ABSTRACT
Real-time systems are those in which the correctness of the system depends not only on its functional correctness but also on the time at which the results are produced. For example, if the MPEG decoder inside your DVD player is not capable of decoding frames at a specified rate (say 25 or 30 frames per second) then you will experience video glitches. Thus although the MPEG decoder is functionally correct because it is able to decode the input video stream, it is not able to produce the result at the required time. Depending on how critical the timing requirement is, a real-time system can be classified either as a hard real-time or a soft real-time system.
