Abstract: YARTOS is an experimental real-time operating system kernel that provides guaranteed response times to tasks. It is currently used as a vehicle for research in the design, analysis, and implementation of real-time applications. It is a micro-kernel with an underlying formal model based on sporadic tasks with response time requirements and shared software resources. It is distinguished by the programming model it supports and by its use of a novel processor scheduling and resource allocation policy. The implementation of YARTOS is outlined and two real-time applications that run under YARTOS are described.