Abstract: A preamplifier circuit for a hard disk drive system comprises a preamplifier circuit having a bias voltage circuit stage associated therewith. The preamplifier circuit further comprises a current bias boost recovery circuit operatively coupled to the bias voltage circuit stage which is configured to increase a rate of charging of a noise reduction capacitor associated with the bias voltage circuit stage. A head select boost recovery circuit is also operatively coupled to the bias voltage circuit and is configured to increase a rate of charging or discharging of a bias capacitor associated with the bias voltage circuit stage. Together the circuits allow for a concurrent head switch and current bias switch and avoids the problems associated with the prior art.

Abstract: A servo writer writes servo information to at least one disc of a head disc assembly. The servo writer includes a clock head that writes a clock track to the at least one disc and generates a clock signal when the clock head reads the clock track on the at least one disc. A servo pattern generator writes servo patterns to the at least one disc in response to the clock signal generated by the clock head reading the clock track on the at least one disc. The servo track writer also includes a phase lock loop clock generator which synchronizes to the clock track and produces the clock signal for the servo pattern generator.

Abstract: A method and data storage device determine an equalized signal-to-noise ratio in the storage device. The equalized signal-to-noise ratio is determined by generating an analog read signal, passing the read signal through an equalizer in the storage device, and sampling the equalized signal using an analog-to-digital converter in the storage device. The samples from the analog-to-digital converter are then used in the equalized signal-to-noise calculation.

Abstract: A data cartridge and method for providing a write-securable storage medium that inhibits writing. The medium comprises a write-secure-type indicator in a predefined location that indicates the medium is of a type that is susceptible to write securing. Additionally, the medium comprises a write-secure-complete indicator in a predetermined zone of the disk that is not accessible to a user. When the write-secure-complete indicator is set by a host device, the setting is irreversible and consequently the data on the medium is protected, and additional writing onto any part of the medium is permanently prevented.

Abstract: A mobile device is disclosed comprising a disk storage system comprising a disk and a head actuated over the disk, the disk comprising a data area. The mobile device further comprises a pressure-sensitive detector for detecting a pressure on the mobile device, and for detecting a decrease in the pressure on the mobile device indicating the mobile device may have been dropped. When the pressure-sensitive detector detects the decrease in the pressure, retracting circuitry within the mobile device retracts the head to a retracted position away from the data area of the disk.

Abstract: A disk drive has a channel circuit for demodulating data sectors and servo sectors stored on a rotating medium to provide data-sector data and servo-sector data. The channel circuit transmits the data-sector data and servo-sector data to a disk controller circuit in an order which is different than the order in which they are stored on a rotating medium to allow for demodulation latency while maintaining real-time updates of embedded servo information.

Abstract: In a magnetic recording device, a control element placed on a flexible wiring board between a control device and first actuators includes a plurality of actuator-driving-signal connecting terminals connected to a plurality of second actuators, an actuator-driving-signal input terminal to which driving voltage for the second actuators is input from the control device, connecting wires for connecting the actuator-driving-signal input terminal to the actuator-driving-signal connecting terminals, signal selection elements incorporated in the connecting wires, and a decoder for selecting one of the signal selection elements so that a specific actuator-driving-signal connecting terminal is connected to the actuator-driving-signal input terminal.

Abstract: A process of run-time temperature compensating bias current to a magnetoresistive read head in which a plurality of temperature ranges are defined with associated bias current values. A hysteresis range of temperatures is defined for each boundary between temperature ranges. A bias current value is selected based on the temperature range of the sensed temperature. The process is repeated. If the sensed temperature is in a different temperature range from that previously identified and the measured temperature is not in a hysteresis range at the boundary with the temperature range previously identified, the selected bias current value is based on the presently identified temperature range. If the sensed temperature is in a hysteresis range at the boundary with the temperature range previously.

Abstract: A circuit and a method of operation for detecting a bit sequence from an analog waveform representing the bit sequence and at least one other parameter associated with the analog waveform are disclosed. Detection includes digitizing the analog waveform and at least one other parameter using at least one analog to digital converter. The resulting digital numbers are synchronized in time by a plurality of registers so that the outputs of the registers always change simultaneously. The outputs of the registers are concatenated to form an address. The address is input into a read-only memory that looks up a most likely bit detected that has been predetermined for that address and stored in the read-only memory. The bits read from the read-only memory by the addresses are output periodically to form the bit sequence.

Abstract: A method and apparatus are disclosed for improving seek performance of a disc drive through adaptive servo gain adjustment. The disc drive comprises a head adjacent a rotatable disc and a servo circuit which controllably positions the head adjacent tracks defined on the disc. During a seek operation in which the servo circuit moves the head from an initial track to a destination track, the servo circuit accumulates a velocity error as a sum of a series of velocity errors each obtained as a difference between an actual velocity of the head and a corresponding desired velocity over a selected radial distance of the disc. The servo circuit additionally measures an elapsed time for the head to pass over a second selected radial distance of the disc as the head is decelerated toward the destination track. Thereafter, the servo circuit adjusts a gain of the servo circuit in relation to the accumulated velocity error and the measured elapsed time.

Abstract: A magnetic card reader for causing a magnetic card to make a move relative to a magnetic head and reproducing data on the magnetic card by the magnetic head, said magnetic card reader includes an amplifier for amplifying a magnetic signal provided by the magnetic head, a peak detection section for detecting a peak point of amplifier output from the amplifier output, a data reproduction section for reproducing digital data based on the interval between the peak points, an anomaly detection section for detecting an anomaly of the peak point interval and an output value storage section for converting the amplifier output from analog form into digital form every predetermined time and storing the provided data.

Abstract: The system for detecting the edge of a moving data storage medium measures the ambient noise level of the magneto-resistive read head when the magneto-resistive read head is completely off the magnetic tape media. The system for detecting the edge of a moving data storage medium sets a signal threshold that is a predetermined increase over the magneto-resistive read head output signal generated by the ambient noise. The system for detecting the edge of a moving data storage medium then moves the magneto-resistive read head on to the magnetic tape media, where an increase in the magneto-resistive read head output signal is generated due to the friction of the moving magnetic tape coming into contact with the magneto-resistive read head, causing an increased noise level.

Abstract: The object of the present invention is to provide a method and apparatus configured to allow an externally generated magnetic field to simultaneously erase a portion of the information on a disk, or a plurality of disks, within a magnetic storage device. The invention allows high throughput of erased magnetic storage devices, as in a mass production environment. Additionally, the invention allows a variety of magnetic storage device configurations in that the erasing is non-intrusive to the housing of the magnetic storage device and does not depend on the number of disks within the magnetic storage device.

Abstract: An information storing device and an information processing device having a memory for registering a plurality of working modes at recording/reproduction and a switching circuit for selecting one of the plurality of working modes, which select the optimum working mode automatically or by an instruction of an operator according to power supply capacity of a device of higher rank to effect recording/reproduction.

Abstract: A hard disk drive for a computer system has at least two actuators for reading data from or writing data to the disks. The actuators may be configured to support the different methods of data access required of them. For example, if large quantities of sequential data are performed, one operation uses both actuators to increase throughput. However, if mostly random operations are to be performed, then independent usage of the actuators is preferred. These two methods of usage can be supported simultaneously, and can even be dictated by the user. The tracking format of the actuators can be configured such that the next logical track is physically located under a head on a different actuator to improve sequential operation. The actuators also may be utilized in a dual-channel configuration so that data can be written to both actuators at the same time, or read back at the same time to improve throughput. In addition, either of these configurations can be selected on a transfer-by-transfer basis by the user.

Abstract: A signal processing device for analog-to-digital converting a burst signal has a feature of selecting a data bus to notify a disk control device of a conversion result via an NRZ data bus. The disk control device stores the result of the analog-to-digital conversion of the servo positional signal. The positional signal of a head of the disk device is digitized in a R/W channel. Sampling for digital conversion is performed in only a window which is defined only in the vicinity of peaks of the positional signal. The values of peaks which are obtained by sampling are averaged by an averaging circuit. This enables the influence of noise occurred outside of the window to be eliminated. Although the noise in the window is sampled, its adverse influence is suppressed by the averaging processing.

Abstract: Catastrophic failures of a write precompensation circuit are prevented from occurring without limiting the precompensation range to a small value and the range of precompensation is extended beyond limits imposed by the duty cycle of the clock signal. Catastrophic failure of the write precompensation circuit is prevented by ORing either the input or the output of the comparator and the opposite phase of the clock. The 180 degree delayed clock forces any transitions that would otherwise have been missed. The range of a write precompensation circuit is extended by ORing the clock and the clock delayed by a time td. The extended duty cycle that results is used to generate a longer precompensation delay. A technique is also provided to maintain constant duty cycle over a broad range of data rates.

Abstract: A method of indexing a rotatable disk in a direct access storage device (DASD) having a sensorless spindle motor, by monitoring spindle motor voltage to detect a pattern of commutation spikes timing separations, identifying a spindle motor index from the commutation spike pattern, and matching the spindle motor index with a servo sector index of the disk. A highpass filter is connected to a voltage output of the spindle motor, and an output of the filter is connected to a threshold triggering device. A timing-separation sequence is determined by counting clock pulses, and variations in the timing-separation sequence are compared. The rotor magnets of the spindle motor may be arranged asymmetrically to produce a large deviation in the variation of the timing-sequence. Indexing may be accomplished during servo track write for the disk.

Abstract: A disk device having access to a disk in different writing modes includes a host PC. The host PC sends a command including a data transfer rate to a controller (disk drive). When the command designating the data transfer rate is received, the writing mode employed for writing data to a disk is automatically switched. The host PC already has the transfer rate to be sent. It is unnecessary to newly prepare a special command to notify the controller in order for switching between the writing modes. Therefore, versatility will not be impaired.

Abstract: A servo control method for a storage media includes arranging a plurality of servo sectors along a circumferential direction of the disk-type storage medium without successively arranging the plurality of servo sectors in a radial direction and arranging a plurality of data sectors which are not split by the servo sectors.