Magnetic Strips

This is another method of storing computer data on an object (normally a card). Magnetic strips are use on credit and debit cards and also on ‘smart cards’ such as photocopying cards, loyalty cards where you collect points etc.

A magnetic strip is a short length of magnetic coating printed on to the surface of a ticket or card. The stripe usually contains data to identify the ticket or the card or its user eg. an account number and an expiry date.

To swipe a card with a magnetic strip means to move the card through a reader so that the stripe can be read.

Some examples of how a magnetic strip is used:

· Tags attached to clothes in a shop.

· Railway, bus and underground tickets.

· Credit cards and bank cards.

· Phone cards.

Advantages

· Easy to make.

· Not easy to damage.

· Stores quite a lot of data (up to 72 characters).

· Cut down the amount of writing done during a transaction.

Disadvantages

· The data can be changed or erased by magnetic fields.

· The stripe can be damaged by scratching.

Other Uses

Smart cards are very similar but the data in the magnetic strip can be changed easily by altering the contents of a very thin memory chip. They are used for photocopying cards and some loyalty cards where you collect points.

Applications

Credit cards – A shop or business will have a terminal where the card is checked and payment is authorised. The terminal is linked to the shop’s own bank. The bank then calls up the credit card company’s own computer. This computer checks that the card is valid and has not been lost or stolen. A message is then sent back to the shop which then goes ahead with the sale.

ATM (automatic telling machine) – Many people use a card to get money out of the bank when they are closed. They go to an ATM which gives them money after you have put in the card and entered in a PIN (personal identification number).