The Operating System Embedded (mostly known under the acronym OSE), a real-time embedded operating system created by the Swedish firm ENEA.
OSE uses signaling in the form of messages passed to and from processes in the system. Messages are stored in a queue attached to each process.
The system exists in several revisions named OSE Delta, OSE Epsilon etc. Most companies developing software with OSE use compilers from IAR Systems and ARM processors.