A supermarket uses a Point of Sale (POS) terminal to keep track of the goods that it has in stock and to produce bills for customers. Whenever an item is sold the product code of the item is read into a till by a barcode scanner. Sometimes the barcode is not scanned properly. If this happens the product code must be rescanned or entered using a keyboard.

Once the product code has been entered the till looks up the price and name of the product in the supermarket's stock database. This information is printed on the customer's receipt. It also updates the product's record in the stock file to indicate that the product has been sold.

This system can be depicted by this system flowchart :

The system has to be a transaction processing system because a customer at a till would not be prepared to wait for a batch processing system to look up the price and name of the product. It is not worth spending a lot more money to purchase a real time system to carry out this task because small delays at peak times can be tolerated.

GCSE ICT Companion 04 - (C) P Meakin 2004