Real Time System

Real Time System

• Time constraints is the key parameter is real time systems. It controls autonomous system such as robots, satellites, air traffic control and hydroelectric dams.

• When user gives an input to the system, it must process within the time limit and result is sent back. Real time system fails if it does not give result within the time limits.

• Real time systems are of two types: Hard real time and soft real time.

• Critical task is completed within the time limit in hard real time system. All the delay in the system is fixed and time bounded. Existing general purpose operating system does not support the hard real time system functions. Real time task cannot keep waiting for longer time without allocating kernel.

• Soft real time system is less restrictive type. Soft real time cannot guarantee that it will be able to meet deadline under all condition. Example of soft real time system is digital telephone and digital audio.

• Real time operating system uses priority scheduling algorithm to meet the response requirement of a real time application. General real time applications with their example are listed below:

1. Transportation: Air traffic control and traffic light system

2. Communication: Digital telephone

3. Process control: Petroleum and paper mill

4. Detection: Burglar system and radar system

5. Flight simulation: Auto pilot shuttle mission simulator.