Predictable hard real-time scheduling

The essential feature of hard real-time systems is that the embedded computer must deliver its results correctly and on-time - otherwise malfunction may result. To assure software constructions of such systems a support of a real-time operating system is needed. We present a task scheduling and mutual exclusion protocol as one of real-tame operating system structuring mechanisms. The protocol is applicable to aperiodic tasks having specific priority and timing characteristics.