Nonvolatile memory system

Abstract

The present invention provides a technique for preventing an erroneous write in and an erroneous erase from a nonvolatile memory, in the case of an erroneous operation of an arithmetic processor, at a low cost without providing any external circuit. A nonvolatile memory system comprises a nonvolatile memory, a volatile memory for storing a program containing an operation instruction to rewrite the contents of the nonvolatile memory, a processing device for controlling the nonvolatile memory and the volatile memory, first invalid instruction writing means for writing an invalid instruction in place of the operation instruction, at an initialization, at a predetermined address of the volatile memory for storing the operation instruction to the nonvolatile memory, control means for writing the operation instruction at the predetermined address of the volatile memory stored with the invalid instruction, before the start of the operation of the nonvolatile memory, and for operating the nonvolatile memory on the basis of the operation instruction, and second invalid instruction writing means for writing the invalid instruction at the predetermined address of the volatile memory after the execution of the operation of the nonvolatile memory.

Description

Technical field [0001] The present invention relates to a non-volatile memory system, and more particularly, to a volatile memory including a non-volatile memory, a volatile memory storing a program including an operation command to rewrite the contents of the non-volatile memory, and a control of the non-volatile memory. Non-volatile memory system of the arithmetic processing device of the volatile memory and the above-mentioned volatile memory. Background technique [0002] The IC card formed by mounting an IC chip (semiconductor integrated circuit) with a CPU, non-volatile memory, and volatile memory on a plastic-made card has a larger storage capacity than magnetic cards that are currently widely used. The data, or the ability to encrypt data to provide superior confidentiality, etc., have begun to spread. In addition, in recent years, as a non-volatile memory mounted on an IC card, an IC card equipped with a flash-type EEPROM (flash memory) capable of storing a larger amount...

AI Technical Summary

Problems solved by technology

[0022] However, in the memory device of Patent Document 1, the power supply voltage is monitored, and writing to the nonvolatile memory is prohibited only when a drop in the power supply voltage is detected. Therefore, when the power supply voltage is normal but the CPU runs out of control However, it is still impossible to prevent accidental writing to non-volatile memory

In addition, since the data protection device of Patent Document 2 requires a unit for storing the contents of the RAM at the time of initialization, in order to realize the data protection device, an external circuit needs to be provided, and it is difficult to implement at low cost.

Images