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Payphone Card Emulator

The basis of the construction of emulators of various cards is the following principle. Since the smart card memory consists of a rewritable block and a non-rewritable block, and the telephone set writes only to a rewritable area, what prevents us from reading information from a new card and saving it somewhere? Let the telephone operation algorithm depend on the contents of the “non-rewritable” memory area, and each card instance is individual, but this area is unchanged! The only drawback of this method is the rather high complexity of the implementation, but this is redeemed by the fact that, based on this principle, emulators of almost all cards, including even SIM cards of cell phones, are implemented.

The implementation of the emulator on this principle can be done in two ways. The first is that a logical circuit is going to be implemented that implements all the logic of the "device-card" circuit. However, the scheme is rather cumbersome. The second method, which is described below, is based on the use of microcontrollers. Basically, they propose using microcontrollers from the PIC-series, however, programming such a controller is the highest degree of gimor. 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 powerful size. The most acceptable in my opinion is the use of the Motorola controller MC68NS705K1. Firstly, it is quite 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 a program using this program, you can write information to a blank card if it is not one-time

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

We collect the emulator according to the scheme.

Emulator

Calling Card Emulator Scheme

The emulator is ready to go.