Signposts and Landmarks : Reliability and Safety of Real - Time Systems

A pplications that call for real-time systems are particularly susceptible to failures. Our challenge is to design, analyze, and build such systems to prevent failures or (at least) to mitigate their effect on operations. The theme articles in this issue, summarized in the box on p. 14, explore different ways to meet this challenge. What differentiates the development of real-time systems software from other applications? How do reliability and safety figure into their development? A real-time system must respond to externally generated stimuli within a finite, specifiable time delay. Real-time systems are typically embedded systems that interface directly to the physical equipment they operate, monitor, and control. Examples of such systems are flightand weapons-control systems, air-traffic-control systems, telecommunications-switching and -network equipment, manufacturing process-control, and even speech-recognition