Abstract: A servo address is encoded in a disk drive system having at least one disk for storing data. A servo address associated with a sector in a track, or cylinder, on a surface of a disk and comprised of a sector number, a track number, and in multiple disk systems, a head number is encoded into the encoded servo address. Encoding the servo address saves disk storage space because the encoded servo address uses fewer bits than a conventional servo address while still enabling the disk drive system to locate positions on the disk.

Abstract: A disk drive stores multimedia data in long spiral data tracks. The tracks on opposite surfaces of the disk spiral in opposite directions, so that a track on one surface can be read as the actuator sweeps in, and a track on the opposite surface can be read as the actuator sweeps out. Because the actuator only follows spiral tracks without performing long seek operations, the actuator motor can be reduced in size and stresses on actuator bearings and other parts are reduced. Additionally, due to reduced disturbances associated with seeks, it is possible to follow tracks more closely and therefore reduce the width of individual tracks. Further cost reductions are accomplished by spinning the disks at a slower speed and reducing the size of the spin motor accordingly. Finally, data density can be increased simply because multimedia data does not require the same low error rate as conventional data. Preferably, a group of disk drives optimized for multimedia data is used to form a video-on-demand system.

Abstract: A digital storage system is disclosed in which a flying read/write head is loaded onto the surface of moving storage media with controlled velocity to avoid contact with the surface of the storage media. Head load velocity is detected by measuring the back EMF generated by the head arm actuator. Improved control and accuracy is obtained by breaking up the head arm actuator drive power into a series of pulses and measuring the back EMF induced into the low impedance voice coil of the head arm actuator in between pulses but only after the actuator current has been reduced to substantially zero in order to avoid interference by actuator current induced voltages.

Abstract: A servo address is encoded in a disk drive system having at least one disk for storing data. A servo address associated with a sector in a track, or cylinder, on a surface of a disk and comprised of a sector number, a track number, and in multiple disk systems, a head number is encoded into the encoded servo address. Encoding the servo address saves disk storage space because the encoded servo address uses fewer bits than a conventional servo address while still enabling the disk drive system to locate positions on the disk.

Abstract: A secondary data storage system for a host computer system includes a disk drive system having a device controller, at least a first magnetic disk and a read/write magnetic transducer positionable with respect to a recording surface of each magnetic disk. A write operation exposes data on adjacent tracks to potential damage if an off track condition occurs to the transducer during a write. A method for controlling write operations through the device controller provides backup of data in tracks adjacent to a target track for the write operation prior to the write operation occurring. The method detects occurrence of events resulting in an off track condition of the magnetic transducer relative to a target track. Occurrence of such an event triggers a determination of damage to the contents of tracks adjacent to the target track and restoration of those tracks. Write operations to the target track are blocked until shock events discontinue.

Abstract: Apparatus and method are provided for servo signal demodulation using a servo processor and a partial-response maximum-likelihood (PRML) data channel in a disk file. A servo burst timing window is identified. Then a plurality of digital samples are detected with the PRML data channel responsive to identifying the servo burst timing window. Sequential sets of the detected digital samples are accumulated by the PRML data channel and transmitted to the servo processor. The digital samples are processed by the servo processor for providing servo phase information that is used to provide servo position information.

Abstract: A spindle motor control method and apparatus for spindle motor control are provided for use in a direct access storage device. A plurality of operational modes of the direct access storage device are detected. The operational modes of the direct access storage device include start-up and idle operational modes and predetermined critical operational modes that include reading of data and reading of servo information. A pulse width modulation (PWM) mode control for applying driving current to the spindle motor is provided responsive to detecting a start-up or an idle operational mode. A linear mode control for applying driving current to the spindle motor is provided responsive to detecting one of the predetermined critical operational modes. During operation of the disk file, a small percentage of the overall file power-on time is spent performing critical file operations so that substantial power savings are achieved by the PWM mode control.

Abstract: High density magnetic disk storage and semiconductor module technologies are combined to provide a disk drive using a standard multilayer ceramic substrate as the disk drive base support member to support spindle and actuator assemblies including 1 inch diameter disks. The ceramic substrate has components and very large scale integration (VLSI) chips mounted directly thereon to avoid use of one level of packaging and presents standard pins to mount the drive using standard sockets to afford economy and reliability.

Abstract: A data processing system is disclosed having a direct access storage device (DASD) subsystem comprising a number of separate physical housings, each housing having a number of disk supporting spindles mounted therein. The velocity of rotation of the spindles within a housing is synchronized, and the rotational position of the spindles may be locked into a fixed relationship. When number N of disk supporting spindles are provided, spindle rotation is synchronized, and mirrored data files are written out of phase by 360/N degrees, thereby providing reduced latency time during a subsequent read operation, while at the same time providing data integrity through the use of redundant data files.

Abstract: A structure and organization for a magnetic disk drive provides for optimizing the volumetric storage density within a device form factor by optimizing the number of disks. The spindle and dual rotary actuators are respectively supported at each side by a pair of support plates that are separated and supported by not only the spindle and actuator shafts, but also the voice coil motor core pieces and tie plates which carry shock mounts. This head-disk assembly is shock mounted in the lower part of a two part enclosure wherein the enclosure parts are aligned and separated by elastomer guides and the separation covered by a compliant tape to complete the enclosure. Both actuators use a common servo surface while one actuator carries upwardly facing transducers and the other downwardly facing transducers so that each arm extending between disks mounts, but a single suspension-transducer assembly to reduce interdisk spacing.

Abstract: A disk file control provides for tracks having defective sectors by forming sectors as a single, uninterrupted stream of serial data containing both identifier (ID) and data portions. Reading a single ID portion characterizes the entire track to permit writing data without a separate revolution to read the ID field. The ID information includes the offset of the first logical sector on the track and the locations of defective sectors that must be skipped. As soon as one ID is read, the location of the addressed sector is ascertained and the ID data for the sector to be written is formulated so that the entire sector including both ID and data can be written when the sector first approaches the transducer. If alternate sectors are permitted on a subsequent track under the strategy being used, a single ID on the track will define where the logical sectors making up that track will appear (either the physical sector location on the track or at an alternate location on the next track).

Abstract: A high speed, small diameter disk storage system having a plurality of disk drive devices utilizing disks with a nominal 65 mm diameter rotated at a speed of approximately 10,000 RPM which can be optimally arranged in a four drive system to match the space geometry of the traditional half-high flexible disk drive used in a personal computer.