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Payphone card emulator

At the heart of building emulators of various cards is the following principle. Since the memory of a smart card consists of a rewritable block and a non-rewritable one, and the telephone apparatus writes only to the rewritable region, 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-rewritable" memory area, and it is individual for each copy of the card, but this area is unchanged! The only drawback of this method can be considered as a rather large laboriousness of implementation, but this is redeemed by the fact that based on this principle, emulators of almost all cards are implemented, including even SIM-cards of cellular phones.

The implementation of the emulator on this principle can be done in two ways. The first is that a logical circuit is assembled that implements the entire logic of the "apparatus-card" circuit. However, the scheme is quite cumbersome. The second method, which is described below, is based on the use of microcontrollers. In general, they propose to use microcontrollers from the PIC-series, however, to program such a controller is the highest degree. And for some reason everyone forgets about the estate available   controllers of other series, including ours, domestic. But I do not recommend using the latter because of their great and mighty size. The most acceptable in my opinion is the use of the MC68HC705K1 motorola controller. First, it is fairly easy to find, and secondly, it is cheap. So, everything is very simple. We assemble the programmer according to the scheme shown in the figure.

Programmer.

Programmer circuit

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

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

We assemble the emulator according to the scheme.

Emulator

Calling card emulator circuit

The emulator is ready to go.