Patent ID: 8001447

Claim:
A data storage device comprising: a disk storage medium having a plurality of sectors containing data; a head for performing a writing process or a reading process into or from said disk storage medium upon a write command or a read command transferred from a host; and error correcting means for performing an error correction process to correct an error that occurs in said data during said reading process; wherein said error correcting means performs the error correction, using a first error correcting code appended to each of a plurality of sectors and a second error correcting code appended to a predetermined sector for every block of sectors composed of a predetermined number of sectors, said second error correcting code having a greater correction capability than said first error correcting code, and further comprises: a CRC generating circuit for generating and holding a cyclic redundancy check code (CRC) based on data subjected to error correction, for checking the content of error correction; a CRC holding circuit for holding said CRC generated by said CRC generating circuit at read time if the data is uncorrectable by said first error correcting code; a verifying CRC selection circuit for selecting said CRC held in either said CRC generating circuit or said CRC holding circuit, the verifying CRC selection circuit selecting said CRC held in said CRC generating circuit if error correction using said first error correcting code is performed, the verifying CRC selection circuit selecting said CRC held in said CRC holding circuit if the data is uncorrectable using said first error correcting code; and a CRC verification circuit for verifying the content of error correction using said CRC selected by said verifying CRC selection circuit.