Hitachi, Ltd.

Norikazu Takayama

Akira Kojima

Tsuneo Hirose

Nobuyoshi Ushijima

Akira Ishibashi

Hiroshi Masuda

Masahiko Sato

Toshiyuki Haruna

Tetsuzo Kobashi

Mitsuru Kubo

Yoshinobu Kudou

Kousuke Fujii

Atsushi Takayasu

Yoshinobu Kudoh

Masahiko Satou

Yoshihiko Yano

Jun Isozaki

A data transfer control apparatus for communicating data between a host device and an input/output device through a main buffer memory for temporarily holding the data, wherein a sub-buffer memory is disposed at least either between the main buffer memory and the host device or between the main buffer memory and the input/output device for temporarily storing the data, the amount of data stored in the sub-buffer memory is detected, access requests to the main buffer memory on the side of the host device or the input/output device are outputted in accordance with the detected data amount, and one of the access requests to the main buffer memory is selected in accordance with the priority order to access the main buffer memory on the basis of the selected access request.

Data transferring system between host and I/O using a main buffer with

The present invention relates to a magnetic disk control apparatus capable of utilizing a data region of a track. The data read/write controlling apparatus according to the present invention comprises a unit for serially reading a signal series constructed of a servo signal and data which has been recorded on a recording track; a unit for generating a first read/ write control signal in response to the servo signal of the read signal series; a unit for generating a second read/write control signal between the generation of the servo signal and a generation of a servo signal subsequent to the first-mentioned signal; a unit for writing given data into the data region of the recording track in response to the generation of the read/write control signal; and a unit for externally outputting data read out just after the read/write control signal is generated.

Read/write controlling apparatus for adjusting the data length of a

A control method for brushless DC motor having a rotor, a plurality of magnetic poles and coils of a plurality of phases involves sequentially applying a current to one phase for a prescribed time, stopping the current temporarily and then reapplying the current to the same phase. The state of the rise of the current when it begins to flow to the phase, is measured. The position of one of the magnetic poles located at a position opposite to the particular phase is detected based on the measured state of the rise of the current. In response to the position of the magnetic pole, it is determined whether the flow of the current is to be switched over to the following phase or not. If so, the current is switched over the following phase and the process is repeated. Constant speed control may be accomplished by reading information from a driven disk to determine speed, comparing the speed to a fixed speed, and selectively applying by time sharing a normal current, a brake current and an acceleration current.

Control system for brushless DC motor

A method of forming servo information in a magnetic disk apparatus of a sector servo system. Servo information is recorded in advance at the beginning of each of the sectors, and includes a DC erase signal, a track address signal and a burst signal. The track address signal indicates on which track of the magnetic disk the sector is located, and is formed by expressing the track address in Gray code and interleaving a dummy code into the Gray code. Servo information is recorded using an NRZI system or an RLL coding method. Servo information in which the dummy code is interleaved is decoded after the dummy code is removed at the time of demodulation.

Magnetic disk apparatus

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Odawara, Japan

Norikazu Takayama