There are many choices for RTOSes -- proprietary and open source. There is no one dominant RTOS because there are so many processor choices and so many different application requirements. Here are a few popular RTOSes (proprietary) * Integrity * Nucleus * RTXC Quadros * ThreadX * VxWorks Here are some of the open source RTOSes/OSes * eCOS * uClinux PSOS, vx works, PSOS, vx works,