6. Real time systems

Real time processing is usually found in systems which use computer control.

This processing method is used when it is essential that the input request is dealt with quickly enough so as to be able to control an output properly. For example, the computer inside the Engine Control Unit in a car has to manage the engine at every moment based on what the driver wants to do.

Real time processing has to be programmed very carefully to ensure that no input events are missed.

Note that real-time processing does not have to be 'fast'. For example, a traffic light system is a real-time system but it only needs to process data relatively slowly. On the other hand, controlling a car engine has to deal with input events happening every thousandth of a second so a very fast computer is needed to do this -but both the traffic-light and the car engine computers are carrying out 'real-time' processing.

Examples:

• Traffic lights
• Heart rate monitoring
• Aircraft control
• Computer games
• Controlling robots

NOTE: Some books will tell you that real time systems include ticket booking systems, flight booking, theatre seat booking systems etc. That is not correct - real time systems are time critical and instructions will take priority over anything else. Yes, booking systems need to be able to process data very quickly, but they are not as time critical as real-time instructions. However, exam questions will probably expect you to include booking systems within the category of real-time systems.