Abstract: A card reader/writer which interfaces between a host application program and a data storage card. The card reader/writer reads from and writes to the application program with high level language of the commands. The card reader/writer translates the high level language commands of the host program to corresponding sequences of low level commands for reading and writing to the data storage card. The card reader/writer stores a plarality of sets of such low level commands, and is able to establish the card type for any card interfaced with the card reader/writer, and to use the appropriate command set for the established card type. The card reader/writer also translates low level commands from the card to high level commands for the host application program. The card reader/writer can be loaded with low level command sets for additional card types as required.