Abstract: A disk drive is described with a single servo master timer that is used to control timing critical signals such as servo gate, SAM windows, channel power save, PREAMP power save and so on. The master timer is adjusted to compensate for SAM detection errors (early, late or missed) and provides improved servo timing quality. In an embodiment the adjustable master timer can be selectably clocked by either the DLC/DSW clock or the system clock.

Abstract: A disk drive is described with a single servo master timer that is used to control timing critical signals such as servo gate, SAM windows, channel power save, PREAMP power save and so on. The master timer is adjusted to compensate for SAM detection errors (early, late or missed) and provides improved servo timing quality. In an embodiment the adjustable master timer can be selectably clocked by either the DLC/DSW clock or the system clock.

Abstract: A method for screening a magnetic-recording head utilizing a simulated-cross-track-gain profile of the magnetic-recording head to provide a manufacturing-qualified, magnetic-recording head. The method includes measuring a track profile of the magnetic-recording head, and providing the simulated-cross-track-gain profile of the magnetic-recording head synthesized utilizing the track profile of the magnetic-recording head. The method also includes calculating a peak-to-peak value of the simulated-cross-track-gain profile, and applying a selection criterion based on the peak-to-peak value of the simulated-cross-track-gain profile to screen the magnetic-recording head for use as the manufacturing-qualified, magnetic-recording head.

Abstract: In an embodiment of the present invention, at least one mechanical fastener is used to mount a voice coil magnet assembly of a hard disk drive on a housing of the hard disk drive. A layer of a material having a low friction coefficient is disposed between the housing and the voice coil magnet assembly.

Abstract: A method for screening a magnetic-recording head utilizing a simulated-cross-track-gain profile of the magnetic-recording head to provide a manufacturing-qualified, magnetic-recording head. The method includes measuring a track profile of the magnetic-recording head, and providing the simulated-cross-track-gain profile of the magnetic-recording head synthesized utilizing the track profile of the magnetic-recording head. The method also includes calculating a peak-to-peak value of the simulated-cross-track-gain profile, and applying a selection criterion based on the peak-to-peak value of the simulated-cross-track-gain profile to screen the magnetic-recording head for use as the manufacturing-qualified, magnetic-recording head.

Abstract: In an embodiment of the present invention, at least one mechanical fastener is used to mount a voice coil magnet assembly of a hard disk drive on a housing of the hard disk drive. A layer of a material having a low friction coefficient is disposed between the housing and the voice coil magnet assembly.

Abstract: A HDD defragments itself while idle or in self-test when a defragmentation count exceeds a threshold. Also, the HDD combines G-list entries when a discontinuity count and a G-list entry density are both over a threshold.

Abstract: An Fe—Cr—Si based non-oriented electrical steel sheet contains 2.5% to 10% by mass of Si, 1.5% to 20% by mass of Cr, 0.006% by mass or less of C, 0.002% by mass or less of N, 0.005% by mass or less of S, 0.005% by mass or less of Ti, 0.005% by mass or less of Nb, and as necessary, 0.1% to 2% by mass of Al and at least one of 0.005% to 1% by mass of Sb and 0.005% to 1% by mass of Sn, and the balance being Fe and incidental impurities, wherein the electrical resistivity of the steel is 60 ??cm or more, and the number of nitrides containing chromium per mm2 in the interior of the steel sheet is 2,500 or less. Consequently, the problem that high electrical resistance resulting from the high Si content and high Cr content is not satisfactorily utilized is advantageously solved, and it is possible to provide a non-oriented electrical steel sheet having excellent magnetic properties in the high-frequency range, in particular, in a frequency range of 1 kHz or more.

Abstract: Components are provided including: an expected-value generating circuit that generates, upon reception of an output signal directed from the interface unit to the internal processing circuit; an expected-value signal for detecting an error in the output signal, a comparing and determining circuit that compares the output signal and the expected-value signal to determine whether these signals match with each other; and an output processing circuit that retains the determination result of the comparing and determining circuit and performs a process for externally outputting the determination result. In the case where a test pattern, which is an M-series pseudo-random-number signal, is input from a pulse generator or the like to the I/F unit for testing, a circuit based on a logic of generation of such an M-series pseudo-random-number signal is provided in the expected-value generating circuit.

Abstract: A HDD defragments itself while idle or in self-test when a defragmentation count exceeds a threshold. Also, the HDD combines G-list entries when a discontinuity count and a G-list entry density are both over a threshold.

Abstract: A method of changing the operating system in a computer system by using an address offset mode (AOM) feature for the address space of a hard disk drive connected to the computer system. Initialization of the computer loads the first operating system (OS) from a user area in the disk drive address space. An enable AOM command offsets the disk drive address space and reinitializes the computer to load a second OS from a reserve space in the disk drive address space. A command setting the maximum size of the address space of the hard disk drive provides a wrap around feature allowing the entire address space of the disk drive to be addressable for diagnostics or updating purposes. The computer is returned to operation with the first OS by a disable AOM command, or alternatively, by a power on reset, a software reset or a hardware reset. The method of changing operating systems is coded in the hard disk drive and does not require additions or modifications to the memory or the BIOS ROM of the computer system.

Abstract: A microwave amplifier includes a field effect transistor having its source grounded. The drain of the transistor is connected through a first inductor of gold wires to an output-side matching circuit, while the gate of the transistor is connected through a second inductor of gold wires to an input-side matching circuit. A series circuit including a capacitor and a third inductor is disposed near the input-side matching circuit and is connected between the junction of the input-side matching circuit and the second inductor and a reference potential.

Abstract: A microwave amplifier includes an amplifier, an impedance matching circuit for matching input and output impedances of the amplifier, and an open stub. The impedance matching circuit includes input and output side distributed constant lines each having a length equivalent to a 1/4 wavelength of a signal having the highest frequency in a desired frequency band. The open stub is disposed in the vicinity of the input or output side distributed constant line. The length of the open stub is varied to vary a narrow frequency band in which the maximum gain of the amplifier is attained. In this structure, the return loss is reduced and a uniform tuning in the frequency band is easily carried out using the open stub. In addition, the maximum potential of the amplifier is achieved in the desired frequency band.

Abstract: A microwave amplifier includes input-side and output-side matching circuits disposed on the input side and output side of a microwave FET. Each of the matching circuits is a distributed constant circuit including microstrip lines disposed on a substrate of dielectric material. The input-side matching circuit includes a connecting section for connection to the FET. The connecting section comprises a first microstrip line having a first width equal to that of the input-side matching circuit, and a second microstrip line continuous and integral with the first microstrip line and having a second width smaller than the first width. The connecting section connects the input-side matching circuit to the input of the FET.

Abstract: A high power field effect transistor (FET) amplifier which can provide a high gain over a wide bandwidth of a microwave range includes, on a first substrate on which a grounded-source field effect transistor is disposed, a series combination of an inductor and a capacitor connected between the gate of the FET and ground. The gate of the FET is coupled to an input impedance matching circuit disposed on a second substrate. The drain of the FET is coupled to an output impedance matching circuit disposed on a third substrate.

Abstract: A semiconductor laser device includes an n type first cladding layer and a multi quantum well active layer successively grown on an n type substrate, a p type second cladding layer having a stripe ridge narrower in the neighborhood of the laser cavity facets than within the laser disposed on the active layer, a p type buffer layer containing p type dopants in a higher concentration than in the second cladding layer and disposed on the second cladding layer except on the stripe ridge, an n type current blocking layer disposed on the buffer layer, and a p type contact layer disposed on an upper surface of the stripe ridge and the second cladding layer and the current blocking layer, the multi quantum well being disordered except directly opposite the wider portion of the stripe ridge by the diffusion of p type dopant impurities from the p type buffer layer.