Cirrus Logic Inc.

Son H Ho

Petro Estakhri

Paul M Romano

John S Geldman

Larry D King

Phuc Tran

Maryam Imam

Siamack Nemazie

John J Schadegg

Mike Machado

Christopher P Zook

Bhupendra K Ahuja

Petro Estakhrf

Hien Nguyen

Palaksha Setty

Ronald M Yamada

Sunil Bhaskar Chaudhari

An apparatus and method for disk sector layout, formatting, reading and writing, is based on a flexible formatter microengine that is driven by parameter lists, which may include commands to dynamically download the microengine's writable control store during disk access operations. This reduces the intervention required by the local microprocessor to support exception handling, including defect management, thus decreasing total access time for typical disk access (format, write or read) operations. This also reduces or eliminates the area on the disk required for ID fields, thus increasing the storage capacity of disk drives controlled by the present invention. This also increases disk space utilization, thus increasing the storage capacity of a disk drive controlled by using the present invention. Additionally, the invention is based on ID fields that may contain redundant information for increased fault tolerance. Additionally, the invention supports split data fields while minimizing the amount of additional information that the ID fields must contain about the data field split sizes. Alternatively, the invention supports eliminating ID fields entirely with the prior art functions of ID fields taken over by a combination of parameter lists and sector status flags.

Disk drive control without identification fields

A table driven method and apparatus for automatic split field processing in a disk drive system stores data representing the split fields after each servo mark of a frame. Each track of the disk drive system is divided up into frames or groups of sectors or equivalently servo marks, each frame comprising a predetermined number N of sectors and a predetermined number M of servo marks. Beginning from the INDEX mark, after every N sectors or equivalently M servo marks, the next sector must start after the next servo mark. The value N is a constant within each zone on a disk but can vary from zone to zone as the storage density changes. The information for each servo mark within a frame is stored in a frame table in the buffer memory. A starting address pointer and an ending address pointer are used to keep track of the starting and ending addresses, respectively, of the frame table. An address pointer is used to point to the current entry of interest in the frame table. For each servo mark within the frame, a sector pulse counter is stored, representing the number of sector pulses between the current servo mark and the next servo mark. A first time delay DY1, representing the delay from the current servo mark to the first sector pulse to be generated and a second delay value DYS, representing the size of the last split field before the next servo mark are also stored.

Table driven method and apparatus for automatic split field processing

An apparatus and method for disk-sector layout, formatting, reading and writing, is based on a flexible formatter microengine that is driven by parameter lists, which may include commands to dynamically down load the microengine's writable control store during disk access operations. This reduces the intervention required by the local microprocessor to support exception handling, including defect management, thus decreasing total access time for typical disk access (format, write or read) operations. This also reduces or eliminates the area on the disk required for ID fields, thus increasing the storage capacity of disk drives controlled by the present invention. This also increases disk space utilization, thus increasing the storage capacity of a disk drive controlled by using the present invention. Additionally, the invention is based on ID fields that may contain redundant information for increased fault tolerance. Additionally, the invention supports split data fields while minimizing the amount of additional information that the ID fields must contain about the data-field split sizes. Alternatively, the invention supports eliminating ID fields entirely with the prior-art functions of ID fields taken over by a combination of parameter lists and sector status flags.

Defect management and split field processing in disk storage systems

A method and apparatus for detecting the transfer of a wrong sector uses the LBA to ensure that a correct sector is transferred. The LBA may be appended to the sector data during a write operation and verified during a read operation. Preferably, the LBA is embedded into the CRC block during a write operation and used to detect the transfer of a wrong sector during a read operation. The LBA may be embedded within the CRC, before or after it is transmitted to a CRC Generator/Checker, by Exclusive-ORing the sector data or CRC data with the LBA. During a read operation, the incoming CRC is Exclusive-ORed with the expected LBA of the sector being read, thereby eliminating the LBA from the CRC data. The CRC data is then checked by the CRC Generator/Checker and an error is signalled if the CRC data does not match. Using the method and apparatus of the present invention, the LBA may also be embedded in the CRC during format and minimal latency operations. Off-line sector identification is performed by extracting the LBA from the CRC for formats with and without an ID field.

Method and apparatus for detecting the transfer of a wrong sector

A test logic circuit for testing the functioning of an integrated circuit containing asynchronous logic and synchronous logic and state machines is provided with a comparison circuit that compares state numbers produced by one of the state machines to a defined target value. The comparison circuit asserts a signal when one of the state numbers is equal to the defined target value. Status latches are coupled to the comparison circuit and latch a status of the asynchronous logic in response to the assertion of the signal by the comparison circuit. The comparing of the state numbers to a defined target value by the comparison circuit in the test logic circuit allows the latching of the status of the asynchronous logic upon the state machine reaching the specified state, and thereby provides the speed necessary to determine the status of the asynchronous logic for a particular state of a state machine in the integrated circuit.

Test logic circuit and method for verifying internal logic of an

An integrated circuit controls the low level, electromechanical functionality of a computer mass storage device, such as a magnetic disk drive incorporating a spindle motor for rotatably controlling a disk and an actuator for positioning at least one read/write head with respect to the disk, to read or write encoded data configured in information data sectors and to sense encoded data of servo data sectors. A servo subsystem is coupled to an output of the read/write head for detecting the servo data sectors and providing a control signal in response thereto. An analog-to-digital subsystem is also coupled to an output of the read/write head and is operative in response to the servo subsystem control signal for converting the encoded data of the servo data sectors to digital transducer position information representative of a position of the read/write head with respect to the data tracks. A data processing subsystem is coupled to the analog-to-digital subsystem for processing the digital transducer position information and providing digital motion control signals in response thereto. A digital-to-analog subsystem is coupled to the data processing subsystem for providing analog control signals to the spindle motor and the actuator in response to the digital motion control signals.

Integrated circuit servo system control for computer mass storage device

A burst magnitude comparator and an instruction sequencer are employed in a servo system controller to rapidly determine position correction information for moving a transducer head over the center line of a track recorded on a disk in a mass storage disk drive. The burst magnitude comparator selects at least two burst signals derived from bursts recorded at predetermined locations relative to the center line from which to derive a correction control signal, based on a predetermined relationship of the burst signals, and supplies the selected burst signals in a predetermined order to facilitate calculation of the correction signal by a data processor used with the servo system controller. An instruction sequencer controls a sequence of converting the analog burst signals from the head to digital burst signals without intervention or control from the data processor. By ordering the signals with the burst magnitude comparator and by sequencing the conversion of the signals, the calculation is speeded and the processing and code requirements for the data processor are greatly reduced, thereby reducing transport delay and freeing the resources of the processor for use in other, potentially more important tasks associated with the servo controller.

Burst comparison and sequential technique for determining servo control

A servo system controller for a disk drive device which includes a rotating mass storage disk incorporates a timing error determining circuit for determining rotational speed variations in the disk from information contained in a servo field recorded in a track. A timing error signal is supplied when the speed variation exceeds a threshold, thus indicating an unacceptable level of speed variation. A digital synchronizer responds to asynchronous servo data signals from the disk to establish a cell clock signal occurring about a normal frequency, a cell during which only one servo data signal will occur, and a cell data signal which occurs during the cell. The cell clock signal clocks logical operations on a synchronous basis, and servo data signals are reliably captured. A concurrence determining circuit determines the degree of concurrence between the predetermined series of cell data signals and an actual pattern of signals derived from the servo field, and recognizes the servo control information from less than complete concurrence of the derived pattern and the actual expected pattern. Normal operation is permitted even through slight inconsistences may be detected, improving data throughput while still achieving an adequate level of error tolerance.

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Sunnyvale, CA, United States of America

Son H Ho