I think you are referring to a “Season 7” interface by which a PC could emulate a smart card for pay TV encryption. One side was a PCB the shape of a SmartCard

I think you are referring to a “Season 7” interface by which a PC could emulate a smart card for pay TV encryption. One side was a PCB the shape of a SmartCard, only slightly longer. The part protruding from the satellite receiver/TV decoder had a single 74hc driver on it (I think an open collector driver of some sorts to handle the half duplex, bidirectional, data pin of the smartcard interface).