Introduction

The built-in notion of time and how it is used in the system is the basic difference between real-time systems and non-real-time systems. More formally, a real-time system is defined as one in which the correctness of its output(s) depends not only upon the logical computations carried out but also upon the time at which the results are delivered to the external interface. In other words, a real-time computation is considered wrong (not just late!) if the results are generated at the wrong time.