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Emulator of payphone card

The basis for constructing emulators of different cards is the following principle. Since the memory of the smart card consists of a rewritable unit and a non-rewritable one, and the phone only writes to the rewritable area, what prevents us from reading the information from the new card and saving it somewhere? Let the algorithm of the phone depends on the contents of the "non-rewritten" area of ​​memory, and it is individual for each card instance, but this area is unchanged! The only drawback of this method can be considered quite a laborious implementation, but it is redeemed by the fact that based on this principle, emulators are implemented almost all cards, including even SIM-cards of cell phones.

The implementation of the emulator on this principle can be carried out in two ways. The first is that a logical circuit is assembled that implements the entire logic of the "device-card" scheme. However, the scheme turns out to be rather cumbersome. The second method, which is described below, is based on the use of microcontrollers. Basically, they suggest using microcontrollers from the PIC-series, but to program such a controller is the highest degree of humor. And somehow everyone forgets about the availability in stock   Controllers of other series, including ours, domestic. But I do not recommend the latter because of their great and mighty size. The most acceptable in my opinion is the use of the Motorola MC68NS705K1 motor controller. Firstly, it is quite easy to find, secondly, it is cheap. So, everything is very simple. We collect the programmer according to the scheme shown in the figure.

The programmer.

The scheme of the programmer

We read the information (firmware) from the new card using the program with the help of this program it is possible to write down information on an empty card if it is not a one-time card

We will program the controller by connecting it to this LPT port of the computer using the program. Download 32 kb

We collect the emulator according to the scheme.

The emulator.

The scheme of the emulator of a telephone card

The emulator is ready for use.