Abstract: To enable a physically rewritable disc to be appropriately used as a write-once type. When the rewritable disc is used in rewritable application, the position where writing of a predetermined data unit (for example, an ECC block) in data is started is set to a first position with respect to a reference position to record or play back the data. In contrast, when the rewritable disc is used in write-once application, the position where writing of the predetermined data unit in the data is started is set to a second position different from first position to record or play back the data.

Abstract: To enable a physically rewritable disc to be appropriately used as a write-once type. When the rewritable disc is used in rewritable application, the position where writing of a predetermined data unit (for example, an ECC block) in data is started is set to a first position with respect to a reference position to record or play back the data. In contrast, when the rewritable disc is used in write-once application, the position where writing of the predetermined data unit in the data is started is set to a second position different from first position to record or play back the data.

Abstract: A recording medium as a physically rewritable disk is appropriately used as a write-once type. In order to use the rewritable media in write-once applications, the recording medium in the data structure thereof includes, in a second data unit (an ECC block of 64 Kbytes), flag information WF1-WF4 indicating whether a first data unit (2 Kbytes) is stored. More specifically, whether a plurality of first data units (a sector handled by a host) has been recorded in the second data unit (a recording unit sector on the recording medium) is directly indicated. When an access request is issued in emulation in a disk drive device, the flag information is referenced, and the disk drive device determines whether one of writing or reading of the first data unit as a target responsive to a command is enabled.

Abstract: In an optical disk, address information, including an address information start mark, is recorded in a header region primarily based on variable-length codes such that, between each pair of nearest bits having a first logic value, at least two and at most seven bits having a second logic value are disposed. The address information start mark is detected based on a first criterion that a combination of pulse widths each defined in association with a nearest pair of bits having the first logic value is present in a pulse sequence, and also based on a second criterion that, when the logic level of the pulse sequence alternates between a first logic level and a second logic level in association with occurrence of bits having the first logic value intermittently disposed among bits having the second logic value, the logic levels of pulses in the pulse sequence coincide with their respective counterparts in the combination of pulse widths.

Abstract: An optical disk apparatus for a phase-change optical disk detects the boundary between a first region and a second region prior to detecting a synchronization mark. The synchronization mark is detected in accordance with the position of the detected boundary between the first region and the second region. User data is read from a data region in accordance with the detected synchronization mark.

Abstract: Pieces of address information are recorded on an optical disc such that they are successively continuous addresses within each zone but discontinuous at a beginning of a zone next to the previous zone, and an address after repeating the addresses of the previous zone for two rounds becomes the forefront address of the zone next to the previous zone. Access to the land tracks is performed by returning to the first address position in a zone after the addresses of the groove tracks become the last address of the zone, and the access is performed by recognizing an address continued from the last address of the groove tracks suppositionally on the pieces of address information recorded on the groove tracks, and then the access is successively performed to move to the next zone after the addresses of the land tracks become the last address of the zone.

Abstract: In an optical disk, address information, including an address information start mark, is recorded in a header region primarily based on variable-length codes such that, between each pair of nearest bits having a first logic value, at least two and at most seven bits having a second logic value are disposed. The address information start mark is detected based on a first criterion that a combination of pulse widths each defined in association with a nearest pair of bits having the first logic value is present in a pulse sequence, and also based on a second criterion that, when the logic level of the pulse sequence alternates between a first logic level and a second logic level in association with occurrence of bits having the first logic value intermittently disposed among bits having the second logic value, the logic levels of pulses in the pulse sequence coincide with their respective counterparts in the combination of pulse widths.

Abstract: An optical disk apparatus for a phase-change optical disk detects the boundary between a first region and a second region prior to detecting a synchronization mark. The synchronization mark is detected in accordance with the position of the detected boundary between the first region and the second region. User data is read from a data region in accordance with the detected synchronization mark.

Abstract: Pieces of address information are recorded on an optical disc such that they are successively continuous addresses within each zone but discontinuous at a beginning of a zone next to the previous zone, and an address after repeating the addresses of the previous zone for two rounds becomes the forefront address of the zone next to the previous zone. Access to the land tracks is performed by returning to the first address position in a zone after the addresses of the groove tracks become the last address of the zone, and the access is performed by recognizing an address continued from the last address of the groove tracks suppositionally on the pieces of address information recorded on the groove tracks, and then the access is successively performed to move to the next zone after the addresses of the land tracks become the last address of the zone.