International Business Machines Corporation

Yuji Kigami

Tsutomu Numata

Kenji Ogasawara

Takashi Nakamura

Hiroshi Uchiike

Tatsuya Sakai

Yuzo Nakagawa

Takashi Kuroda

Nobuya Matsubara

Takao Matsui

Toshio Kanai

Yuji Yokoe

Koji Kurachi

Kohji Yamada

Kenji Shimizu

Kazuyuki Ishibashi

Mayumi Okada

To realize simplification of the structure and high reliability in the disk drive. When a position of a target sector on a disk,is detected while skipping data sectors including a first region which is written using a first read/write clock (RDWTCLK) and a second region which is written using a second read/write clock, a controller,in a HDC,presets to a counter,an offset value which is based on the length of a sector to be skipped and a difference in the frequency between the first and the second RDWTCLKs and counts the first RDWTCLK fed from a CLK generator,of a channel IC,to detect the position of the target sector.

Disk unit and read/write control method

A disk drive system comprising a sector buffer having a plurality of segments for storing data and a controller for classifying data and for storing a portion of the classified data in a segment of a sector buffer such that said portion of the classified data stored in said segment is not stored in any other segment in the sector buffer.

Disk drive system using sector buffer for storing non-duplicate data in

A disk and a disk drive having a servo start mark for identifying a servo-information start position recorded on the disk is provided. The servo start mark has a plurality of bit patterns unused for other areas in servo information. A method for identifying the position of a signal transducer on a disk is also provided in which it is judged that the signal transducer is present at a predetermined position even if an error is present and the error is a one-bit error. This is accomplished by assuming that the position is correct when the following conditions are confirmed: (a) a parity error occurs in a read servo-information bit pattern and (b) read servo-information bit pattern does not coincide with servo information of an adjacent track.

Method and apparatus for indicating start of servo information on a

A programmable external storage control apparatus, including a buffer for temporarily storing data to be transferred between a host and an external storage, which stores a program for controlling data transfer between the host and the external storage and controls the data transfer between the host and the external storage by reading the data transfer control program from the buffer and executing it. The apparatus further includes a microprocessor that responds to a command from the host by starting the control of the data transfer by reading the data transfer control program. The microprocessor includes a memory for storing the data transfer control program in addition to other programs to be executed by the microprocessor. The microprocessor loads the data transfer control program from the memory into the buffer at the time of initialization. This allows the microprocessor to do other jobs such as servo control while the data transfer control program is executed.

Programmable external storage control apparatus

A disk drive having embedded servo information accesses data without using sector identifier recorded in each sector. When a signal sector pulse signal (SP) at the end of a servo area is detected in a dead state during start up, a first data state for the start of a sector transits to a second data state for the litter region of the sector being divided in accordance with the capacity stored in a current sector's pointer register. At the beginning of the sector, the contents of a next sector's pointer register is stored in current sector's pointer register and the contents of a next sector's operation register is stored in a current sector's operation register. Upon completion of sector processing, the first data state is maintained when the next sector is contiguous. When a terminate instruction is stored in current sector's operation register, the process moves to dead state. When the servo area arrives, the process moves to idle state. Responsive to this state, the magnetic head is activated to enable read and write operation for sectors having no sector identifier on the disk.

Information recording disk and drive system using no sector ID to

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Yamato, Japan

Yuji Kigami