Smart Card Envelope

Hi Guys,
Here is a circuit that has been well tested with both pic,
and other standard compliant smart cards.

Since the card slot switch is open with a card in the slot,
the same pin could be used to for communication with another device.

The SOUND command in the main pic can make sound with the piezo,
and then switches to input to listen for serial comms from the keypad pic.

It is possible to fit an 80 bit cypher strength random hash table
encryption algo in the 16F628, while still maintaining hard/software
error checking, and command protocall.
Cheers, Art.