A hardware supported operating system kernel for embedded hard real-time applications

In this paper a concept of the kernel, i.e., the time critical part of a real time operating system and its dedicated co-processor, especially tailored for embedded applications, are presented. The co-processor acts as a system controller and operates in conjunction with one or more conventional processors in hard real time environments. It is composed of three physically and clearly separated layers which vary with regard to implementation, speed, and complexity. Correspondingly, the model of the operating system kernel is hierarchically structured, and functions are mapped to these layers, observing the inherent parallelism of recognition and handling of diierent kinds of events expected in such environments and higher level kernel functions like tasking operations. The operating system functions are supported by the high level real time programming language constructs. Since many embedded systems are safety related, the software employed must be highly dependable. Therefore, the kernel was proven correct with formal methods, which represents a major innovation in software technology.