The systematic development of fault-tolerant real-time systems with guaranteed timeliness requires an appropriate system architecture and a rigorous design methodology. Those services of the architecture that help to simplify the work of the real-time programmer are described, taking the MARS architecture as an example. Programming in the large activities, i.e., the systematic derivation of task timing parameters from the requirements specification, are then addressed. Programming to meet a time budget is discussed, and the programming interface, the programming environment, and the testing and support tools are presented. The architecture and most of the tools have been implemented and can be demonstrated on a fault-tolerant prototype application.>

The authors propose a system architecture, MARS, which supports a strict separation of the issues of synchronization and timeliness, data transformation, and the dependability aspects (e.g., error detection, error handling, and redundancy management. The systematic development of fault-tolerant real-time systems with guaranteed timeliness requires an appropriate system architecture and a rigorous design methodology. The authors propose a system with strict separation of the issues of synchronization, dependability aspects, and data transformation. Dependability aspects are handled by the architecture. Synchronization and programming in the large are handled at the design level. The programmer only has to be concerned with a sequential program for which he has to meet a so-called time budget. The architecture and many tools have been implemented and can be demonstrated on a fault-tolerant prototype application.>

Event-triggered and time-triggered systems are compared with respect to their testability. To facilitate the comparison, three aspects of testability are introduced: test coverage, observability, and controllability. After a brief review of the problems of testing concurrent programs, the author compares the two system architectures with respect to each of these three aspects. The results of the comparisons favor time-triggered systems in all three aspects, most notably with respect to controllability and test coverage. Thus, time-triggered systems are inherently more testable than event-triggered systems. A series of experiments is summarized that shows that it is easy to achieve reproducible testing of time-triggered systems.>