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.

RTEMS News

January 23, 2009

(January 23, 2009) The year was 1993 and the U.S. Army was trying to promote the benefits of RTEMS. As part of that, a brochure was created. Where you lucky enough to have gotten one of these? If not, we have...

December 12, 2008

(December 12, 2008) The RTEMS Project is pleased to release 4.9.1. This is the second release from the 4.9 release series and is...

September 23, 2008

(September 24, 2008) The RTEMS Project is pleased to release 4.9.0. This is the first release from the 4.9 release series and is a new...

September 09, 2008

(September 10, 2008) The RTEMS Project is pleased to announce that the CVS Branch for the 4.9 Release Series has been cut. We have entered a (hopefully short) period testing and polishing which will culminate with the 4.9.0 release. A side-effect of cutting the 4.9 Branch is that the CVS head...

August 12, 2008

(August 13, 2008) The RTEMS Project is pleased to release 4.8.1. This is the second release from the 4.8 release series and...

August 07, 2008

(August 8, 2008) On this numerically interesting date, 4.7.3 is released to the RTEMS Community. This is the fourth release from the...

April 20, 2008

(April 21, 2008) RTEMS was fortunate enough to be included as Google Summer of Code project and received four student slots funded by Google. There were over three times as many student proposals as funded slots and all were good. In addition to the four funded student proposals, a few other...

February 14, 2008

(February 14, 2008): Happy Saint Valentine's Day!!! Today there were two RTEMS releases. The first of these is the long anticipated 4.8.0....

February 14, 2008

(February 14, 2008): The second Valentine's Day present to the RTEMS Community is the 4.7.2 release. This is the third release from the...