A first tone is written at a first frequency to outer tracks that surround an inner track of a magnetic recording medium. A second tone is written at a second frequency different from the first frequency to the inner track. The first and second frequencies are both lower than a frequency of an AC erase signal. A crosstrack profile of the inner track is determined based on reading amplitude of the second frequency via the read/write head.

This application includes systems and techniques relating to storage devices, such as a device including: a first read channel to process a first input signal obtained from a storage medium using a first read head; a second read channel to process a second input signal obtained from the storage medium using a second read head, which is offset from the first read head in each of two dimensions; a single digital timing loop configured to control interpolation of timing of sampling for first and second analog to digital converters in the first and second read channels; and a two dimensional equalizer coupled with output lines of the first and second read channels; the device being configured to account for a fractional timing difference between the first input signal and the second input signal, the fractional timing difference being a fractional amount of a single clock cycle of the device.

In one general embodiment, an apparatus includes a plurality of read transducers arranged in an array, and a plurality of biasing circuits. Each biasing circuit is coupled to a unique one of the read transducers. Each biasing circuit is configured to selectively reverse a direction of a read current applied to the read transducer associated therewith.

The embodiments of the invention improve the traditional disk drives by eliminating the mechanical actuator assembly that moves the read-write head attached to the actuator assembly, and replacing it with multiple read-write heads mounted over one or more rotating platters. The number of the read-write heads is preferably sufficiently large so that the read-write heads cover all tracks on the one or more rotating platters. In one embodiment, a disk includes a rotatable platter, a central spindle to rotate the rotatable platter arounds an axis, an electric motor to drive the central spindle, and multiple read-write heads mounted over the rotatable platter. In one embodiment, the platter includes multiple tracks arranged in form of concentric circles, where each of the read-write heads performs read-write operations on one of the tracks, and each track is assigned at least one of the multiple read-write heads.

The embodiments of the invention improve the traditional disk drives by eliminating the mechanical actuator assembly that moves the read-write head attached to the actuator assembly, and replacing it with multiple read-write heads mounted over one or more rotating platters. The number of the read-write heads is preferably sufficiently large so that the read-write heads cover all tracks on the one or more rotating platters. In one embodiment, a disk includes a rotatable platter, a central spindle to rotate the rotatable platter arounds an axis, an electric motor to drive the central spindle, and multiple read-write heads mounted over the rotatable platter. In one embodiment, the platter includes multiple tracks arranged in form of concentric circles, where each of the read-write heads performs read-write operations on one of the tracks, and each track is assigned at least one of the multiple read-write heads.

A magnetic processing unit (“MPU”) includes a magnetic element with one or more input channels and one or more output channels. The magnetic element can acquire magnetic arrangement configured to perform a predetermined operation on the received input signal and provide a resulting output signal.

A magnetic processing unit (“MPU”) includes a magnetic element with one or more input channels and one or more output channels. The magnetic element can acquire magnetic arrangement configured to perform a predetermined operation on the received input signal and provide a resulting output signal.

In one embodiment, a system for processing data includes a processor and logic integrated with and/or executable by the processor. The logic is configured to detect and track positive peak amplitudes and negative peak amplitudes of a readback waveform during data reading using a tracking threshold module, and to detect and track positive peak amplitudes and negative peak amplitudes of the readback waveform during the data reading at an input to an equalizer using a second tracking threshold module in response to reading a data set separator (DSS). Moreover, the logic is configured to perform asymmetry compensation on the data using an asymmetry compensator in an asymmetry compensation loop based on input from the tracking threshold module when not reading a DSS and based on input from the second tracking threshold module when reading a DSS, an output of the asymmetry compensator being provided to the equalizer.

According to one embodiment, there is provided a magnetic disk apparatus including an actuator, a shock detection circuit, a temperature measurement circuit, and a controller circuit. The actuator holds a magnetic head that accesses a magnetic disk. The shock detection circuit includes an acceleration sensor that detects acceleration during driving of the actuator. The temperature measurement circuit measures a temperature during driving of the actuator. The controller circuit changes sensitivity of the shock detection circuit according to a temperature change rate obtained from the measured temperature.

According to one embodiment, there is provided a magnetic disk apparatus including an actuator, a shock detection circuit, a temperature measurement circuit, and a controller circuit. The actuator holds a magnetic head that accesses a magnetic disk. The shock detection circuit includes an acceleration sensor that detects acceleration during driving of the actuator. The temperature measurement circuit measures a temperature during driving of the actuator. The controller circuit changes sensitivity of the shock detection circuit according to a temperature change rate obtained from the measured temperature.