WRITE PROTECTION METHOD OF INTEGRATED MEMORY CIRCUIT AND CORRESPONDING INTEGRATED MEMORY CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a writing protective method for an integrated memory circuit and an integrated memory circuit corresponding thereto in which the contents of a memory cell cannot be corrected or changed by providing a pseudo random generator and a counter in an integrated circuit. SOLUTION: This integrated circuit has a microprocessor uP, a read-only memory ROM and a nonvolatile read-write memory M. The microprocessor uP is adopted as an external interface and receives various signals of a logical voltage Vcc , an electric quantity Vss , a clock signal Clk , an integrated circuit reinitializing signal Rsi and two series input/output data signals IO1 and IO2 . Further, it has a pseudo random generator 8 and a counter 9, and the pseudo random generator 8 is supplied with a physical change quantity Ve, thereby generating a random value in response to a writing command. Also, the counter 9 subtracts the radom value to initialize a counting loop.