PURPOSE: To attain portability, diversion and exchange of stored information by combining a single or plural integrated circuit IC cards defined as the basic memory media.

CONSTITUTION: An IC card 25 that can be loaded and unloaded to/from a semiconductor disk device is used as an information memory means. The card 25 contains a memory circuit and a battery. A bus converting circuit 29 is set between an input/output bus 31 for disk input/output processing and a mother board bus 30. The circuit 29 applies the output signals sent from an address bus 32, a control bus 33 and an address setting circuit 36 to an input/output control circuit 37, reads out the selection signal of each card 25 and supplies the direction control signal to a bus control circuit 38 for control of writing. Furthermore the random access is possible to the card 25 since a data bus 34 is provided to the circuit 38.