Patent ID: 7080306

Claim:
A disk device comprising: a disk drive including a head for reading data written to a disk and a processing circuit for processing the data; and a host computer connected to said disk drive through an interface; wherein the processing circuit of said disk drive includes a low-level error-correction code unit for performing error correction of the data written to a physical address corresponding to a single sector of the disk, the host computer includes a high level error correction code unit for performing error correction of the read data supplied through the interface and read from more than one sector of the disk, a high-reliability disk to which both a low-level error-correction code and a high-level error-correction code are written and a disk to which only the low-level error-correction code is written are loadable into said disk drive, when the high-reliability disk is loaded, the processing circuit of said disk drive performs low-level error correction, and then said host computer, to which the correction data is supplied, performs high level error correction, and when the latter disk is loaded, the processing circuit of said disk drive performs low-level error correction, and said host computer processes the corrected data.