IC CARD

摘要

PURPOSE:To easily set a first certification data and simultaneously to keep the secrecy of the internal data by supplying just once the certification data directly to a RAM right after the production. CONSTITUTION:A terminal 8 is short-circuited after each element and terminal are mounted at a production stage. Thus a CPU 11 performs an interruption process and clears all memory areas of a RAM 15. Then the terminal 8 is covered by molding from outside and shipped. Therefore the terminal 8 is never short-circuited again and the RAM 15 is never cleared. The certification numbers can be freely written just at the first time when the RAM 15 is cleared. hereafter the certification number cannot be changed into a novel number before the number already written is supplied. As a result, only a permitted user can give an access to the internal data and therefore the secrecy of the internal data is secured.