Gold wafer cards
The Gold smart card incorporates just two ICs: a PIC16F84(A) and a 24(L)C16 EEPROM.
The diagram depicts the internal interconnections. As you can see, the EEPROM is not wired to the interface contacts but is controlled exclusively by the PIC.
In a real application, the PIC is programmed with a card operating system. The function of this operating system depends entirely on the card's application but at least one of its tasks is to provide access to EEPROM data via the interface.
With this arrangement, the requirements for EEPROM access are quite straightforward. They entail a relatively simple hardware interface to the card and some software that can speak the ISO protocol. This was the basis of the first reader/programmer design.
How it works
As outlined earlier, the cards that we wish to read and write contain two separate ICs: a PIC microcontroller and an EEPROM. To access the EEPROM, a Smartmouse or Phoenix-type interface is required. On the other hand, to read or program the PIC's internal memories, a PIC programming interface is required.
The design solves this conundrum by providing both types of interfaces. A 4-pole 2-position pushbutton switch (S1) is used to select between the two interfaces, or "modes". The fig shows the circuit details for the Smart Card Reader/Programmer.