Abstract: An apparatus comprises at least one port for coupling signals to the apparatus, a mode selector for setting the apparatus to a normal mode or a debug mode, and a port control for controlling access to secure information in the apparatus through the port in accordance with the selected mode. A method for controlling access to the port is also provided.

Abstract: A data storage device comprises a storage medium and a controller including a cryptographic and security module for encrypting and decrypting data to be stored in and retrieved from the storage medium. The cryptographic and security module includes an interface for receiving commands from a processor, a secret root key, an encryption and decryption unit for encrypting and decrypting data using the secret root key, a buffer access unit for receiving encrypted data from and sending encrypted data to a memory, and a command controller for controlling the encryption and decryption unit and the buffer access unit in response to commands from the processor. The command controller implements mechanisms for movement of intermediate results within the cryptographic and security module to protect intermediate and plain text results from visibility outside the cryptographic and security module.

Abstract: An apparatus comprises a circuit for generating a secret root key having bits representative of threshold voltages, and an error correction module for correcting errors in bits of the secret root key to produce a corrected secret root key. A method of generating a secret root key and a data storage system that includes a secret root key are also described.

Abstract: A method of recovering data from a data sector through adaptive fly height to improve reliability of a disc drive is disclosed. Encountering a data error in a data sector initializes an error recovery routine that increases a fly height of the read/write head for asperity encounters, or decreases the fly height of the read/write head for low amplitude read signal encounters. In the case of asperity encounters, when the increased fly height fails data recovery, the read/write head is positioned off track, then lowered to burnish the asperity and the data sector is re-read.

Abstract: A method of reducing read/write head wear and disc wear through controlling fly height of the read/write head to improve reliability of a disc drive is disclosed. Absent data transfer operations, a fly height adjusted sweep cycle routine executes a sweep cycle sub-routine that positions the read/write head at an inner most data track, lowers the fly height of the read/write head and performs a seek to the outer most data track to sweep debris from a recording surface and then raises the fly height above an operating fly height for the read/write head, oscillates the read/write head to dislodge debris accumulated on the read/write head and holds the read/write head at the raised fly height while awaiting a new data transfer operation.

Abstract: A method of recovering data from a data sector through adaptive fly height to improve reliability of a disc drive is disclosed. Encountering a data error in a data sector initializes an error recovery routine that increases a fly height of the read/write head for asperity encounters, or decreases the fly height of the read/write head for low amplitude read signal encounters. In the case of asperity encounters, when the increased fly height fails data recovery, the read/write head is positioned off track, then lowered to burnish the asperity and the data sector is re-read.

Abstract: A disc storage system having a host computer interface adapted to coupled to a host computer, a disc storage medium having a disc surface and a spindle motor coupled to the disc adapted to rotate the disc. The disc includes spare data regions and permanent data regions. A transducer is positioned for reading and writing data on the disc surface. The system further includes a controller adapted to write data on the spare data regions to thereby provide a non-volatile write cache.

Abstract: An apparatus and method for performing voltage margin testing in an integrated circuit device. The device is provided with an embedded voltage source having a voltage regulator which outputs a regulated analog voltage at a nominal magnitude, such as +3.3 volts. A voltage monitor provides an indication when the regulated analog voltage varies from the nominal magnitude by an output tolerance range determined as a first selected percentage of the nominal magnitude. An adjustment circuit applies a voltage regulator adjustment signal to the voltage regulator to adjust the regulated analog voltage by a second selected percentage of the nominal magnitude. The adjustment circuit further provides a voltage monitor adjustment signal to the voltage monitor to concurrently adjust the output tolerance range to a third selected percentage of the nominal magnitude different from the first selected percentage.

Abstract: A disc storage system having a host computer interface adapted to coupled to a host computer, a disc storage medium having a disc surface and a spindle motor coupled to the disc adapted to rotate the disc. A transducer is positioned for reading and writing data on the disc surface. The system further includes a volatile memory write cache and a non-volatile memory write cache adapted to store data during a power loss. A method is also provided for storing data prior to writing the data in a non-volatile memory cache in a disc storage system.

Abstract: An apparatus and method are disclosed for recovering from a header error condition in a disc drive of the type having a rotatable disc having a plurality of concentric tracks with data fields for the storage and retrieval of data and header fields providing logical address information for the data fields. The header fields include read and write header fields which are used during read and write operations, respectively, to align read and write elements of the head with the data fields. When the disc drive unsuccessfully decodes the logical address information from a selected header field associated with a selected data block, an alternate header error recovery routine is performed wherein attempts are made to decode the logical address information from the alternate header field associated with the selected data block. Radial offsets can further be applied to the head to enhance the decoding of the logical address information from the alternate header field.

Abstract: A temperature sensing system for use in a computer disc drive comprises a themoelectric sensor having an output sensor voltage which is variable as a function of temperature, an interface circuit adapted to receive the output sensor voltage from the thermoelectric sensor and adapted to generate a scaled and level-shifted analog output voltage signal, and an analog-to-digital converter circuit adapted to receive the analog output signal voltage from the interface circuit and convert the analog output signal voltage into a digital signal which is compared to various defined thresholds.

Abstract: A magnetic disc storage system includes a magnetic storage disc and a transducing head. During periods of inactivity the transducing head is dithered whereby the head is moved to tracks on the disc according to a number of criteria. The criteria includes wear reduction, power reduction, avoidance of textured zones, head cycling, increased fly height and clearing of debris carried on the head.

Abstract: Method and apparatus for resetting a disc drive during a disc drive reset sequence comprising a sequential three-stage reset using power valid, clocks valid and delay criteria. Input voltage provided to the disc drive is monitored to detect the presence of input voltage at a nominally acceptable voltage level, after which a system clock generator initiates generation of a system clock signal. A lock detector circuit employing a PLL circuit monitors the system clock signal and indicates when the system clock signal has achieved frequency stability by way of an output signal, which enables a counter circuit to initiate a timed delay by counting a predetermined number of the system clock signals. During the timed delay, a disc drive system microprocessor is initialized to a known, desired state and the counter provides a reset signal to the system microprocessor at the completion of the timed delay, indicating completion of the reset sequence.

Abstract: A method and apparatus for visually inspecting a discrete DIP switch block on a circuit card and analysis of the physical position of each switch. A comparison of reflected light intensities from each of the horizontally oriented switch faces is performed to determine the relative position of the switches. An output is provided based upon the comparison.