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.


November 12, 2012

Google has announced the participating organizations for the 2012 edition of Google Code In. This is a program
for high school students and you should pitch this to your local high...

July 23, 2012

The RTEMS Project is proud to announce that we have been selected for a second year to be a participating organization in the European Space Agency's Summer of Code in Space. Julien Delange posted this invitation to the RTEMS mailing lists. A list of projects is available at...

April 30, 2012

Julien Delange has written an article about real-time operating systems programming which is featured in issue number 149 (index and...

April 30, 2012

The RTEMS Project was accepted for the fifth year as a participant in the Google Summer of Code™. This year we were fortunate and have ten students each of whom is attempting a project of interest to the RTEMS community. I encourage everyone to support these students in their work this summer...

March 16, 2012

The RTEMS Project has been accepted as a participating organization in the Google Summer of Code 2012. We have been busy in the off-season getting ready for potential students. Visit the updated...

February 14, 2012

embedded brains GmbH will once again be present at the Embedded world 2012 trade fair in Nuermberg, Germany, which is from February 28.-March 1. 2012. We will be present in Hall 5, Booth 5-311. The trade fair...

February 06, 2012

The RTEMS project has completed its switch to the GIT version control tool. I wish to thank Amar, Chris, and Jeff for completing this major change.

The git repositories are located on the '' server. There is support for the git protocol as well as access via the git web site...

December 13, 2011

The RTEMS Project is pleased to release 4.10.2. This is the third release from the 4.10 release series and includes both...

November 18, 2011

RTEMS now has a twitter feed -

. If you are into Twitter, then this is another way to get RTEMS...

November 10, 2011

The RTEMS Project is excited to be one of the 18 open source organizations participating in this year's Google Code-in contest for 13-17 year old students.

The RTEMS Project has put together a list of...