If a job must never misses its deadline then the system is called hard real-time system. For a hard real-time system, every deadline must be hit. In a real hard real-time system, if the system fails to hit the deadline even once the system is said to have failed.

A hard real-time system is also known as an immediate real-time system. It is a hardware or software that must operate within the confines of a stringent deadline. The application is considered to have failed if it does not complete its function within the given allocated time span. Some examples of hard real-time systems are medical application like pacemakers, aircraft control systems and anti-lock brakes. Some characteristics of hard real time system are:

  • The hard real-time system is called guaranteed
  • Response time is hard
  • Often safety critical
  • Size of data files are small and medium
  • Peak load performance is predictable
  • Use the autonomous error detection
  • Have short-term data integrity