Abstract: An information recording and reproducing apparatus for recording information on the recording medium and reproducing the information from the recording medium has a data recording region of a sector structure in which the region is divided into a plurality of sectors. There are provided means for designating alternate sector to be used in place of a defective sector and means for adding to data a logical address of a sector where the data is to be recorded. Reproduction from the sector where the desired data is recorded can be accomplished by using only a physical address without being influenced by difference between the physical address and the logical address brought about by the occurrence of the defective sector.

Abstract: An optical disk exclusively used for reproduction has an optically detectable guide groove in which signals have previously been recorded. One type of optical disk exclusively used for reproduction is interchangeable with an optical disk which allows both recording and reproducing operations or enables information recorded thereon to be erased. If such an optical disk is not provided with a guide groove in an unrecorded region remaining between a data managing information region and a data recording region, problems may arise when the optical head of an optical disk apparatus is positioned in the unrecorded region at the time of starting the operation of the apparatus and when the optical head effects retrieval between the data managing information region and the data recording region.

Abstract: An optical information recording and reproducing apparatus for recording and reproducing information on and from an optical recording disk having an optically detectable guide track divided into a plurality of sectors is disclosed. When a sector to or from which a data is to be recorded or reproduced is a defective sector or a non-use sector because of updating, a special pattern signal is recorded on the defective sector or the non-use sector, and if the recorded special pattern signal is detected in the reproduction cycle, that sector is determined as a defective or non-use sector and recording or reproducing on or from that sector is inhibited.

Abstract: An optical information recording and reproducing apparatus for recording and reproducing information from an optical recording disc including an optically detectable guide track preliminarily divided into a plurality of sectors. In the case of an unerasable disc, if an uncorrectable error exists in any sector after data has been recorded and reproduced from the sector, it is necessary to process this sector so as to prevent further reproduction an again record the data in another sector. Also, when updating a part of the data or erasing the file, it is desirable to take a measure so that reproduction of the data in any unwanted sector is prevented. Also, in the case of any unrecorded sector involving such dropout that the recording of data is presumed to cause an uncorrectable error, it is desirable to handle it as a defective sector and process it so as to prevent the recording of data therein. In such a case, it is desirable to effect the similar process also in the case of an erasable disc.

Abstract: Apparatus for detecting and correcting errors on product codes, utilizing a product code of minimum distance 2t symbols constituted by two codes having minimum distance 2 and minimum distance t respectively. First the code of minimum distance t is decoded, and secondly error number flags generated in the decoding operation are classified into three decoding modes by statistical processing. Errors are detected or corrected according to the decoding mode.

Abstract: A data recording/reproducing apparatus which uses a recording medium having a data recording area divided into a plurality of sectors, each sector having an address section in which a first address signal is recorded and a data recording section, wherein a second address signal is added to data to be recorded, the second address signal representing an address of a sector in which the data is to be recorded, the data combined with the second address signal is encoded for error compensation and is recorded in the recording mode, and the second address signal reproduced with the data from the data recording section in the reproduction mode is used to discriminate an address of a target sector for reproduction. The sector address is obtained with the same level of precision as that of the reproduced data, thereby performing precise sector control and preventing data loss.