The stripe on the back of a credit card is a magnetic stripe , often called a magstripe . The magstripe is made up of tiny iron-based magnetic particles in a plastic-like film. Each particle is really a very tiny bar magnet about 20 millionths of an inch long.
The magstripe can be "written" because the tiny bar magnets can be magnetized in either a north or south pole direction. The magstripe on the back of the card is very similar to a piece of cassette tape fastened to the back of a card. Instead of motors moving the tape so it can be read, your hand provides the motion as you "swipe" a credit card through a reader or insert it in a reader at the gas station pump. There are three tracks on the magstripe. Each track is .110-inch wide. The ISO/IEC standard 7811, which is used by banks, specifies:
Your credit card typically uses only tracks one and two. Track three is a read/write track (that includes an encrypted PIN, country code, currency units, amount authorized), but its usage is not standardized among banks. The information on track one is contained in two formats -- A, which is reserved for proprietary use of the card issuer, and B, which includes the following:
The format for track two , developed by the banking industry, is as follows:
There are three basic methods for determining that your credit card will pay for what you're charging:
This is how it works: After you or the cashier swipes your credit card through a reader, the EDC software at the point of sale (POS) terminal dials a stored telephone number via a modem to call an acquirer . An acquirer is an organization that collects credit authentication requests from merchants and provides a payment guarantee to the merchant. When the acquirer company gets the credit card authentication request, it checks the transaction for validity and the record on the magstripe for:
Single dial-up transactions are processed at 1200-2400 bps, while direct Internet attachment uses much higher speeds via this protocol . In this system, the cardholder enters a personal identification number (PIN) , using a keypad . If the ATM isn't accepting your card, your problem is probably either:
Here are some interesting links: |