Abstract: A data transfer system makes more effective use of a band available for the data transfer. In data transfer systems having devices with a different delay time in sending back the data depending on the transfer rate of data, it is possible to make more effective use of the band available for the transfer by transferring predetermined data at a slowest transfer rate within the data transfer system.

Abstract: A data network has a bus to which are connected a given node, a parent node and a child node; and arbitration over acquisition of the bus is performed before data is communicated between nodes. Transition to an initial state in a self identification phase, in which the given node is enabled to respond to an arbitration signal received from the parent node, is controlled by receiving at the given node a SELF_ID packet representative of the child node, as well as the arbitration signal (SELF_ID_GRANT) from the parent node, which would enable the given node to transmit to the parent node a SELF_ID packet representative of the given node. The initial state is assumed at the given node, from which the SELF_ID packet is permitted to be transmitted from the given node to the parent node, if reception of the arbitration signal from the parent node is completed at the given node.

Abstract: A router emits an infrared ray based on a signal for operating a video recorder to the video recorder at a request made by any one of personal computers connected to the router through a network. In response to the infrared ray based on a signal for operating the video recorder, the video recorder outputs analog signals to the router through cables. The router then converts the analog signals into audio and video digital signals. Subsequently, the router outputs the digital signals to the personal computer making the request by way of the network. Then, the personal computer making the request outputs a sound based on the audio digital signal and displays a picture based on the video digital signal. As a result, the router allows an analog apparatus such as the video recorder to be connected to the network in a simple configuration.

Abstract: A data transfer system makes more effective use of a band available for the data transfer. In data transfer systems having devices with a different delay time in sending back the data depending on the transfer rate of data, it is possible to make more effective use of the band available for the transfer by transferring predetermined data at a slowest transfer rate within the data transfer system.

Abstract: There is provided a converting processing block 3 for carrying out a processing to convert an arbitration signal into code data of 5 bits and for carrying out 4 bit/5 bit converting processing with respect to packet data to thereby carry out transmission/reception of arbitration signal and packet data as code data of 5 bits through transmitting blocks 6A, 6B and receiving blocks 7A, 7B. Thus, there is realized an interface apparatus for digital serial data which realizes extension of cable length between nodes in the digital serial data interface (e.g., IEEE 1394 high performance serial bus standard) adapted for carrying out arbitration of bus use right prior to transfer of data, thus to permit long distance transmission.

Abstract: In the bus initialization phase, the state is transferred to the reset start state (i.e., R1 state) first, and a bus reset signal is sent to all the connected partners for a predetermined period of time determined by the reset_time (ranging from 1.26 ƒÊm at the shortest to 1.40 ƒÊm at the longest). When it is acknowledged that bus reset signals have been received from all the connected partners and a predetermined period of time has elapsed, the state is transferred to the reset wait state (R1 state). In this arrangement, there is no fear that an IDLE signal received in a reset wait state from a partner connected by use of a long cable will result in an erroneous transfer to a tree identification phase, and the bus reset signal will be received from the connected partner at the tree identification phase so as to return again to the R0 state at the bus initialization phase.

Abstract: A magneto-optical disc recording or reproducing device focusing control servo system which uses a digital signal processor (DSP) to control a pulse width modulation (PWM) circuit so that if the focusing servo is to be in operation alone, such as during a focusing search or seek, fixed clocks of a fixed frequency are used for processing focusing servo signals and after engagement of the focusing servo, focusing servo is effected responsive to focusing servo signals which are formed based upon a reproduced servo pattern of the magneto-optical disc.

Abstract: A magneto-optical disc recording or reproducing device focusing control servo system which uses a digital signal processor (DSP) to control a pulse width modulation (PWM) circuit so that if the focusing servo is to be in operation alone, such as during a focusing search or seek, fixed clocks of a fixed frequency are used for processing focusing servo signals and after engagement of the focusing servo, focusing servo is effected responsive to focusing servo signals which are formed based upon a reproduced servo pattern of the magneto-optical disc.

Abstract: An optical disk apparatus in which data is stored in internal registers of a digital signal processor need not be saved and returned when a servo processing based on an interrupt processing routine is executed. Internal registers of the digital signal processor are allocated. At least one group of the divided internal registers is exclusively allocated to the execution of a servo signal processing interrupt routine and the other groups of internal registers are exclusively allocated to execute a system control processing. With such allocations, when a sampling interrupt occurs, servo signal processing of a focus servo signal processing and a tracking servo processing is carried out without saving data from the internal registers of the digital signal processor.

Abstract: An optical recording and reproducing apparatus comprising an erroneous recording prevention component which prevents this apparatus from making an erroneous recording or erasing operation while it records data on a writable disk. The apparatus is arranged such that, while it is performing a recording or erasing operation, a state of its beam of light just about to go off the control point of tracking and a state of its beam of light just about to go off the control point of focusing are each monitored and, when either of the states is detected, the recording or erasing operation is canceled. Hence, laser power of the beam of light can be controlled before the beam of light completely goes off the control point of tracking, thereby preventing the beam of light from affecting data having been recorded along other tracks.

Abstract: A system and method for accessing tracks for an optical disc apparatus are disclosed in which when a light spot is jumped toward a target track, an acceleration pulse is applied across a fine tracking actuator to accelerate the fine tracking actuator for a predetermined period of time, a relative speed of the light spot to the tracks of the optical disc is detected though a detection of a period of a traverse signal outputted due to a movement of the fine tracking actuator, and a control signal corresponding to the relative speed is used to control the movement speed of the fine tracking actuator. Therefore, before the end of a track jump, a constant relative speed can be achieved such that a smooth tracking servo can be carried out. Consequently, an access time to access the target track can be shortened.