Coin-shaped integrated circuit memory device

An integrated circuit memory device without a battery adapted to be stored in an electronic device having a control section and a battery and which is capable of attachment to a wrist of a user, comprising:

• a circuit substrate with two surfaces and having a data terminal, power terminals for a power source and a data-writing terminal for writing data, such terminals being formed on one of said two surfaces, connecting terminals formed on the other of said two surfaces, and through holes formed, respectively, between said data terminal, power terminals and data-writing terminal and said connecting terminals, said connecting terminals being, respectively, connected with said data terminal, said power terminals and said data-writing terminal through one of said through holes;
• a non-volatile integrated circuit memory chip having electrodes connected with said data terminal, power terminals and data-writing terminal, respectively, and being selectively changeable in a data-writing state and in a data-reading state in accordance with a data-writing signal and a data-reading signal respectively supplied to said data-writing terminal of said circuit substrate, said non-volatile integrated circuit memory chip being mounted on said circuit substrate;
• a case including a core member and a cover bonded to one surface of said core member, said cover being formed by a thin metal plate, said core member having a ring shape for storing therein said non-volatile integrated circuit memory chip and a perimeter having substantially a circular outer surface which includes a notch depressed from said circular outer surface, said circuit substrate being bonded to said core member at another surface side of said core member;
• and
• a changeover switch having a knob positioned in said notch of said core member for selectively setting one of a data-writing allowable state and a data-writing preventive state.