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 block and a non-rewritable one, and the phone writes only 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 lot of complexity of implementation, but it is redeemed by the fact that on the basis of 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 implemented 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 a high-grade 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.
We read the information (firmware) from the new card with the help of the program using this program and you can write down information on an empty card if it is not a one-time card
We'll 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 is ready for use.