Recording/reproducing device

A recording/playback apparatus comprising:

• a disk device operable to record data on a disk type recording medium;
• and
• an upper control unit operable to control processes of at least one of input/output of data from/to the outside of said apparatus, reproduction and processing of data, and data processing of at least one of reading and writing of said disk device;
• wherein:
• said upper control unit includes a composite command issuance unit which is operable to issue, to said disk device, a composite command comprising a real processing command, which is a processing command to be actually executed in said disk device, and a virtual command, which is a processing command that is expected to be issued by said upper control unit to said disk device after said disk device has processed the real processing command;
• and
• said disk device comprises
• a lower control unit operable to receive the composite command from said upper control unit, and to control at least one of writing and reading of digital data, and
• a recording/playback head operable to perform at least one of writing and reading of digital data in/from the disk type recording medium,
• wherein said lower control unit includes a virtual command reception unit which is operable to notify said upper control unit that the process corresponding to the real processing command is completed on the basis of a completion of the real processing command, to receive the virtual command of the composite command, and to control said disk device to move a process corresponding to the virtual command and to then standby, and
• wherein the process corresponding to the virtual command is a process up to a point of time when said disk device cannot continue the operation thereof unless the virtual command is changed to the real processing command.