| 摘要 |
PURPOSE:To ensure the secret protection and test functions of a built-in memory by producing the read-out memory information and the expected value used for decision of the propriety of said memory information via the same information converting circuit. CONSTITUTION:In a microcomputer MCU the read data RD is converted into the read data RD' by an information converting circuit TB for the purpose of protection of a program stored in an EPROM. Then the data RD' is transmitted through a specific input/output port PO. At the same time, a writing device WRD which writes the information into the EPROM contains an information converting circuits TB' of the same constitution as the circuit TB so as to verify the writing job, i.e., to perform a test that decides whether the write data is correctly stored or not. |
