US Patent 7502970 Memory device and memory card

A memory device comprises a data storage section, a section which compares in write processing, for data being target of the write processing, a state before the data is stored in the data storage section with a state of the data which is stored in the data storage section and read out from the data storage section, a section which obtains the number of errors for the write processing on the basis of a comparison result from the comparison section, and a section which returns the number of errors.