Card reader/writer devices and methods for reading/writing both M-cards, PICCs, and/or S-cards, wherein such devices can comprise a magnetic head (which can have multiple tracks), an A/D converter, a gated buffer module associated with the A/D converter, an F2F decoder associated with the gated buffer module for enabling the integration of multiple discrete M-card reader formats with decoder functions, and an integral PICC data processor, which can perform the functions of a PCD, for reading/writing a PICC along with the M-card. An internal RF analog antenna circuit can be provided for receiving signals from the PICC, or an external PCD antenna can be connectable to the RF circuit. The F2F decoder can be integrated with the PICC data processor, and the A/D converter can process analog data from both the magnetic head and the RF antenna circuit. A contact module could also be provided to read/write an S-card.