The principle of operation of telephone cards

There are two main types of chip phone cards is a 8 pin and 6 pin normally in a 6-pin cards are 5 contacts, among 8 contact cards are also instances that use only 5 contacts, the other to the load.

Cards contain electrically programmable ROM 256 * 1 bit bit at a consistent delivery of information and incremental internal address counter. The write operation produces a change in the state of memory cells of "one way" to change it back (erase) the card interface is not provided.

The connection of the card to the computer for reading and writing is mainly carried out via LPT port. Unfortunately the card can not be overwritten because after the first record fusible fuse. To collect the emulator phone cards.

The procedure performed kartofonom when you call

Turn on the power.

The reset.

Read the first 8 bytes and determining whether the card is valid in this region, keeping them in RAM (if necessary decoding).

Reading five byte units and stored in the RAM. Verification of compliance units available capacity of the card, encoded in the first 8 bytes.

The power is turned off.

After receiving the signal response of the called subscriber

Turn on the power.

The calculation of the address of the last written off bits. (approximately 1-3 seconds after pressing the "answer")

The reset.

Filing number of pulses. CLK corresponding to the address of the last written off bits.

The command to WRITE.

The command WC.

Read the first 8 bytes and determining whether the card is valid in this region, keeping them in RAM (if necessary decoding).

Reading five byte units and stored in the RAM. Verification of compliance units available capacity of the card, encoded in the first 8 bytes, check whether the unit decreased compared to the previous reading.

The power is turned off.

After a minute, if the connection is not broken, then the action from the first to the ninth repeated cyclically.

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