EEPROM SECRECY HOLDING CIRCUIT

摘要

PURPOSE:To hold the data and secrecy of an EEPROM by providing a cipher memory part to an EEPROM memory cell array to compare both input data with each other and then inhibiting the rewriting and reading of data when no coincidence is secured between both data. CONSTITUTION:Specific data is previously written on cipher data memory part and it is required to input the cipher data to input/output terminals I/O 0-7 before writing/erasing and reading cycles of an EEPROM memory cell array part 1. A data comparison part 2 compares the data stored in the cipher data memory part with the data given to the input/output terminal. Then the rewriting and reading actions are inhibited by a rewriting/reading inhibiting circuit 3 if no coincidence is obtained between said both data. Then the rewriting/reading actions are allowed only when coincidence is secured between both data.