Abstract: A frequency demodulating circuit for demodulating a frequency-modulated signal expressing digital data. The circuit includes a waveform shaping circuit for acquiring a binary signal from the frequency-modulated signal and a detector for decoding the binary signal and response to clock signals to obtain the digital data. A circuit also includes a clock signal generating circuit for generating the clock signals which have a frequency of the frequency-modulated signal corresponding to “one” of the digital data and a frequency higher than the frequency of the frequency-modulated signal by a multiple, which corresponds to a “zero” of the digital data.

Abstract: Improving the efficiency of processing isochronous data in isochronous transmission by use of a 1394-brigde. A forward stream bit of an isochronous reception context control register of a 1394OHIC unit 124a is set at 1 to thereby provide a common format such that each isochronous channel of reception data stored in a memory 112 may have the same header information as transmission data. A CPU 111 confirms that the forward stream bit of an isochronous transmission context control register of a 1394OHCI 124b has been set at 1 and then prepares each isochronous channel of transmission data without treating the data only by deleting information necessary only at the time of reception (i.e., time information and information indicating a reception state) from each channel of data to be transmitted stored in the memory 112.

Abstract: To make it possible to transmit a transmission packet which always includes correct information for identifying a transmission end. In a bridge portal 103b, a transmission packet, which is transmitted from a 13940HCI section 124b to a Link section 125b, is made to include transmission end information for indicating whether the transmission end of the transmission packet is a self-node, or the transmission end thereof is another node residing in another bus. When an asynchronous data packet is produced in the Link section 125b based on the transmission packet, if another node is a transmission end, the node ID of another node included in the transmission packet is used as a source ID. Contrarily, if the self-node is a transmission end, the node ID of the self-node is used. In this manner, it becomes possible to transmit an asynchronous data packet which always include the node ID of the correct transmission end to the 1394-bus 102 (Bus #2).

Abstract: A frequency demodulating circuit, optical disk and preformatting device having a decoder for decoding a bit “0” and a bit “1” for reproducing address information recorded as a wobble groove. The decoder determines whether an output is a digital “1” or a digital “0” so that even if the waveform of the reproduced signal is erratic or unstable due to a defect, a digital “1” or a digital “0” can be correctly identified by utilizing window pulses. Changes in the slop of a zero cross point of the groove wobble are prevented from occurring by making the groove wobble amplitude fluctuate according to the signal frequency modulation which also greatly reduces jitter and allowing satisfactory acquisition of the address information. Oversampling clock signals of biphase bits are generated by frequency division of data clock signals.

Abstract: A disk shaped recording medium, drive apparatus and method for driving a medium divided into at least a recordable area and a reproduction only area, are disclosed. Address conversion is carried out by a conversion table so that the leading portion of a logical block address (LBA) when an optical disc is viewed from the host computer side is caused to correspond to the leading physical block address PBA1=RAM_START of a random access memory (RAM) area of the outermost circumferential side of the optical disc. Thus, reproduction can be started from the leading portion of a RAM area disposed at the innermost circumferential side. Even if a read only memory (ROM) area is disposed at the outermost circumferential side, this optical disc can be used as boot device. In addition, since the ROM area can be disposed at the outermost circumferential side, data transfer speed of the ROM area is permitted to be high data transfer speed in an optical disc employing a zone constant angular velocity (CAV) system.

Abstract: A disc drive unit for driving a disc recording medium such as a magneto-optical disc accommodated in a disc cassette, comprises a chassis, a cassette holder having a pair of wall sections and moveable up and down between upper and lower positions with respect to the chassis, and the disc cassette being injectable into and ejectable from the cassette holder, a disc rotating mechanism being moveable up and down between upper and lower positions with respect to the chassis and chucked with the disc recording medium for rotatively driving the disc recording medium, height-level positioning members provided at the chassis, so that at least their upper ends are located at a higher level than the lower wall section of the cassette holder, when the cassette holder is held at its lower position, and a loading motor unit for shifting the cassette holder from its upper position to its lower position and for shifting the disc rotating mechanism from its lower position to its upper position, during loading of the disc cas

Abstract: A disc drive unit for a magneto-optical disc accommodated in a disc cassette, comprises a magnetic head for applying a magnetic field to the magneto-optical disc, a magnetic head moving mechanism for moving the magnetic head between a loading and unloading position, an eject mechanism for ejecting the disc cassette, a reversible motor, and a transmission device for transmitting a rotational force of the reversible motor to the magnetic-head moving mechanism by rotation of the motor in its one rotational direction and for transmitting the rotational force of the reversible motor to the eject mechanism in its other rotational direction whereby a controller is provided for controlling the reversible motor so that a rotational speed of the motor in the other rotational direction used for the eject mechanism is faster that the rotational speed of the reversible motor in the one rotational direction used for the magnetic-head moving mechanism in order to ensure the quick ejection of the disc cassette.

Abstract: A method of accessing a disc-shaped recording medium including the steps of (a) recording defect information on the disc-shaped recording medium including a first logical address data of defective sectors, the first logical address data being a serial logical address data assigned to all sectors including both effective and defective sectors, (b) recording on a predetermined physical location of the disc-shaped recording medium disc information containing recorded physical position information of the defect information which represents a physical data structure, (c) reading out the disc information from the disc-shaped recording medium, (d) reading out the defect information using the physical recorded position information contained in the disc information read out at step (c), (e) generating a first table using the defect information which is used to convert the first logical address data into a second logical address data, the second logical address data being an address data assigned only to the effective

Abstract: A disc driving apparatus using SSA (sector slipping algorithm) for defective sectors and LRA (linear replacement algorithm). This disc driving apparatus is simple in arrangement and can reproduce data at high speed in a simple processing on the basis of attribute data representing whether a defective sector is processed by the SSA or the LRA. This disc driving apparatus includes an optical head for reproducing data recorded in an optical disc, a drive controller for controlling operation of the optical head, a memory for temporarily storing reproduced data, a DMA (dynamic memory access) controller for controlling an access to the memory, and a system controller for controlling the drive controller and the DMA controller by supplying first and second command signals thereto in response to a main command signal requesting a write or read operation on a series of sectors.

Abstract: A disc driving apparatus using SSA (sector slipping algorithm) and LRA (linear replacement algorithm) for defective sectors. This disc driving apparatus is simple in arrangement and can reproduce data at high speed in a simple processing on the basis of attribute data representing whether a defective sector is processed by the SSA or the LRA. This disc driving apparatus includes an optical head for reproducing data recorded in an optical disc, drive controller for controlling operation of the optical head, a memory for temporarily storing reproduced data, a DMA (dynamic memory access) controller for controlling access to the memory, and a system controller for controlling the drive controller and the DMA controller by supplying first and second command signals thereto in response to a main command signal requesting a write or read operation on a series of sectors.