magnetic stripe card
In the past, there were magnetic stripe cards or magnetic cards whose magnetic stripe has been replaced by a chip over the years. Classic magnetic cards are plastic cards with magnetic stripes. The size is standardized by ISO and corresponds to the ID1 format with dimensions of 85.6 mm x 53.6 mm and a thickness of 0.76 mm.
On the back of the magnetic card there was a magnetic stripe extending over the entire width of the card with three magnetic tracks recorded on it. The position of the magnetic stripe was specified under the ISO standard ISO 7816, which specifies the dimensions, electromagnetic radiation, mechanical stresses, position of the magnetic stripe and electrostatic stresses.
The magnetic stripe was used to record and store user data. It was divided into three tracks, which had different recording densities and on which the data, together with the clock signal was modulated by means of Pulse Width Modulation( PWM) or Modified Frequency Modulation( MFM), Frequency to Double Frequency( F2F). Tracks 1 and 2 could only be read, while track 3 could also be written. The first track was used for alphanumeric data such as name and address, the second track was for numeric data and was used for identification data, and the third track could be written with numeric data from recent transactions.
Track 1 could store 79 alphanumeric characters. The storage was done with 6 data bits and one parity bit in a track density of 210 bpi( bits per inch). On track 2, 40 digits could be stored. Storage was with 4 bits and one parity bit at a track density of 75 bpi. And track 3 offered space for 107 digits, also stored with 4 bits and one parity bit. The track density was 210 bpi.
Magnetic cards were used for access identification and authorization of persons, as cash cards in banking, as inexpensive settlement cards for parking fees, hotel keys, admission tickets and in various other applications.