Supermarket : Computerised Till

After a customer has selected the items that he wants to purchase he takes them to a till to pay for them. Modern tills in supermarkets are actually small computers which are connected together on a local area network. They are known as Electronic Point of Sale (EPOS) terminals.

The network is used to connect the tills to the computer which stores the stock database.

The Payment Process

When an item is sold its product code is entered into the till (EPOS terminal). The product code is usually printed on the item as a number that a human can read and as a barcode which can be scanned using a barcode reader. The information included in the barcode for a product is country of origin, manufacturer and item code. Sometimes a barcode will not scan so the code must be typed on a small keyboard.

The entered product code is validated using a check digit that it contains to reduce the likelihood that the product code has been typed or scanned incorrectly.

The code is then looked up in the stock database on the store computer to find the product's price and name. If the product code has been successfully scanned and looked up then the till produces three outputs :

The products file in the stock database is updated to show that the item has been sold. The stock level for the product will be reduced.

When all of the items that a customer has chosen have been recorded by the till, the total price of the purchases is calculated and printed on the receipt.

Items Sold By Weight

Some items, such as fresh fruit and vegetables are sold for a certain price per kilogram. These items do not have barcodes printed on them. To find the price per kilogram of an item that is sold by weight the checkout operator must either :

The price per kilo is then looked up in the stock database. The items are weighed on a pair of electronic scales and the computer system automatically calculates the correct price for the item and prints it on the receipt.

Methods Of Paying

A customer can usually pay for his purchases with cash, by cheque or using a debit or credit card. If the customer chooses to pay with a debit or credit card then the till will establish a connection with the computer at the customer’s bank to make an EFTPOS transaction.

System Flowchart

Most supermarkets use a transaction processing system to record sales. This means that the products file in the stock database is updated very shortly after each sale takes place. The operation of the sales process is shown in this system flowchart :

A backup copy of each sale will be stored in a transaction log file so that the data can be recovered if the products file is corrupted.

Advantages Of Using Computerised Tills

The use of computerised tills instead of manual tills brings benefits for customers and the owners of a supermarket. Some of these are :

For Customer For Store
  • Receipts can include the names of the products that have been purchased as well as the prices.
  • The checkout operator can process sales more quickly as item prices are automatically looked up when a barcode is scanned. Therefore queing times are reduced.
  • The likelihood of an incorrect price being charged is reduced. This is because prices are looked up in a database instead of being read from price stickers on items and typed manually.
  • Processing customers' purchases at a till is speeded up. This means that each checkout operator can process more sales, reducing the cost of running the supermarket.
  • Because the tills are linked to a stock control system an accurate record of the stock levels can be kept. This will reduce the likelihood of the store selling out of an item and losing potential sales.
  • Each till can calculate how much money has been spent at it during the day. This can be used to check that no money is missing from the till at the end of each day.

GCSE ICT Companion 04 - (C) P Meakin 2004