| 摘要 |
PURPOSE:To make readout of program data difficult and, at the same time, to prevent the rewriting of the program data by incorporating a central operation processor and one-time read-only memory (ROM) in the same chip. CONSTITUTION:A one-time ROM 14 is incorporated in one chip and the address terminal, data terminal, write enable terminal, etc., of the ROM 14 are shared with an input-output port 16. Therefore, the program data stored in the one-time ROM 14 cannot be read out unless an exclusively used ROM reader/writer 61 is used, since the terminals of the ROM 14 are arranged in a different way from the ordinary ROM. In addition, even though the program data are read out, the program data cannot be rewritten, since the program data are stored in the ROM 14. Therefore, readout of the program data becomes difficult and, at the same time, rewriting of the program data can be prevented. |
