- C1 - VCC : Power supply
- C2 - RST : Reset signal, used to reset the card's communications.
- C3 - CLK : Provides the card with a clock signal, from which data communications timing is derived.
- C4 : AUX1. Used for USB interfaces and other uses.
- C5 - GND : Ground (reference voltage)
- C6 - VPP : ISO/IEC 7816-3:1997 designated this as a programming voltage: an input for a higher voltage to program persistent memory (e.g., EEPROM). ISO/IEC 7816-3:2006 designates it SPU, for either standard or proprietary use, as input and/or output.
- C7 - I/O : Serial input and output (half-duplex).
- C8 : AUX2. Used for USB interfaces and other uses.