IT in the Supermarket

Information systems are used widely in shops and in the distribution of goods and one area in which their use is particularly important is supermarkets.  Computer systems are used in a variety of ways in the modern, large supermarket, from stock control to maintaining temperatures in fridges and freezers.  In this section we will look in more detail at these systems in one particular large supermarket, which is part of a national chain.

The supermarket uses several computers which are located in a room known as the system office and form the supermarkets own Local Area Network.  These computers are used to control the stock and are connected to the checkouts.  These are  the 'branch computers'.   The computers are multi-functional, and each can access the data, which gives the management a number of access points.

Admin and stock control staff now have access to hand held computers, SEC (Shelf Edge Computers).  These are used for price changes, creating stock pictures (information on stock totals) and for forecasting deliveries.

Like many companies, they have experimented with giving customers hand held scanners to enter their own shopping.  The experiment has been discontinued due to huge stock losses, staff called them ‘Shop and Rob’ rather than ‘Shop and Go’.  The company is currently looking at developing a better system to get round these problems.

Located at each checkout is an ELECTRONIC POINT OF SALE ( EPOS ) till.  This

EPOS till comprises a keyboard, a digital display, a scanner which reads bar codes, a set of scales, a printer, a credit / debit card reader and a till drawer.  Each till also has its own base to which all of the above is attached.  It is the base unit which is connected by cables to the branch computer in the supermarket's system office.

Each product to be sold must have an identifying code number which is different from that of every other product.  Different sizes of the same product even need different code numbers.  These code numbers are printed onto the labels or packaging of the product in the form of bar codes.

Bar codes are made up of a set of black lines and white spaces.

 

Look at the bar code.  You can see that it is split into two halves, and each half is contained within two thin black stripes.

The diagram shows the pattern of lines for each digit on the bar code.  Notice that the pattern for a digit on the right hand half of a bar code is the opposite of the one on the left hand half.

Many bar codes today use the European Article Number or EAN.  This is a thirteen

digit number which can be used to uniquely identify a product.  Using the bar code shown as an example :

 

a) The first 2 digits represent the country from which the company producing the

product comes.  50  - U.K.

b) The next five digits represent the company which produced the product.  00208 - Lyons Tetley Ltd.

c) The following five digits represent the product. 02100 - 80 Tea bags.

d) The last number is a check digit. This is used to make sure the bar code has been read correctly.

So 5000208021000 is the EAN for a box of 80 Tetley tea bags.

 

The bar codes on products are read by the EPOS tills at the checkouts.  This is

achieved by using a scanner, which sends out infra-red laser beams via a set of mirrors, enabling the bar code to be read at most angles.

When an item is passed over the scanner, the black and white parts of the code are detected by the laser, as the black parts reflect very little light whilst the white parts reflect most of the light. This is converted into electrical pulses which are sent along the cables to the branch computer.  The branch computer then searches its stock file for the product matching the EAN number.  When this record is located the price and description of the product is extracted and sent back to the EPOS till at the checkout which then shows this item and price on the digital display, prints them on a receipt and adds the price to the total.  At the same time, the branch computer records that one

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of this item has been sold.  We will look at how this is used for stock control on other pages.  

When a bar code has been correctly scanned, the scanner emits a bleep.  If no such sound is made, the item can be passed over the scanner again until it has been correctly read.  The keyboard is used to enter codes of products that will not scan, for example reduced price items.  

The scales at the EPOS till are also linked up to the branch computer.

All loose fruit and ...

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