Abstract: Optical information recording medium in which, information of a data format constructed by an ID section and a data section can be recorded and regenerated from both regions of a land portion and a groove portion formed on a disk face. Information such as an address is recorded to the ID section as a format by a PPM recording system when information is recorded to the data section by a PWM recording system. The information recording medium may have a land portion and a groove portion formed in a spiral or concentric shape. A land mark may be formed in a position information section of the land portion and constructed by a pit recorded as position information, and a groove mark may be formed in a position information section of the groove portion. The groove mark may be constructed using an interrupting portion between grooves and recorded as independent position information different from the position information of the land portion.

Abstract: A reference clock frequency divider feasible for a motor drive IC (Integrated Circuit), optical disk drive, hard disk drive or similar apparatus. The frequency divider is capable of setting not only integral frequency division ratios but also decimal frequency division ratios without any circuit modification.