<p>A memory cartridge having a dynamic memory unit, which is provided with an access conversion circuit for converting a static access signal into an inverted signal and an access control circuit which switches a signal that refreshes the dynamic memory unit and a signal that makes access from the external side to each other. The memory cartridge is further equipped with a power source switching circuit that switches the internal power source to the external power source when the cartridge is mounted on an external device.</p>
