READ PREVENTION CIRCUIT FOR ROM

摘要

PURPOSE: A read protected circuit of a non-volatile memory is provided to prevent a reading operation for a program of a non-volatile memory by modifying an address signal applied according to a scramble weight bit and an address of a practical memory cell. CONSTITUTION: A scramble weight bit generation unit(12) outputs data according to a predetermined program. A storage unit(10) stores the data from the scramble weight bit generation unit(12). An address coding unit(11) outputs an address different from an external request address by combining the data stored in the storage unit(10) and an external address signal to generate a coded address signal. Only a certified user obtains normal data by reading the output result of the address coding unit(12).