedded systems
Platforms ARM, Blackfin, ColdFire, TI C3x/C4x, H8/300, x86, 68k, LatticeMico32, MIPS, Nios II, PowerPC, SuperH, SPARC, ERC32, LEON, Mongoose-V
License Modified GPL
Official website .org.rtemswww

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating system (RTOS) designed for embedded systems.

The acronym RTEMS initially stood for Real-Time Executive for Missile Systems, then became Real-Time Executive for Military Systems before changing to its current meaning. RTEMS development began in the late 1980s with early versions of RTEMS 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.


  • Design 1
  • Architectures 2
  • Uses 3
  • License 4
  • See also 5
  • References 6
  • External links 7


RTEMS is designed for real-time, embedded systems and to support various open API standards including POSIX and µITRON. The API now known as the Classic RTEMS API was originally based upon the Real-Time Executive Interface Definition (RTEID) specification. RTEMS includes a port of the FreeBSD TCP/IP stack as well as support for various filesystems including NFS and the FAT filesystem.

RTEMS does not provide any form of memory management or processes. In POSIX terminology, it implements a single process, multithreaded environment. This is reflected in the fact that RTEMS provides nearly all POSIX services other than those which are related to memory mapping, process forking, or shared memory. RTEMS closely corresponds to POSIX Profile 52 which is "single process, threads, filesystem".[1]


RTEMS has been ported to various target processor architectures:


RTEMS is used in many application domains. The EPICS community includes multiple people who are active RTEMS submitters. RTEMS is also popular for space uses since it supports multiple microprocessors developed for use in space including SPARC, ERC32 and LEON, MIPS Mongoose-V, Coldfire, and PowerPC architectures, which are available in space hardened models. RTEMS is currently orbiting Mars as part of the Electra software radio (see Mars Reconnaissance Orbiter).[2]


RTEMS is distributed under a modified GPL licence, allowing linking RTEMS objects with other files without requiring the full executable to be covered by the GPL. This license is based on the GNAT Modified General Public License with the language modified to not be specific to the Ada programming language.

See also


  1. ^ "Open Group pilots embedded real-time POSIX conformance testing". Archived from the original on 2013-01-03. 
  2. ^ "Real Time Mars Approach Navigation aided by the Mars Network" (PDF). NASA. Retrieved 2008-01-25. 

External links

  • Official website
  • Official RTEMS Wiki
  • Brazilian RTEMS Community
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