Abstract: A change in an optical energy profile of energy emitted from a read/write head is determined. The read/write head includes an optical transmission path that emits the energy to heat a heat-assisted recording medium during writing. A change in optical efficiency of the read/write head is also determined. Based on the change in the optical energy profile and the change in the optical efficiency, a change in the effectiveness of the read/write head is determined, and in response a mitigation is performed.

Abstract: A maximum write duration is determined for first and second heat-assisted write transducers of a data storage device. Exceeding the duration results in thermal degradation of the first and second write transducers. A request to write data to a heat-assisted recording medium is received. In response to a time to fulfill the request exceeding the maximum write duration, the data is divided into portions such that a respective writing of each of the portions does not exceed the maximum write duration. Writing successive ones of the portions to the heat-assisted recording medium involves alternating between the first and second write transducers.

Abstract: A data storage device and associated methods may provide at least a data storage medium that is separated from a heat assisted magnetic recording data writer and is connected to a controller. The controller can be configured to change a laser power of the heat assisted magnetic recording data writer in response to a tested bit error rate of a median data track of a plurality of adjacent data tracks reaching an identified threshold.

Abstract: A maximum write duration is determined for first and second heat-assisted write transducers of a data storage device. Exceeding the duration results in thermal degradation of the first and second write transducers. A request to write data to a heat-assisted recording medium is received. In response to a time to fulfill the request exceeding the maximum write duration, the data is divided into portions such that a respective writing of each of the portions does not exceed the maximum write duration. Writing successive ones of the portions to the heat-assisted recording medium involves alternating between the first and second write transducers.

Abstract: An offset from track center of data is determined in a data storage device. The data is written to a heat-assisted magnetic recording medium of the device, and the offset compensates for degradation of an optical component of a read/write head when writing the data. The offset is stored in a memory of the storage device. Using the offset, a track alignment is changed during subsequent writes via the read/write head.

Abstract: A signal is recorded over at least part of a track a heat-assisted recording medium via a heat-assisted magnetic recording head. Symmetry of a cross-track profile of the recorded signal is determined, and the recording head is qualified based on the symmetry of the cross-track profile.

Abstract: During field operation of a heat-assisted magnetic recording data storage device, a laser adjustment procedure is repeatedly performed. The laser adjustment procedure involves writing, at a designated location on a recording medium at least three tracks at an unsqueezed pitch, a first track being in the middle of the at least three tracks. A first bit error rate of the first track is compared with a reference bit error rate. In response to the comparison satisfying a threshold, the laser current is swept while recording squeezed test tracks at the designated location to determine a new laser current that results in a minimum bit error rate. The new laser current is used for subsequent write operations.

Abstract: A data storage device and associated methods may provide at least a data storage medium that is separated from a heat assisted magnetic recording data writer and is connected to a controller. The controller can be configured to change a laser power of the heat assisted magnetic recording data writer in response to a tested bit error rate of a median data track of a plurality of adjacent data tracks reaching an identified threshold.

Abstract: A power level is applied to a laser that heats a heat-assisted recording medium is increased during recording for a plurality of iterations. Each iteration involves writing test data to a plurality of sequential tracks of the recording medium using the power level and determining bit error rates of the test data. Based on the bit error rates of the iterations, a power boost profile is determined. The power boost profile starts at a baseline level at a first track of a plurality of sequentially-written tracks, incrementally increases to a steady-state level over a first portion of the tracks, and remains at the steady-state level over subsequent ones of the tracks. The power boost profile is applied to the laser when recording to the recording medium.

Abstract: A system may have a data storage medium that contains at least one data bit that is accessed by a transducing head that has a near-field transducer. A controller can be connected to the transducing head and store a plurality of near-field transducer operating currents in a memory. The controller may identify a change in efficiency of the near-field transducer from the plurality of near-field transducer operating currents.

Abstract: A system may have a data storage medium that contains at least one data bit that is accessed by a transducing head that has a near-field transducer. A controller can be connected to the transducing head and store a plurality of near-field transducer operating currents in a memory. The controller may identify a change in efficiency of the near-field transducer from the plurality of near-field transducer operating currents.

Abstract: A pattern is written to only a portion of a test track of a magnetic disk. The pattern written to the portion of the test track is read using a read head. A cross-track offset between the read head and a write head is determined at a position on a disk based on reading the pattern.

Abstract: A method of bandwidth control and a corresponding bandwidth control device are disclosed, in which a plurality of queues are provided, bandwidth is assigned to each of the queues on the basis of a strict priority scheme, and additional bandwidth is assigned to the queues on the basis of a fair queuing scheme.

Abstract: A method of bandwidth control and a corresponding bandwidth control device are disclosed, in which a plurality of queues are provided, bandwidth is assigned to each of the queues on the basis of a strict priority scheme, and additional bandwidth is assigned to the queues on the basis of a fair queuing scheme.

Abstract: A circuit permits a user to present signals to control the flow of data from a first-type cell to a second-type cell. The circuit is susceptible to loading each cell individually, as well as loading cells by means of scanning input in a series through a low order cell to a higher order cell. The circuit may be copied as a series of cells wherein a bit held in each first-type cell is copied to the next higher second-type cell.

Abstract: A latch is described that provides soft error rate protection with integrated scan capability and collision avoidance. The latch has a latch output node and a first, second, and third sublatches. Each sublatch has a respective input circuitry, output node, and feedback circuitry coupled to the output node for reinforcing an output signal of the sublatch. Each sublatch is operable to receive a data signal at its input circuitry and responsively generate a binary-state output signal on its output nodes. The first and second output nodes such that, if an output of the third sublatch changes, the first and second sublatches force the third sublatch to have a same output. This “forced” change reduces the soft error rate in the latch and the output signal of the latch output node is restored without the sublatches colliding.

Abstract: A system and method of selective row energization based on write data, with a selective row energization system including a storage array 102 having M rows 104 and N columns 106; an N-bit data word register 108; a uniform-detect circuit 110 responsive to a data word to generate a uniform word data bit having a first value when the data word is uniform; an M-bit uniform-detect register 112 having M uniform-detect latches 114, each being associated with one of the M rows 104 and storing the uniform word data bit for the data word stored in the associated M row 104; and an M-bit row driver device 116 responsive to the uniform word data bit for each of the M rows 104 to inhibit energization of the M rows 104 for which the uniform word data bit is the first value.

Abstract: A method, system and apparatus for detecting soft errors in non-dataflow circuits. In a preferred embodiment, input is received at a latch system. The latch system consists of two pairs of latches. The second pair of latches is parallel to the first pair of latches. Both pairs of latches capture the input. However, the second pair of latches captures the input later in time relative to the first pair of latches latch. The captured input is then transferred from the first latch in each pair of latches to the second latch in each pair of latches. A comparison is made of the input in the two second latches. If the input captured in the two second latches is not the same, then a message is sent to a recovery unit.

Abstract: An apparatus and method are provided for reading a plurality of consecutive entries and writing a plurality of consecutive entries with only one read address and one write address using a 2Read/2Write register file. In one exemplary embodiment, a 64 entry register file array is partitioned into four sub-arrays. Each sub-array contains sixteen entries having one or more 2Read/2Write SRAM cells. The apparatus and method provide a mechanism to write the consecutive entries by only having a 4 to 16 decode of one address. In addition, the apparatus and method provide a mechanism for reading data from the register file array using a starting read word address and two read word lines generated based on the starting read word address. The two read word lines are used to access the two read ports of the entries in the sub-arrays.

Abstract: An apparatus and method for speeding up access time of a large register file with wrap capability are provided. With the apparatus and method, the 2:1 multiplexers in conventional register file systems are eliminated from the circuit configuration and instead, additional primary multiplexers are provided for half of the addresses, e.g., the first four sub-arrays of the register file for which the wrap capability is needed. These additional primary multiplexers receive the read address and a shifted read word line signal. The other primary multiplexer receives the read address and an unshifted read word line signal. The outputs from the shifted and non-shifted primary multiplexers are provided to a set of secondary multiplexers which multiplex bits from the outputs of the shifted and non-shifted primary multiplexers to generate the read addresses to be used by the multiple read/write register file system.