Abstract: A mobile communication system is provided that can increase the number of radio base stations undergoing the group control, and enable multichannel connection without modifying a hardware configuration and without concentrating a control load on a master base station. In the system, only the master base station includes a radio circuit control channel controller for controlling radio circuit side control channels. Individual radio base stations including the master base station, which constitute a group control base station complex, each include a wired circuit control channel controller for controlling a wired circuit side control channel.

Abstract: Functions regarding a mechanical structure are made common so as to enable both of a CD and an MO cartridge to be used by one apparatus. When the CD as an exposed medium is loaded, the apparatus operates as a CD player. When the MO cartridge as a cartridge enclosed medium is loaded, the apparatus operates as an optical disk drive.

Abstract: A constant linear velocity control (CLV control) for controlling a spindle motor so as to set a linear velocity in a track circumferential direction to be constant and a constant angular velocity control (CAV control) for controlling the spindle motor so as to set a rotation of a medium to be constant are switched and controlled for a change in position in the radial direction of the medium of a pickup in accordance with a detection result of the medium loaded. In the switching control, selection information of the CLV control and the CAV control is previously registered in accordance with the kind of medium and the CLV control or the CAV control is selected in accordance with the corresponding selection information obtained from the detection result of the medium.

Abstract: A first host interface circuit for an MO and a second host interface circuit for a CD are provided in order to allowing a common apparatus of two kinds of medium to be seemed as independent drives, for example, a CD player and an MO drive for a host. The first host interface circuit for the MO and the second host interface circuit for the CD are allocated to a master and a slave by peculiar ID numbers in a host interface. The first host interface circuit for the MO executes a reception of a command for the MO from and a response to the host interface. The second host interface circuit for the CD executes a reception of a command for the CD from and a response to the host interface.

Abstract: A CD and an MO cartridge are accessed by a pickup of the same optical system, thereby allowing 4-split photodetectors to receive a medium return light to obtain a tracking error detection signal. Upon recording and reproduction of the MO cartridge, a tracking error detecting circuit for MO detects a first tracking error signal by a push-pull method on the basis of light reception signals obtained from the pickup. Upon reproduction of the CD, a tracking error detecting circuit for CD detects a second tracking error signal by a heterodyne method on the basis of the light reception signals obtained from the pickup.