Software dependability considered as the main problem of embedded systems

Numerous real time and embedded control systems are safety related. Hence, the software involved must be rigorously verified, i.e., safety licensed, since it is far from being as dependable as hardware. Licensing, however, is very critical and difficult, and satisfactory methods are still missing. Therefore, the intrinsic problems and fundamental principles of safety licensing software are worked out. The importance of the human element in this process, as well as the need to strive for utmost simplicity in order to effectively cope with complexity, and to look for subject oriented approaches are emphasised. As examples of software development paradigms especially suitable for safety critical control systems and trustworthy verification cause effect tables and function block diagrams are mentioned.