Abstract: A system for a nonvolatile memory for broad temperature range applications. The system includes a memory organized into an addressable memory range and comprising a plurality of memory arrays comprising memory cells wherein each memory array is configured for operation over a different temperature range, and a buffer for receiving a data word and an associated address for writing into the memory. A temperature sensor is used for sensing a current temperature of operation of the memory. A write controller is coupled to the buffer, the temperature sensor and the memory. The write controller is operable to perform a write operation that includes accessing a temperature value from the temperature sensor, selecting a selected memory array of the plurality of memory arrays that is configured for operation at the temperature value, and writing the data word, at the associated address, to the selected memory array.

Abstract: A system for a nonvolatile memory for broad temperature range applications. The system includes a memory organized into an addressable memory range and comprising a plurality of memory arrays comprising memory cells wherein each memory array is configured for operation over a different temperature range, and a buffer for receiving a data word and an associated address for writing into the memory. A temperature sensor is used for sensing a current temperature of operation of the memory. A write controller is coupled to the buffer, the temperature sensor and the memory. The write controller is operable to perform a write operation that includes accessing a temperature value from the temperature sensor, selecting a selected memory array of the plurality of memory arrays that is configured for operation at the temperature value, and writing the data word, at the associated address, to the selected memory array.

Abstract: According to a broad aspect of the invention, a method and apparatus are presented for identifying a track (42) of a rotating disk (12) of a mass data storage device (10), using EPR4 data detection techniques. The track identification indicia (64) may be written more densely than the track identification indicia would have been written without using EPR4 data equalization techniques, wherein track identification indicia pulses (110-113) may at least partially overlap. The identification indicia (110-113) is read from the disk (12) using a read head (18), and processed using EPR4 data equalization techniques in an EPR4 Viterbi detector (92). The Viterbi detector (92) may be used also to detect data pulses (64) by switching its mode of operation from a track identification mode to a data detection mode.

Abstract: A method and apparatus for characterizing a magnetic disk (40) of the type that contains data to be read by a magneto-resistive type head (18) in proximity thereto is disclosed. The method includes writing a continuous signal onto the disk, and reading back the signal written onto the disk (40) using the magneto-resistive type head (18). The read back signal is compared to a threshold value (58), and areas of said disk at which energy contained in said read back signal occurs above said threshold value (54) are mapped. The energy content is measured by accumulating oversampled signal values from the read back signal during a time at which said read back signal exceeds the threshold value (58).

Abstract: A method and apparatus for characterizing asymmetries of a magneto-resistive type head in proximity to a magnetic media such as a magnetic disk of a hard disk drive. The method includes using the magneto-resistive type head to read a continuous signal from the magnetic media to provide a read back signal. Energies contained in the read back signal which occur in excess of a predetermined threshold for the positive and negative portions of the read back signal are then determined. The energies may be determined by accumulating sampled signal values from the read back signal in registers during times at which the read back signal exceeds the threshold.

Abstract: A method and apparatus are disclosed for characterizing asymmetries of a magneto-resistive type head (18) in proximity to a magnetic media (40) such as a magnetic disk of a hard disk drive (12). The method includes using the magneto-resistive type head (18) to read a continuous signal from the magnetic media (40) to provide a read back signal (110, 112). Energies contained in the read back signal which occur in excess of a predetermined threshold (111, 58) for the positive (110) and negative (112) portions of the read back signal are then determined. The energies may be determined by accumulating sampled signal values from the read back signal in registers (78) during times at which the read back signal exceeds the threshold (111, 58).

Abstract: A method and apparatus for characterizing a magnetic disk (40) of the type that contains data to be read by a magneto-resistive type head (18) in proximity thereto is disclosed. The method includes writing a continuous signal onto the disk, and reading back the signal written onto the disk (40) using the magneto-resistive type head (18). The read back signal is compared to a threshold value (58), and areas of said disk at which energy contained in said read back signal occurs above said threshold value (54) are mapped. The energy content is measured by accumulating oversampled signal values from the read back signal during a time at which said read back signal exceeds the threshold value (58).

Abstract: A method and apparatus for identifying a track (42) of a rotating disk (12) of a mass data storage device (10) uses EPR4 data detection techniques. The values of the encoded track identification indicia are selected so that they have a distance between any two track identification codewords that is larger than the minimum distance of the codeset from which they were selected. The identification indicia (110-113) are read from the disk (12) using a read head (18), and processed using EPR4 data equalization techniques in an EPR4 Viterbi detector (92). The Viterbi detector (92) may have a trellis in which data paths of minimum distance of the codeset from which the track identification indicia (110-113) were selected do not exist. The Viterbi detector (92) may be used also to detect data pulses (64) by switching its mode of operation from a track identification mode to a data detection mode.

Abstract: A hard disk drive system (10) includes a read head (21) for reading information from a rotating magnetic disk (12). The read head outputs a servo burst signal in response to servo information (59) on the disk. An analog-to-digital converter (33) is provided to oversample the servo burst signal during each of a plurality of successive time intervals, in order to obtain a plurality of samples for each such time interval. An accumulator (74) is provided to sum the samples for each time interval, in order to obtain for each time interval a respective accumulation value that represents an integration of the burst signal for that time interval. A filtering circuit (86) is provided to determine a burst value for the servo burst signal, by applying a filtering function to a set of the accumulation values. The filtering function may involve determining a median accumulation value from the set of accumulation values, or determining a mean of the accumulation values in the set.

Abstract: A detection device for detecting a pattern and determining valid patterns by a series of tests. These tests include rejecting patterns based on minimum Hamming distance, spectral energies that are not concentrated with a predetermined ideal spectrum, that are not valid predetermined valid codewords, patterns that are not anti-symmetric and that have closest transition spacing.