There is a strip of magnetic tape on the back of your credit card, often called a magnetic strip. Magnetic strips consist of tiny iron-based magnetic particles arranged on a plastic-like adhesive film. Each particle is actually an extremely tiny magnetic strip, with a length of approximately one eight hundredth of a micron.
Magnetic strips can "write" data because these tiny magnetic strips can be magnetized into north and south magnetic poles. The magnetic strip on the back of a credit card is like an audio cassette tape attached to the back of a credit card. When a credit card is swiped or inserted into a gas station card reader, the power is provided by your hand, rather than a motor driving the data like a tape. There are three tracks on the magnetic stripe, each track is 2.79 mm wide.
Track 1: The stone recording density is 210 bits per inch (bpi), which can record 79 read-only characters. The length of each character is six bits plus a parity check code.
Track 2: The recording density is 75 bits and can record 40 characters. The length of each character is four bits plus a parity check code.
Track three: The recording density is 210 bits, and 107 characters can be recorded. The length of each character is four bits plus a parity check code.
The first track contains information in two formats: Format A, which is used exclusively by the card issuer, and Format B, which includes the following:
Start tag—— 1 character
Format code="B" - 1 character (alpha only)
Junior account - up to 19 characters
Delimiter ——1 character
Country (/region) code——3 characters
Name——2 to 26 characters
Separator——1 characters
Expiration date or separator - 4 characters or 1 character
Depending on the data - enough characters to fill the longest record (***79 characters )
End marker - 1 character
Longitudinal redundancy check code (LRC), a calculated check character - 1 character
< p>The second track contains the following content and format:Start tag - 1 character
Junior account number - up to 19 characters
Separated Character - 1 character
Country (/region) code - 3 characters
Expiration date or delimiter - 4 characters or 1 character
Discretionary data - enough characters to fill in the longest record (***40 characters)
Vertical redundancy check code - 1 character
Track three It is read-write and can store encrypted personal identification numbers, country or region codes, currency units and credit limits, but the purpose of this track is not standardized among banks. Credit cards usually only use track one and track two.
Supplement
There are three ways to confirm that the credit card charges for you:
Merchants with few transactions per month can use touch-tone audio phones to make voice calls. Identify.
Electronic Data Capture (EDC) magnetic card terminals are becoming increasingly common – and so are card checkouts.
Virtual terminal on the Internet. The way it works is:
You or the cashier swipe your credit card through the card reader, and the electronic data collection software at the point of sale terminal (POS machine) dials the stored phone number through the modem to call the acquiring bank. The acquiring bank collects credit verification requests from merchants and provides payment guarantees to merchants. When the acquiring bank receives a credit card verification request, it reviews the transaction for verification and checks the following records on the magnetic strip: merchant number, valid card number, expiration date, credit card limit, and card purpose.
Dial-up transactions are processed at only 1200 to 2400 bits per second (bps), while a direct Internet connection through this protocol is much faster. In this system, cardholders use a keypad to enter a personal identification number (PIN).
If the ATM does not recognize your credit card, there may be one of the following problems:
The credit card is dirty or has a scratched magnetic strip.
Magnetic strip degaussing. The most common cause of degaussing is exposure of the magnetic strip to magnets, such as the small magnets used to attach notes and pictures to refrigerators, and the degaussing of Electronic Article Surveillance System (EAS) tags. device.
Methods to protect the magnetic stripe of a bank card:
It is best to keep the bank card in a hard-covered wallet, not too close to the magnetic clasp. Never throw it away in a messy bag to prevent sharp objects from wearing out, scratching the magnetic strip, or twisting and breaking it.
It is best not to store multiple bank cards close together, let alone place two bank cards back to back so that the magnetic strips rub or collide with each other.
Stay away from high magnetic fields around induction cookers, microwave ovens, TVs, refrigerators and other electrical appliances as much as possible, and try not to put them together with magnetic items such as mobile phones, computers, PDAs, magnets, Wenquxing, and Business Express. .