2. Real time processing In real time processing, input is processed and acted upon immediately. Real time processing is used in mission critical applications where no delay in processing can be tolerated, such as automatic pilot systems, safety systems in cars and control systems in power stations. Real time processing is used in computer controlled systems where fast responses are needed e.g. controlling a robotic arm. However, real time processing does not necessarily have to be fast. For example, a traffic light system has to deal with many inputs such as the number of cars building up at its junctions and it has deal with these inputs within a few seconds. A few seconds is a vast amount of time for a typical microcontroller / computer as it can process millions of inputs per second if need be. The point is that the system must produce an output within a guaranteed time.

3. Real time transaction processing Real time transaction processing is similar to batch processing except that the whole input process output cycle is completed for each transaction before the next transaction is processed. It differs slightly from pure real time processing in that a delay of up to a few seconds is usually acceptable between the transaction taking place and the files being updated. Single transaction inputSingle transaction processed Output relating to single transaction In real time transaction processing, the processing is immediate because it is vital that data files are updated to reflect the current situation so that they can influence future transactions. As a result, the records held are kept accurate and up to date and can queried at any time to retrieve accurate information.

4. Library systems, where books borrowed are immediately recorded as being unavailable and on-loan to a particular person Retail systems, where users build up a ‘basket’ and then go to the ‘checkout’ option where the availability is confirmed in real time. Online booking systems, where the user will book several things at once (for example, flights, hotel, car etc) ATM machines where a withdrawal of cash is recorded immediately and the customers balance is immediately updated to reflect the withdrawal. Examples where these applications are useful: