Abstract: A process and a circuit control the rotational speed of a direct current motor. In particular, the motor may be used to drive magnetic or optical data carriers. The motor is fed with a motor current by a switching device for commutation wherein the motor current induces a magnetic flux which generates the motor torque. The process and circuit increase the motor voltage applied to the motor in the startup or braking phase to a value above the supply voltage. Further, the process and circuit reduce the motor voltage during the commutation phase so that commutation switching may occur in a reduced-current condition.

Abstract: A mounting for a semiconductor chip is composed substantially of polysilicon materials and incorporates integral heat dissipating elements into its design. The mounting can be cast from molten polysilicon or machined from a block of solid polysilicon depending on the shape and complexity of design of the mounting and heat dissipating elements. Polysilicon has excellent heat transfer properties and is closely matched to silicon in its coefficient of thermal expansion thereby reducing mechanical stress between the mounting and the chip. The semiconductor chip is attached directly to the polysilicon mounting establishing a direct thermal pathway between the heat generating chip and the heatsink elements of the mounting. The configuration of using direct attachment to a polysilicon mounting creates a thermally efficient package with greatly enhanced heat transfer capabilities and reduced mechanical stress. The mounting can accommodate both single and multi-chip applications in a variety of arrangements.

Abstract: An EMI shielding gasket made of springy electrically conductive material. The gasket includes a pair of generally parallel laterally spaced apart U-shaped channel members each with its channel entrance facing away from the other member. A pair of ends oriented transversely of the U-shaped channel members connect the members together at their end regions. The ends are resiliently deformable to allow the U-shaped channel members to be moved more closely together to facilitate mounting the gasket.

Abstract: A method and apparatus for a software actuable backup power controller for selectively controlling power to a volatile random access cache memory. If memory does not contain any data that needs to be retained during a primary power failure the controller isolates memory from the backup power supply during the power failure. Only when the memory contains data to be retained during a power failure will memory be treated as non-volatile and is the backup power supply connected to memory on primary power failure. By selectively enabling the backup power supply with software commands from the computer, a suitable cache memory can be constructed with a compact non-rechargeable battery.

Abstract: A low-profile magneto-optical media for double sided recording of information. The media comprises a single polycarbonate substrate having a relief in the form of tracking grooves or sampled-servo pits on each side surface thereof. Formed on each relief surface are thin-film active layers including a reflective layer, a transparent dielectric layer, a magneto-optical recording layer, and a transparent protective layer. The reflective layer is preferably formed of aluminum alloy. The dielectric layer is preferably formed of aluminum nitride or silicon nitride. The recording layer is formed of an amorphous vertically oriented magnetic material, preferably a rare-earth transition-metal alloy, for example, Tb-Fe-Co. The protective outer layer is formed of a transparent anti-corrosive material specifically compatibly with an air-bearing, low-flying, read/write head, preferably silicon nitride.

Abstract: A folder is described which holds and protects media, such as multiple disks, during and subsequent to shipping. An insert is provided that may be assembled with the folder and which increases the disk storage capacity of the folder assembly. A pocket is also provided to hold documentation associated with the disks.

Abstract: A method of forming a tachometer roller for a tape drive assembly for detecting the speed of a tape moving along a reference axis when the tape is in contact with the roller. The roller includes a cylinder extending in a longitudinal axis and adapted to be fixed in a tape drive assembly for rotation along the reference axis. The periphery of the cylinder defines an air vent groove running obliquely to the longitudinal axis for venting of air captured between the periphery and the tape. The vent groove terminates in respective circumferential grooves formed in respective edge portions of the roller. The vent groove is formed from a single plunge cut of a tool starting at a first circumferential groove and terminating at the other circumferential groove.

Abstract: An gasket is disclosed for environmentally sealing an enclosure of a disk storage device. The gasket, which is disposed between a base and cover portion of the enclosure is designed to accommodate a flat flexible wiring cable (flexcircuit) protruding therethrough.The gasket includes a compressible seal portion attached to the inner edge of a rigid plastic frame. The thickness of the seal is made slightly greater than the thickness of the frame. The width of the seal is substantially smaller than the width of the frame. A relief is formed on one surface of the gasket to receive the flexcircuit. The relief includes a groove extending across the width of the gasket. The groove has a depth essentially the same as the thickness of the flexcircuit, and a width slight larger than the width of the flexcircuit.Two ridges are formed across the entire width of the compressible seal portion of the gasket in the area immediately adjacent to the groove.

Abstract: Method and apparatus for supplying bias to a magnetoresistive element in an encapsulated thin film head for reducing the likelihood of generation of Barkhausen noise when reading flux from a magnetic storage disk. The invention achieves a relatively uniform easy axis bias field in an easy to implement manner by creating a magnetic bias structure on the encapsulated heat at the same time as providing the contact pads for the MR element.

Abstract: In a data processing system in which resource units are shared by a plurality of processing units, an arbitration unit is disclosed wherein the priority assigned to each processing unit is dynamically assigned to equalize accessibility to the shared resource. A signal path, associated with each possible level of priority, is coupled to each processor unit. The processor unit applies an activation signal to the signal line associated with the priority of the processing unit when the processing unit has a requirement for the shared resource and an arbitration is being performed to determine access to the resource. During the arbitration procedure, each processing unit requiring access to the shared resource compares the current priority of the associated processing unit to the activation signals on the signal paths to determine when the processing unit can gain access to the shared resource.

Abstract: In the manufacture of flat-panel video displays, an assembler must align long rows of closely-spaced electrical signal contacts on a planar electroluminescent panel with mating signal contacts on a flex circuit prior to clamping the panel and flex circuit together. The disclosed technique employs electrically conductive alignment contacts on both surfaces. The alignment contacts are formed via the same process that forms the signal contacts. The alignment contacts are connected to ohmmeters to form circuits that an assembler monitors to determine proper alignment of the surfaces. The use of electrical rather than visual alignment checking makes assembly easy and error-resistant.

Abstract: The disclosed invention relates to a video display system having a device for shielding electromagnetic radiation emitted from electrical wires which connect a video amplifier to a cathode ray tube. The device uses inexpensive unshielded wires which are recessed within a conductive shielding enclosure. The wires are connected to the cathode ray tube by a socket which is positioned at an access opening in the shielding enclosure. The invention further relates to a device for mounting a shielding enclosure to a base using tabs on the enclosure which are captured in an interference fit between the surface of the base and brackets coupled to the base.

Abstract: Methods and apparatus are provided for interconnecting first and second information buses each having a plurality of data lines. A pair of unidirectional information paths each consisting of twisted-pair cables are provided, along with a 25 MHz strobe. Information is transmitted using pseudo-ECL signal levels. A pair of clock differential receiver circuits is provided such that data is transferred over the interconnect bus using both the rising and falling edges of the transmitted clock signal and transferred from one bus to another at a rate of 50 MHz.

Abstract: A mounting block is disclosed which may be inserted and retained in a standard double-D aperture of a panel. The mounting block has a body which conforms in size and shape to the aperture and two ledges which provide ledge retaining surfaces. The mounting block also has two rectilinear notches in the body which expose notch surfaces which are in parallel spaced apart relationship with the ledge retention surfaces. The mounting block is inserted into the aperture and rotated 90 degrees of lock the mounting block in its retention position. In the retention position, the panel is captured between the ledge retention surfaces and the notch surfaces. Thus retained in the aperture, the mounting block is suitable for supporting loads or providing attachment points for screws or other fasteners.

Abstract: An isolation amplifier employs feedback to accurately amplify an input signal while maintaining electrical isolation between the input and output signals. The isolation amplifier consists of an amplitude modulator, an isolation transformer having a pair of matched secondary windings, a peak-detector output circuit, and a matching peak-detector feedback circuit. The isolation transformer couples an amplitude-modulated signal to both peak detector circuits while maintaining electrical isolation. The output from the feedback circuit is fed back to the amplitude modulator, so that the amplitude-modulated signal represents the difference between the input to the amplifier and the feedback signal.

Abstract: A hand held, one dimensional, torque feedback device is used to feel and manipulate computer generated visual information and associated torque forces. In the preferred embodiment, molecular bond data is manipulated in a virtual reality system. The device can also be used with a workstation generated display on a plurality of problems which generate torque.

Abstract: Printer apparatus provides a grayscale bitmap from a bitonal bitmap of desired output data. The apparatus includes a mapping function implemented as a lookup table for assigning predetermined grayscale values to bitonal bitmap pixels according to the neighborhood or subset of bitonal bitmap pixels including the subject pixel. From the grayscale values the laser of the laser printer is modulated to produce shades of gray during the printing of the desired data.

Abstract: This invention relates to a heat dissipation apparatus for cooling a number of heat generating electrical components mounted on a printed circuit board, some of which components are arranged in pairs, each pair being separated by a space. The apparatus includes two heatsinks positioned such that the parallel, thermally conductive walls of the heatsinks are adjacent to the heat transfer surfaces of the components. Disposed within the space separating a given component pair is a pressing fastener which has a yoke with a V-shaped recess into which is positioned a wedge. The positioning of the wedge in the recess is adjusted by means of a screw, resulting in the tines of the yoke spreading as the wedge is drawn within the recess. As the tines spread, they engage the paired components pressing them in contact with the heatsink walls.