ChorusOS is a microkernel real-time operating system designed as a message passing computing model. ChorusOS began as the Chorus distributed real-time operating system research project at the French Institute for Research in Computer Science and Automation (INRIA) in 1979. During the 1980s, Chorus was one of two earliest microkernels and was developed commercially by startup company Chorus Systèmes SA. Over time, development effort shifted away from distribution aspects to real-time for embedded systems.