Patent ID: 8683290

Claim:
A nonvolatile memory, comprising: a memory area including a data area configured to retain data and an error correction code area configured to retain an error correction code known as ECC; and a control unit configured to control access to said memory area, wherein said control unit comprises a comparison function configured to match a received read address with an address retained in at least one save area with a validity presentation block set to valid, wherein if said comparison function detects a match between said received read address with said address retained in said at least one save area at data read time, then said control unit outputs data from said corresponding address of said at least one save area, wherein, if said comparison function detects a mismatch between said received read address with said address retained in said at least one save area, then said control unit reads data from said data area and an error correction code (ECC) from said ECC area and causes an error detection and correction function to check for a data error, wherein in case of no data error, said control unit outputs data corresponding to said data from said data area, wherein upon detection of said data error, said control unit writes said address and correct data to said corresponding at least one save area, sets said validity presentation block to valid, and outputs said correct data, at least one save area configured such that an unmatched received read address, data at a designated address and a corresponding error correction code (ECC) are read from said memory area and if an error is detected in said data, then said detected error is corrected and said save area retains said corrected data corresponding to said address, wherein said validity presentation block configured to indicate whether or not said address and said correct data retained in said save area are valid, wherein, if a new address and said corrected data are entered into said save area, then said control unit sets said validity presentation block to valid, and if said data retained in said save area becomes unnecessary, then said control unit sets said validity presentation block to invalid; and a function configured to give notification that said address and correct data are added anew to said at least one save area.