Background Correctness of the system depends not only on the logical result of the computation but also on the time at which the results are produced (系统的正确性不仅取决于计算的逻辑结果,而且还 依赖于产生结果的时间) Tasks or processes attempt to control or react to events that take place in the outside world (实时任务或进程试图控制外部世界发生的事件或对 这些事件作出的反应) These events occur in“‘ real time” and process must be able to keep up with them (这些事件是“实时”发生的,进程必须能够跟随处 理这些事件)Background • Correctness of the system depends not only on the logical result of the computation but also on the time at which the results are produced （系统的正确性不仅取决于计算的逻辑结果，而且还 依赖于产生结果的时间） • Tasks or processes attempt to control or react to events that take place in the outside world （实时任务或进程试图控制外部世界发生的事件或对 这些事件作出的反应） • These events occur in “real time” and process must be able to keep up with them （这些事件是“实时”发生的，进程必须能够跟随处 理这些事件）