Quantum Corporation

Hoa V Luong

Ronald R Moon

Michael G Machado

Gregg J Uhlendorf

Patrick M Weiher

Thomas G Cooper

Tuong T Quan

Steven G Campbell

Mark E Strysko

Curtis H Bruner

Andrew D Hospodor

Clifford M Gold

Trinh C Bui

Bryan John Mee

Hang Diem Nguyen

Minnie Uppuluri

George Li

Steve Paul

A method of coordinating access to a data buffer including a plurality of data blocks, using a buffer list with a plurality of entries corresponding to the data blocks. Each buffer list entry includes: (i) a status code for indicating the status of data in the corresponding data block, and (ii) a partial address common to both the next buffer list entry and a data block corresponding to said next buffer list entry. A status code is selected from a cyclical set of sequential status codes having a period of N, the status codes sequentially, and alternately, representing the most recent history of a data block, including: (i) full status, indicating data in the data block has been retrieved from the storage device or is to be stored to the storage device, or (ii) empty status, indicating data transferred out of the data block to a host or to the storage device. A store flag maintains a status code representing empty status, and a retrieve flag maintains a status code representing full status. When storing data into the data buffer, locating a desired buffer list entry list with an empty status code by traversing the buffer list, calculating the address of each entry using the partial address in the previous entry, until the desired entry is found. The address of the data block corresponding to the found entry is calculated and data is stored in the data block when the status code of the entry matches the store flag status code. The found entry status code is advanced once, and if the entry is last in the buffer list the store flag status code is advanced twice. Similarly, when retrieving data from the data buffer, locating a desired entry in the buffer list with a full status code by traversing the buffer list, calculating the address of each entry using the partial address in the previous entry, until the desired entry is found. The address of the data block corresponding to the found entry is calculated and data is retrieved from the data block when the status code of the entry matches the retrieve flag status code. The found entry status code is advanced once, and if the entry is last in the buffer list the retrieve flag status code is advanced twice.

Buffer management and system coordination method

A method of responding to a request for data over a bus structure, such as a SCSI bus. Upon receiving a request, a data storage device releases control of the bus and accumulates the requested data in a buffer. Before the data has been completely accumulated, the device acquires control of the bus and begins transmitting the data over the bus. The beginning of transmission occurs late enough that the transmission can occur in a single burst. If the data can be transmitted over the bus in a time period t.sub.burst, then the beginning of transmitting should begin substantially a t.sub.burst period before the time at which the buffer completes accumulating the requested data.

SCSI disk drive disconnection/reconnection timing method for reducing

A disk data storage subsystem includes a head and disk assembly. A plurality of sectors in data tracks include a servo portion containing a prerecorded pattern of a plurality of repeating, time staggered, non-phase-coherent bursts, each burst having a predetermined integral fraction radial offset relative to the other bursts. The head is positionable relative to the tracks by a voice coil in response to information derived from a servo portion, a programmed microcontroller supervisor receives operational data storage and retrieval commands from a host system with which the subsystem is operationally associated and controls the position of the head during track seeking and following operations in response to servo information read by the head from each servo portion and further in response to the commands, an interface, with an SCSI interface controller, under the control of the microcontroller supervisor receives the commands and data blocks from the host system and for sending commands, status words and data blocks to the host system, a data sequencer and memory controller under the control of the microcontroller manages flow of data blocks to and from the disk via the head.

High capacity disk file with embedded sector servo and SCSI interface

A high performance, low cost rotating disk data storage subsystem includes a head and disk assembly. A plurality of sectors in data tracks include a servo portion containing a prerecorded pattern of a plurality of repeating, time staggered, non-phase-coherent bursts, each burst having a predetermined integral fraction radial offset relative to the other bursts and having a constant frequency preamble field followed by a unique value field related to its burst spatial location. A head is positionable relative to the tracks in response to information derived from a servo portion, a programmed microcontroller supervisor for receives operational data storage and retrieval commands from a host system with which the subsystem is operationally associated and controls the position of the head during track seeking and following operations in response to servo information read by the head from each servo portion and further in response to the commands, an interface under the control of the microcontroller supervisor receives the commands and data blocks from the host system and for sending commands, status words and data blocks to the host system, a data sequencer and memory controller under the control of the microcontroller manages flow of data blocks to and from the disk via the head and stores the information read by the head means from said unique value fields for subsequent processing by the microcontroller. A servo burst pattern providing phase quadrature and absolute position information, a servo writer, a servo qualification area and a timer, a media defect management method, an amplitude measurement circuit, and a time division control program for the microcontroller are aspects of this invention.

High capacity disk file with embedded sector servo

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Milpitas, CA, United States of America

Hoa V Luong