Optical disk for use in an optical data recording and/or reproducing apparatus.

摘要

Compatibilities between a double-sided optical disk and a single-sided optical disk are assured when each disk is subject to data recording and reproduction operations by means of either a one-head type optical data recording and reproduction apparatus or a two-head type optical data recording and reproduction apparatus while allowing vertically inverted cartridge insertion for data recording and reproduction. Provided is an optical disk having a data recording area (25) and a volume management area (26) which includes an access mode registration area (27) for recording therein access mode data such as apparatus data representing the number of optical heads of the optical data recording and reproduction apparatus, the number of volumes of an optical disk, and sector recording order and/or track and sector recording units. Data recording and reproduction operations are effected by detecting the optical head (4A, 4B) facing each recording surface by means of a sensor (28), rotating the optical disk (1) forwardly or reversely, reading out access mode data from the access mode registration area (27), and switching signal paths between a channel data recording and reproduction circuit (7) and a laser drive circuit (8) and a signal reproduction head amplifier circuit by means of a signal selection circuit (18). <IMAGE>