An IC has pads provided on the conductors that are connected to the input/output
terminals of a memory block thereof so as to allow the input/output pads of an
external memory chip to be connected to the pads of the IC. By superposing the
memory chip on the IC with their pads mutually connected, expansion of memory is
achieved without increasing the chip size. The IC has a control circuit for determining
whether to use the memory block or the memory chip so as to allow switching between
them as required.
