This paper maintains that fixed-priority process-based preemptive scheduling is, arguably, more convenient, flexible and responsive than conventional cyclic scheduling for the construction of new-generation software-intensive satellite control systems. Predictable usage of preemptive priority-based scheduling, however, demands the support of mature static analysis techniques. Worst-case response time analysis models can be constructed which minimise the embodied pessimism and maximise useful

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... cessing. This paper presents the design and implementation of an Ada programming model and associated worst-case response time analysis tools aimed to support the construction of highly-predictable, highly-efficient on-board control systems.