Note To Reviewers.

Reproducible and deterministic testing of sequential programs can in most cases be achieved by controlling the sequence of inputs to the program. The behavior of a distributed real-time system, on the other hand, not only depends on the inputs but also on the order and timing of the concurrent tasks that execute and communicate with each other and the environment. Hence, sequential test techniques are not directly applicable, since they disregard the significance of order and timing. In this paper we present a method for identifying all the possible orderings of task starts, preemptions and completions for tasks executing in distributed real-time systems. Together with an accompanying testing strategy this method allows test methods for sequential programs to be used, since each identified ordering can be regarded as a sequential program. In the presented analysis, and testing strategy, we take into account the effects of interrupts, clock synchronization, and varying start and execution times of the involved tasks.