Real time system: A real time system is the one in which computations should be completed in a specific time frame. In real time systems delays cannot be allowed. These systems are used in hospitals, airlines, etc. where fault tolerance is undesirable. Real time systems can be classified as:
Hard real time system: A hard real time system is the one where deadlines should be met at all costs.
Soft real time system: A soft real time system is the one where some delays can be tolerated.
Schedulable real time system: Real time systems are considered schedulable if they meet the equation:
Here, Pi is the time period and Ci is the CPU time to manage each event, i is the event and m is the number of events.