This invention provides an image processing system which is built by
connecting a host device which reads out and executes program data stored
in a storage medium, and a device added with a card device function, and
which allows easy device connection and has high convenience. In this
system, the device connected to the system has a communication controller
(11) for controlling a communication between the host device and the
device, a card interface (31) for connecting a card device, a card
controller (30, 40) for controlling a card device which is detachably
connectable to the card interface, a communication unit (2, 3) for
sharing device information between the host device and the card device
via the card controller and the communication controller, and a
controller (10) for allowing another device connected via the card device
to use information shared by the communication unit.