Abstract: An apparatus comprises: an array of coupled quantum elements in a housing configured to provide a low-temperature environment, where one of the quantum elements comprises: a first fluxonium qubit circuit (FQC), and a qubit coupling circuit configured to couple the first FQC to a second FQC; and a control module configured to apply magnetic flux pulses to quantum elements in the array of coupled quantum elements based at least in part on signals received from a digital signal interface providing digital control signals into the housing, the control module comprising: a DAC module that comprises one or more SFQ circuits that receive a digital input and generate the magnetic flux pulses, and a control coupling circuit configured to provide mutual inductive coupling between at least one of the SFQ circuits and at least one of the first FQC, the second FQC, or the qubit coupling circuit.

Abstract: A network storage device having a network controller card and a data storage device is described herein the card and storage device are either enclosed in a small from factor unit or assembled together to fit within a standard hard disk drive bay in a computer. The combination of a controller card and storage device is designed to transfer files from and to a network using standard network file protocols. As the network storage device does not process the files, much of the computational overhead of a network server can be eliminated, resulting in a simpler device capable of faster file exchange.

Abstract: The sensing assembly comprises a microprocessor, a cam, and a position sensor that provide feedback on the disconnection status of a buckle between a takeup leader and a tape cartridge leader. The microprocessor uses the position sensor to detect a first position and a second position of the takeup leader in the tape path. The microprocessor uses the movement between the first position and the second position to determine if the takeup leader and the tape cartridge leader are disconnected prior to ejecting the tape cartridge. The cam permits the load motor operation to be briefly paused during the sensing.

Abstract: A method for detecting slippage in a tape path, and re-calibrating a sensing assembly in a tape storage device to account for the slippage. The method includes sensing a position of one of a supply reel and a take-up reel. In response to sensing the position of the supply reel or take-up reel, sensing a position of a guide roller. The position of the guide roller corresponds to the position of the guide roller when the position of the supply reel or the take-up reel is sensed. In response to sensing the position of the guide roller, the tape media is wound through the tape path between the supply reel and the take-up reel. In response to winding the tape media through the tape path, a second position of the one of the supply reel and the take-up reel is sensed. In response to sensing the second position of the one of the supply reel and the take-up reel, a second position of the guide roller is sensed.

Abstract: An improved magnetic read/write head actuator assembly for use within a storage disk system that provides reduced average access time. The actuator assembly includes an actuator arm mounted on a pivotal E-block structure. A read/write head is supported at a distal end of the actuator arm such that the head is positioned in close proximity to a rotating magnetic storage disk. An actuator motor cooperates with the E-block structure to provide pivotal motion to the actuator arm about a central pivot axis. The actuator motor includes a pair of rotor windings connected to the E-block structure at an end opposite the actuator arm and stator magnet structure that is statically mounted in close proximity to the rotor windings. The actuator motor further includes a flux conductive member for forming a closed magnetic flux path through the windings and the stator magnets. The pair of rotor winding are oriented in a plane normal to the plane defined by the pivotal angular motion of the actuator assembly.

Abstract: A method of data transfer in a cache system comprising a cache buffer including a plurality of data blocks for storing data, and a cache manager for retrieving data from a disk drive and storing the data into the cache buffer. The disk drive includes a data disk having a plurality of concentric data tracks thereon, a spindle motor for rotating the data disk, and a transducer supported by a carrier for positioning the transducer over individual data tracks to write data thereto or read data therefrom.

Abstract: A methodology for designing and implementing high rate RLL codes is optimized for application to 8-bit ECC symbols, and provides modulation code rates including rate 32/33; rate 48/49; rate 56/57; rate 72/73; rate 80/81 and other code rates for use in magnetic recording channels. A relatively small subcode encoding—one easy to implement—is applied to a portion of the input stream, and the resulting base codeword is partitioned into nibbles that, in turn, are interleaved among the unencoded ECC symbols. Code constraints on the subcode word nibbles depend upon the values of adjacent unencoded symbols. The resulting codes provide excellent density and error propagation performance.

Abstract: A system for producing a quotient B/A, where A and B are elements of GF(22M), 2M+1 is prime and 2 is a primitive element of GF(2M+1), first determines A−1 and then multiplies B by A−1. The system uses a (2M+1)-bit representation for A and produces, directly from A, an element C=A2M+1, where C also is an element of GF(22M) which is a subfield of GF(2M). The system produces M+1 bits to represent C by performing bit manipulations that are equivalent to permuting the (2M+1)-bits to produce A2M and multiplying the permuted bits by A. The bit manipulations are: c0=&Sgr;aiai; c1=&Sgr;aiai+1 . . . cM=&Sgr;aiai+M where the aj's and cj's are the coefficients of A and C, respectively. The system retrieves C−1 from a (2M−1)-element lookup table and multiplies C−1=A−2M+1 by A2M to produce A−1.

Abstract: In a data processing system comprising a host system and a memory device including a data storage medium of a predetermined size and corresponding capacity, a secure method of managing available capacity of the storage medium by: maintaining an authentication list comprising a plurality of entries including information uniquely identifying a plurality of memory devices; selecting a section of said data storage medium for data storage, said section having a size representing the available capacity of the memory device; and maintaining identification information in the memory device uniquely identifying the memory device.

Abstract: A timing error extractor (166) determines the phase angle between an input signal and a sampling clock by computing arctan(v/u)=arctan(alog(log(v)−log(u)), where (v) and (u) are the respective quadrature amplitudes of the input signal and sampling clock. The log function values are stored in a first lookup table (180) that is time-shared by a switching function (182) to provide both log(v) and log(u) values. A storage element (184) holds the log(u) value while the switching function routes magnitude (v) to the first lookup table. The resulting log(v) value and the stored log(u) are combined in a subtraction function (186) that generates log(v)−log(u), which result addresses a second lookup table (188) that returns the addressed arctan(alog(log(v)−log(u)) value. This phase estimating approach is advantageous because it is gain insensitive, does not include a costly and time-consuming divide operation, and requires a relatively small lookup table.

Abstract: A method of controlling a disk drive that reduces the space on the data storage surface of a storage disk otherwise effectively required to be taken up by embedded servo sectors. In disk drives employing wide-writer, narrow-reader, dual element heads, each servo burst field ends with a burst correction value (BCV) field. This BCV field enables the wide-writer head to be accurately positioned within track boundaries before writing begins to the data sector following a servo sector. The present invention takes advantage of the fact that burst correction values are only required by the head incident to data writing operations. Since a finite settle time is required to switch the read channel from servo mode to user data mode, and since the BCV field is not needed for reading operations, mode switching and channel settling can begin while the head is still passing over the BCV field.

Abstract: A magnetic tape cartridge having an integral key is provided for use within a magnetic tape drive having a tape cartridge guide assembly adapted for use with the integral key. The integral key is defined on the exterior of the cartridge housing and comprises a raised fixture or tab. The tape cartridge guide assembly includes at least one slit portion. During use, the tape cartridge having the integral key is inserted into the tape drive, the integral key is aligned and permitted to traverse the slit portion for enabling the cartridge to enter the subsystem.

Abstract: Methods and apparatus for reducing electrostatic discharge damage to a read/write (R/W) head attached to a shutter/head assembly are disclosed. In accordance with one aspect of the present invention, a shutter/head assembly includes a lead screw, a head housing, and a shutter. The head assembly is configured to be coupled to a R/W head, and is rotatably coupled with the lead screw. The shutter is also rotatably coupled to the lead screw, but in such a manner that the shutter is able to rotate independently of the head housing. The shutter is also configured in such a manner so that it rotates to a radial position between the R/W head and the tape/leader ribbon when the lead screw brings the shutter toward a certain linear position, and rotates to another radial position away from the R/W head and the tape/leader ribbon when the lead screw brings the shutter toward a different linear position.

Abstract: A pulse-width-modulated digital-to-analog converter is responsive to a digital control value for switching between a high gain mode and a low gain mode. The converter includes a free-running rollover counter, a reference register and a comparator. Pulses from a comparator are split into two paths, one path including a switch, and fed into a plurality of resistive elements connected connected to a common output node. Depending on the state of the switch, the network's output value will either follow its input or be a fraction thereof, without change of duty cycle or output impedance. The output node may be connected to a capacitive element to form a low pass filter for generating an analog waveform.

Abstract: A method and arrangement for preventing the locking out of devices which are coupled to a bus by either of two of the devices which have become initiator and target devices respectively. The devices arbitrate for control of the bus after the bus enters a bus free phase. The device which wins the arbitration becomes an initiator. A timer in each device on the bus is started upon the initiation of arbitration. The initiator device is removed from the bus when an elapsed time after the timers have been started reaches a predetermined value. The distributed clock of the invention ensures that the devices coupled to the bus will clear the bus after the initiator has been on the bus for a pre-determined time, thereby obviating skew problems associated with single clocked systems.

Abstract: A phase locked loop has an average zero phase start circuit to detect and correct for the average phase difference between a data signal and a VCO clock signal over a short interval at the beginning of phase-lock acquisition. The average zero phase start circuit has a data comparator to split the data stream into odd and even portions; odd and even pulse position detectors to detect the phase difference between pulses of the odd and even data signals and corresponding pulses of the VCO clock; and a ramp generator to generate a voltage corresponding to the sum of the detected phase differences. The ramp generator employs a capacitor and switched current sources that discharge the capacitor at a fixed rate to generate the voltage. After 4 phase difference measurements are taken, the VCO is stopped, and another current source discharges the capacitor at 4 times the fixed rate.

Abstract: An actuator assembly latching apparatus for a disk drive is realized with an elongated flexible vane disposed in proximity to a rotating disk. The rotating disk produces an airflow at different speeds across the flexible vane. Resulting differential ambient air pressures produce a net force which deflects the vane toward the disk surface thereby to unlatch a head arm actuator assembly within the disk drive. Once disk rotation ceases, the vane returns to its original, undeflected position and latches the head arm actuator assembly to maintain heads at a radially innermost parking location on the disk surfaces.

Abstract: A spindle and hub assembly in a disk drive having an integrated motor including a housing having a cylindrical sleeve and two end flanges, the cylindrical sleeve and the upper end flange being one piece and forming the hub and the lower end flange being pressed into the hub and a shaft being rotatably supported in the end flanges by means of hydrodynamic bearings, where the hydrodynamic bearings have conical bearing surfaces converging towards the interior of the housing, whereby a high precision and low cost spindle and hub assembly is provided.

Abstract: A method and system for verifying the integrity of data written to a mass memory medium. A local memory is directed by local memory control logic to store a data block that is received from a host microprocessor and that is to be written to the mass memory medium. The data block comprises a sequence of data symbols. An ECC encoder encodes the stored data block with error correction data. The error correction data comprises a sequence of error correction symbols that are appended to the data symbols. The data and error correction symbols are stored in the mass memory and immediately retrieved. An ECC decoder receives the retrieved data and error correction symbols from the mass memory and the data and error correction symbols of the encoded data block from the encoder. In response, the decoder generates an error status signal when more than a predetermined threshold number of the retrieved data and error correction symbols are improperly stored in the mass memory.

Abstract: A magnetic head and its manufacture where the head includes two spaced apart coplanar wear surfaces that are aligned along an axis in spaced apart relationship. Nonmagnetic material joins the two raised wear surfaces. A transducer is imbedded in the nonmagnetic material. And the transducer has an elongated surface of uniform width on one side that extends in a direction transverse to the raised wear surfaces. The elongated surface of the core and the surface of the magnetic material together form a composite wear surface that is generally coplanar with the raised wear surfaces. The area of the elongated surface of the magnetic core and the surface area of the nonmagnetic material are so proportioned that the wear of the composite wear surface is controlled by the nonmagnetic material.