| 摘要 |
PURPOSE:To prevent the software of a memory card from being copied by providing a data process circuit which takes the exclusive 'OR' of each output of a ROM and RAM and outputs processing data for discriminating the data previously written in the ROM. CONSTITUTION:Software protecting data, etc., are previously written in the ROM 84. The RAM 83 is actuated by means of the same chip selecting signal as that used for actuating the ROM 84 and data from the user of the card are written in the RAM 83. The data process circuit 15 takes the exclusive 'OR' of the ROM 84 and RAM 83 and outputs processed data. The data previously written in the ROM 84 can be recognized by means of the processed data of the circuit 15. When such arrangement is made, a protect box for protecting the previously stored software can be housed in the memory card after making the box into an IC and at the same time, the software can be prevented from being copied because the content of the protect IC cannot be read out easily from the outside. |
