Abstract: A method of storing values that involves splitting each value into a n-bit value and an overflow value, and storing, in a main table, the n-bit values in order of increasing magnitude of the values. For each overflow value, the position of the smallest n-bit value is stored in an overflow table. To retrieve a value, the position of the corresponding n-bit value is compared to the positions stored in the overflow value to determine the overflow value of the n-bit value. The actual value is then obtained from the n-bit value and its overflow value.

Abstract: A method and apparatus for a settling check based on a single time point is described. A settling criterion for head oscillations in a disc drive is calculated using head position data. The settling criterion is used to determine when the head position data remains within a predetermined limit based on head position data values at a single point in time. The apparatus includes an actuator in a disc drive system including a head coupled to the actuator to generate a head position signal and a servo controller to receive the head position signal to determine when the head position signal remains within a threshold. The settling criterion could either be an elliptical settling criterion in one embodiment, or a triangular settling criterion in another embodiment.

Abstract: Audio or video information is stored as data files in clusters or blocks of sectors on a magnetic disc. The data files are transferred from the disc drive to one or more buffers for respective data streaming applications. Optimal buffer size is calculated using operational parameters such as transfer rates and rotational latencies. The sectors are grouped in blocks having a size equivalent to, or slightly larger than, the size of an associated host buffer for the respective application to avoid fragmentation of the data used in each buffer fill, and thereby minimize the time required to fill the buffer from the disc drive.

Abstract: A data handling system that effectively detects and diagnoses manifestations of excessive transducer instability. For example, some embodiments identify shouldering and baseline pop instabilities in a digital servo channel. A preferred method of the present invention involves detecting a precise time at which a first feature in the received signal is encountered. Then, after a preset delay, a first level of the received signal is sampled. Then, after waiting until after a second feature in the received signal occurs, a second level of the received signal is sampled. Finally, at least one digital signal is generated so as to indicate whether an arithmetic combination of the first and second levels falls outside a stability-indicative range. A preferred device of the present invention includes a transducer, a peak detector configured to receive a signal from the transducer, two delay elements, two sampling circuits, and an output.

Abstract: A data storage system achieves improved bandwidth efficiency using a modulated recording signal, channel linearization, and a compressor circuit for compressing peak amplitude of the recording signal. In a preferred embodiment, quadrature amplitude modulation and demodulation is utilized. Another embodiment achieves improved bandwidth efficiency using a recording medium having a substantially rectangular magnetic flux versus magnetic field intensity hysteresis characteristic and a substantially rectangular Kerr rotation versus magnetic field intensity hysteresis characteristic. Yet another embodiment achieves improved bandwidth efficiency using a storage medium having a substantially abrupt flux transition.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes an actuator assembly rotatably attached to said base and a device for moving the actuator assembly. The actuator assembly includes a transducer head in a transducing relationship with respect to the disc. The disc drive includes a disc drive controller for controlling movement of the actuator during track follow and track seek operations. The disc drive controller computes a phase difference time when a command is generated to complete a seek. When a seek is performed, the disc drive controller computes the phase difference time. Then the controller monitors the actual seek time, and adjusts the phase difference time based on a comparison of the actual seek time with the computed phase difference time.

Abstract: According to one embodiment of the present invention a method of operating a data network loop having at least two nodes includes monitoring deletions in an adaptive elasticity first-in, first-out (FIFO) buffer in each node, identifying each adaptive elasticity FIFO buffer that is a deleter, the deleter being an adaptive elasticity FIFO buffer for which information is deleted more often than information is inserted, and reducing a deletion threshold for each adaptive elasticity FIFO buffer that is a deleter. According to another embodiment of the present invention a buffer includes an adaptive elasticity FIFO buffer and a control circuit operatively configured to monitor deletions in the adaptive elasticity FIFO buffer, determine if the adaptive elasticity FIFO buffer is a deleter, and reduce a deletion threshold for the adaptive elasticity FIFO buffer if the adaptive elasticity FIFO buffer is a deleter.

Abstract: A method of pre-processing sampled data prior to estimating the peak amplitude of a pulse includes averaging of two adjacent sample values. Pre-processing makes the peak amplitude estimation less sensitive to the sampling phase relative to the peak position and consequently allows for the use of a lower sampling period relative to the full-width-half-maximum pulse width for a given peak estimation accuracy. The method incorporates a step in which a base line offset signal is subtracted from an estimated peak value, and multiplying the consequent pulse peak amplitude estimate by a predetermined constant in order to compensate for a systematic change in a final peak amplitude estimate. The multiplying constant may have a value derived from estimated peak values of other detected pulses in order to compensate for a systematic change in the peak amplitude estimate.

Abstract: A system for evaluating a head stack assembly used in an optical or optically assisted hard drive is provided. The system utilizes a reflective surface that is provided in a forward and return optical path that includes an optical head and associated optical components.

Abstract: A fiber-channel loop interface circuit that includes a dedicated transmit-frame buffer for loop initialization and responses (“responses” are non-data frames sent in response to commands or inquiries from other nodes). Having a dedicated transmit-frame buffer allows one port of a dual-port node to be transmitting initialization or response frames while another port is transmitting data frames, response frames, or initialization frames. Either or both ports can also be simultaneously receiving frames. The system includes a channel node having dual ports, each supporting a fiber-channel arbitrated-loop serial communications channel, and dedicated frame buffers within the channel node for loop initialization and responses. In some embodiments, the dedicated frame buffers are configured as on-chip buffers and include: two inbound non-data buffers coupled to the two ports, a data-frame buffer coupled to both ports, and an outbound transmit-frame buffer coupled to at least one of the ports.

Abstract: An apparatus and method for efficient defect management in a magneto-optical data storage system store a map of current and predicted defective physical addresses of a recording disk, and then skips defective data wedges to more completely utilize the non-defective recording surface area available for a given track. The invention also stores groups of physical addresses that share defects to decrease the number of entries in the map of defective physical addresses, and also to increase the effective defect management capacity of existing hardware and software.

Abstract: Data integrity is increased on mass-storage devices through a scheme whereby, a frame-based cyclic redundancy code (CRC) for each sector is recorded. A frame-based CRC is generated from the CRCs of the frames that compose a sector of data. In recording data, a CRC is generated from each frame, later, a master CRC is generated from the frame CRCs, then sector and master CRC are recorded on the mass-storage device medium. In retrieving data, the sector composed of frames and a master CRC are read, a plurality of CRCs are generated from each of the frames, a second master CRC is generated from the frame CRCs, and the master CRCs are compared to determine data integrity. In another embodiment, an input/output error detection and correction checksum (IOEDC), an error correction code (ECC) and a CRC are generated from a sector of data, and the IOEDC, ECC and CRC are stored on disc with the data sector.

Abstract: Information handling systems, disc drives, and methods for digitizing a readback waveform for testing a hard disc drive are disclosed. An information. handling system, such as a disc drive, includes a base, a disc stack rotatably attached to the base, and an actuator assembly movably attached to the base. Attached to one end of the actuator assembly is one or more transducers. Attached to the other end of the actuator is a voice coil that forms a portion of a voice coil motor. Magnets attached to the base form the other portion of the voice coil motor. An analog readback signal is reconstructed for use in testing a disc drive by digitizing a waveform generated within a read channel arrangement to produce digitized waveform data. The analog readback signal is then determined as a function of the digitized waveform data.

Abstract: A data storage communication channel includes a transmission medium, an initiator interface and a frequency selective multiplexer. The initiator interface includes first and second serial transmit ports. The frequency selective multiplexer includes first and second modulators and a circulator. The first and second modulators have first and second frequency bands and are coupled to the first and second serial transmit ports, respectively. The circulator is coupled between the first and second modulators and one end of the transmission medium.

Abstract: The present invention relates generally to the field of disc controllers, and more specifically to an efficient buffer manager for a disc controller. A state machine in the buffer manager is provided which is responsive to a clock controlled by a single frequency base clock signal and a speed selection signal which indicates the speed of the buffer memory and which is designed to provide a base clock signal for the state machine having a fixed base period and an extended second portion of the cycle period which is extended to reflect the time of the RAMs cycle, plus the necessary time to allow for circuit delays and the like. Thus, different speed RAMs can be used in association with the buffer manager designed in this manner, while always controlling access for reading and writing to the RAM during a single complete cycle of the buffer manager. This allows for direct gating of all control signals to the buffer RAM, simplifying the design of the buffer memory controller and its associated logic.

Abstract: The present invention provides sequence detection which takes into account amplitude and/or time distortions caused by neighboring magnetization regions on the magnetic medium, wherein the distortions in one magnetization region are caused by the closeness of neighboring magnetization transitions on one or both sides thereof. The sequence detection according to the present invention provides an extended state diagram to include the effects of leading and/or trailing magnetization transitions. More particularly, it has been found that accounting for the effects of trailing transitions requires an increase in the number of states in the state diagram used to form the Viterbi detector. Leading transitions are neutralized by increasing the number of branches between states in the Viterbi detector. Increasing the number of branches instead of states keeps the complexity low and thus saves hardware and associated costs.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes an actuator assembly rotatably attached to said base and a device for moving the actuator assembly. The disc drive includes servo circuitry and a controller for controlling movement of the actuator and head switches during track seek operations. The disc drive determines the average seek time for each head and also measures the amount of time for a head switch from the transducer head having the shortest average seek time to all the other transducing heads in the disc drive. When a seek is performed, the controller in the disc drive determines if the shortest average seek time plus the seek time from the transducing head to the transducing head on the surface containing the target track and sector is less than the average seek time of the head on the surface having the target track and sector.

Abstract: In a computer data storage system configured for patching Read Only Memory (ROM) by remapping data sections, the ROM containing a token to define the start of each one of the data sections and a patch existing for at least one of the data sections, the patch providing additional data at the start of the data section; whereby the patch is included in one of the data sections when an access to one of the data sections is initiated at the token. The patch further optionally replaces at least a part of one of the data sections. The patch may be in writeable memory and if so, the ROM appears writeable thereby. The indicator will normally be a software No Operation or non-destructive instructive, since a No Operation instruction (NOP) causes a one cycle pause in the processor and allows time for the patch to be smoothly integrated.

Abstract: A system and method is disclosed for correcting gain and offset errors in a signal amplifier for a position sensitive detector. The present invention eliminates the need to perform division for normalization by holding constant a signal proportional to the sum of the two signals generated by the position sensitive detector. First the two signals generated by the position sensitive detector are pulse-width modulated with a common variable duty cycle clock, and then the resulting modulated signals are low-pass filtered to extract the DC component. The duty cycle is varied so that the sum of the two DC components is held constant. In the preferred embodiment, the means for varying the duty cycle are closed-loop feedback and open-loop feed forward. The closed-loop feedback gives long term accuracy and the open-loop feed forward gives rapid settling time.

Abstract: A second order filter-delay element for use in a generalized analog transversal equalizer is described which provides phase and group delay responses equivalent to low-pass filters of third and fourth order. In addition, the filter-delay element provides sufficient values of delays required for proper operations of the analog generalized transversal equalizer despite having a low order. In addition, a method of generating the lower order filter-delay element is described. Also, a circuit embodying an active C-transconductor realization of a second order filter-delay element for use in a generalized analog transversal equalizer with a transfer function designed as a result of performing the method is described.