Patent ID: 6851015
Filing Date: 2005-02-01
Classification: G11C

Abstract:
1. A method of overwriting nonvolatile memory data in which data of interest is stored sector by sector, comprising, when overwriting data of interest, the steps of: providing a backup region having at least the same memory capacity as one sector in which data to be overwritten is stored, said backup region being provided in non-volatile memory; writing in said backup region pre-overwrite data stored in said one sector in which data to be overwritten is stored along with an error detection code for said pre-overwrite data; copying said pre-overwrite data to a volatile memory; editing said pre-overwrite data stored in said volatile memory to produce post-overwrite data; erasing said pre-overwrite data from said one sector; then, writing in said one sector said post-overwrite data stored in said volatile memory together with an error detection code for said post-overwrite data; and upon restoration of power, determining whether the data in said one sector is valid using said error detection code.