Recording/reproducing device

A recording/playback apparatus comprising:

• a disk device for recording data on a disk type recording medium;
• and an upper control unit for controlling processes such as input/output of data from/to the outside of the apparatus, reproduction and processing of data, as well as data processing such as reading and writing of the disk device, wherein
• the upper control unit includes a composite command issuance unit which issues, to the disk device, a composite command comprising a real processing command which is a processing command to be actually executed in the disk device, and a virtual command which is a processing command that is expected to be issued by the upper control unit to the disk device after the disk device has processed the real processing command, and
• the disk device comprises
• a lower control means for receiving the composite command from the upper control unit, and controlling writing or reading of digital data, and
• a recording/playback head for performing writing or reading of digital data in/from the disk type recording medium.