Releases and Active Development
  • The current release is 5.3 (download here). Note that this release branch was planned to be 4.12 but significant changes warranted bumping the major number (e.g. 4 to 5). The new release numbering scheme is described here.
  • The previous release series was 4.11 and the last release from that branch is 4.11.3 (download here).
  • The next release branch is planned to be 6. For details and status, visit the Release page. This is the git master.
  • Information on older releases is available here.

What is RTEMS?

The Real-Time Executive for Multiprocessor Systems or RTEMS is an open source Real Time Operating System (RTOS) that supports open standard application programming interfaces (API) such as POSIX. It is used in space flight, medical, networking and many more embedded devices. RTEMS currently supports 18 processor architectures and approximately 200 BSPs. These include ARM, PowerPC, Intel, SPARC, RISC-V, MIPS, and more. RTEMS includes multiple file systems, symmetric multiprocessing (SMP), embedded shell, and dynamic loading as well as a high-performance, full-featured IPV4/IPV6 TCP/IP stack from FreeBSD which also provides RTEMS with USB.

Major decisions about RTEMS are made by the core developers in concert with the user community, guided by the Mission Statement. We provide access to our development sources via a Git Repository (see these Instructions for details). We strive to provide regular, high-quality releases, which we want to work well on a wide range of embedded targets using cross development from a variety of hosts including GNU/Linux distributions, MS Windows, BSDs, Solaris, and Mac OS. We encourage everyone to contribute changes and feedback to RTEMS.

Commercial support is available from US and European companies, and free support comes via the active global community.


August 31, 2017

OAR Corporation will host an RTEMS training session in Huntsville, Alabama, USA. The class schedule is:

Kick Start - November 13, 2017
For information and registration, see...

April 05, 2017

On May 31, 2017, Sebastian Huber (embedded brains GmbH) will present
RTEMS-SMP at the DASIA2017 conference. The presentation's focus will be
the SMP specific extensions and time response scaling.

During the previous years, big efforts have been made to make RTEMS SMP

January 09, 2017

embedded brains GmbH is currently planning two open RTEMS classes "RTEMS Application Development" in Munich/Germany to start on

May 03, 2017


November 27, 2017.

This class has its main focus on application development based on the...

July 26, 2016

OAR Corporation will host an RTEMS training session in November, 2016. The classes are scheduled as follows:

Kick Start - November 14, 2016
For information and registration, see...

October 30, 2015

OAR Corporation will host an RTEMS training session in March, 2016. The classes are scheduled as follows:

Kick Start - March 14, 2016
For information and registration, see...

October 05, 2015

This summer the RTEMS Project had 10 excellent students participate in the Google Summer of Code Program (GSoC).

All of the students were new to RTEMS. We also had three outstanding new mentors: Ben Gras and Cyrille Artho, who are veteran mentors from other projects, and Ed Sutter, who is...

March 11, 2015

After years of development the Magnetosphere Multiscale (MMS) Mission will be launched on March 12 at 10:44 P.M. EDT. MMS consists of 4 identical spacecraft, the main flight computers run RTEMS 4.10 on a radiation hardened Coldfire CPU. You can watch the...

February 10, 2015

The first RTEMS Developers and Users Conference (RDUC 2015) will take place in Munich, Germany from 18.-19 June 2015. See also: http://lists.rtems....

November 18, 2014

The RTEMS Project services have been relocated from OAR Corporation to the Oregon State University Open Source Lab as part of an on going improvement and investment in The RTEMS Project. We thank you for your patience as this complex task was undertaken...

November 18, 2014

The first RTEMS Open Classes of 2015 will be held in January 2015 in Huntsville Alabama. Once again, Joel Sherrill will be teaching the class. The classes are scheduled as follows:

  • Kick Start - January 26, 2015 in Huntsville Alabama: For information and registration, see...