Address mapping logic for transferring data between a peripheral device of a base function expander unit and a palmtop computer as if the peripheral was a peripheral of the computer

A method for providing an information storage and transfer device for use with a palmtop computer having an IC memory card drive for reading and writing IC memory cards of a proprietary format, an internal address bus and a data bus, said method comprising the steps of:

• providing a local address bus including a first plurality of address signals and a second plurality of address signals;
• providing an interface for coupling said second plurality of address signals of said local address bus to said internal address bus and said data bus of said palmtop computer, so as to allow data transfer between said palmtop computer and said information storage and transfer device;
• providing an input and output port for connection to external devices;
• providing a peripheral device;
• and
• providing an address mapping logic circuit, coupled to said interface and said local address bus, for driving said first plurality of address signals in said local address bus, said address mapping circuit mapping said peripheral device and said input and output port each to an address of said palmtop computer, so as to allow data transfer between said palmtop computer and said peripheral device and said input and output port to occur over said interface as if said peripheral device and said input and output port are a peripheral device and an input and output port of said palmtop computer.