Abstract: Circuitry for distinguishing each value in a read signal magnetically recorded in ternary-3 position modulation in which the values 1, 2 and 0 are detected and equalized into a singlet, a doublet and absence of magnetic flux change. The circuitry first determines the position locations of each singlet peak and doublet crossover point to establish proper timing of the output signals and then identifies the particular type of signal appearing at the timing points in the read signal sequence. Singlets are identified by the much greater amplitudes in the integrated read signal. Doublets are identified as waveforms having slopes at zero crossovers that correspond in polarity to that of the previous singlet. A novel detector circuit is provided that can correctly identify doublets in a code sequence, irrespective of the presence of a previous singlet, when a recording rule is followed that includes the insertion of a number of consecutive ternary 0 symbols into the recorded signal.

Abstract: Apparatus for producing a circular-queue structure which permits interfacing between a high speed mini-computer and a relatively slow speed microprocessor via a common memory and with multi-device, asynchronous handling capability. The structure also permits commands and data to be chained in the same queue. The apparatus permits multiple devices to be handled simultaneously. By monitoring the memory address which is being accessed by the minicomputer, the information retrieved from the memory by the microprocessor is selectively validated or invalidated.

Abstract: A shell for a connector for flat shielded cable. The shell is formed of conductive material and is constructed so as physically and electrically to contact the shield so that grounding the shell will ground the shield. The shell also includes portions to grip firmly the cable so as to relieve strain from the cable-connector connection. Finally the shell defines a cavity for the connector; the cavity has one or more irregularities corresponding to mirror image irregularities in the connector cavity to assure proper positioning of the connector within the shell cavity. Associated with the receptacle adapted to receive the connector are two toggle latches; the shell is provided with external hooks adapted to cooperate with the toggle latches so as to achieve firm connection between the connector and the receptacle as well as connection of the shell to ground.

Abstract: A novel multilayer lift-off pattern of positive and negative photoresist materials is provided. A positive first layer is deposited on a substrate and flood exposed before a subsequent layer of negative photoresist material is added on top of the positive photoresist material. An optional third layer of positive photoresist material may be added on top of the negative photoresist to provide the top layer. A window or aperture is provided in the top layer employing conventional mask, exposure and development techniques. The top of the bottom layer is plasma etched through the window or aperture so that the previously flood exposed bottom layer can be developed without affecting the layers deposited thereon. A deep undercut lift-off pattern is provided which is useful in the manufacture of Josephson junction devices employing low temperature metals as well as for the manufacture of semiconductor devices.

Abstract: This invention is a device to reduce the wobble of a rotating shaft disposed in a cavity of a housing which wobble results from a spurious or undesirable positioning of a bearing assembly in which the shaft rotates. The present device includes a bearing follower which is shaped to have a long side which is in abutment with the side walls of the cavity. Accordingly, the follower cannot be readily placed in a cocked or misaligned position. The follower is spring loaded against the bearing assembly which is subject to being cocked and thereby reduces the capability of that bearing assembly to be misaligned.

Abstract: A unique memory management system for use with a memory device which is common (or shared) with a plurality of user elements utilizing a memory address counter, scratch pad address memory, external memory address inputs and an address multiplexer.

Abstract: A flexible moulded plastic panel closure is provided with a plurality of latches and retainers to permit the flexible moulded plastic panel to be attached through an aperture in a rigid wall of a chassis of a video display terminal. The flexible moulded plastic panel is provided with a plurality of resilient retaining fingers and tolerance springs for precisely mounting and holding an axial flow electric fan in a predetermined position to provide circulated air cooling for heat producing electronic components mounted inside of said rigid chassis.

Abstract: A video display terminal (VDT) is provided with a controller having six digital logic lines capable of defining sixty-four different colors. An eight color color display monitor (CDM) having three red, green and blue (RGB) video input lines is connected to a pulse width modulation converter capable of converting the sixty-four digital input conditions on the six low level voltage logic lines to sixty-four different color control conditions on the three video input lines.

Abstract: A relatively short broad band monopole coaxial antenna is provided with a center conductor and an outer radiator. The antenna is mounted above a ground plane and comprises a bare outer radiator portion adjacent the ground plane and a portion remote from the ground plane which is covered with a variable thickness microwave absorbent material. The signal to be transmitted is applied to the base of the monopole antenna adjacent the ground plane. Non-radiated signals propagate up the antenna. The high frequency components are absorbed by the microwave absorbing material. A tip matching network and a base matching network are coupled between the outer conductor and the ground plane for attenuating and matching the low frequency components of the non-radiated signals. The resulting monopole coaxial antenna has no undesirable reflections and has the appearance of infinite effective length antenna.

Abstract: An accurate radio frequency ranging system is provided for measuring the time required for a signal to be transmitted from a ground station to a remote station and to be returned to the ground station. The ground station is provided with a master reference clock that is employed to drive a first pseudonoise generator. The ranging system in the ground station is started by a unique and predetermined start epoch signal produced by the first pseudonoise generator. The first pseudonoise generated signals are transmitted to the remote station where they are tracked and sensed. When the original start epoch signal is sensed at the remote station, it is employed as a trigger or read signal to initiate the generation of a stop epoch signal. The stop epoch signal is retransmitted to the ground station and stored in a register where it is compared with pseudonoise generated signals being retransmitted from the remote station to the ground station.

Abstract: A superconductive Josephson junction high density memory array is provided. Each memory cell in the array comprises a two branch superconducting interferometer storage loop which has only a single Josephson junction device in one of the branches. The Josephson junction devices are mounted on a substrate having a patterned ground plane. The ground plane pattern is provided with holes or apertures which surround the Josephson junction devices so that the control current of the control lines couple with the tunnel junctions of the Josephson junction devices but not with the ground plane. This structural arrangement provides a threshold characteristic for the single Josephson junction device which is symmetrical to the gate current, thus, may be easily switched to two current states indicative of two logic states.

Abstract: There is shown and described a relatively simple electronic circuit using few discrete components which is used to replace the filter and delay line differentiator in existing circuits. The new circuit provides a simultaneous output of even and odd signals which have the same transfer function except for the derivative operation. The circuit is especially useful in read and write channels of a disk drive apparatus.

Abstract: Apparatus and method for encoding binary data in a ternary format including ternary 0, ternary 1 and ternary 2 code symbols. In a preferred embodiment of the invention utilized for magnetic data storage, a ternary 0 is represented by the absence of signal change, a ternary 1 is represented by a single transition and a ternary 2 is represented by a pulse or pair of closely spaced transitions. Further features of the invention provide for merging ternary code symbols so as to prevent the spacing between adjacent symbols from becoming so small as to create undesirable crowding, and inserting and shifting symbols to prevent the spacing between adjacent symbols from becoming so great as to adversely affect recovery of the encoded data.

Abstract: A Josephson junction latch circuit is provided which has an AND gate having plural inputs and a single output. The output of the single AND gate is directly coupled to a Josephson junction flux storage loop capable of storing flux indicative of the output of the AND gate. A Josephson junction sense line is provided capable of sensing the flux condition of the flux storage loop. The sense line is directly coupled to amplifying gates which produce amplified true and complement quantities whenever the sense line is actuated.

Abstract: A dehumidifier for a head-disk assembly in a disk drive unit. The dehumidifier includes a housing which is ported to define an air passage therethrough. Within the passage is a Peltier effect device that has a cold surface exposed to air flowing within the passage and a hot surface connected to a heat radiator. Water vapor carried in air that contacts the cold surface condenses; there is sump below the cold surface to contain water that condenses. The housing is installed so that air flow through the passage is induced by convection.

Abstract: A wafer holding chuck for a wafer sectioning machine is provided with a substantially flat chuck plate having an extremely flat resilient strip support for supporting only a very small area of the wafer above the surface of the chuck plate at a point opposite the rotating abrasive tool. The pressure of the highly accurate rotating abrasive tool engages the front surface of the wafer to be sectioned and the resilient strip support conforms to the rear surface of the wafer causing the abrasive tool to make uniform contact with the front surface of the wafer being sectioned so that the section cut in the wafer is extremely uniform.

Abstract: An improved high speed gallium arsenide (GaAs) to emitter coupled logic (ECL) voltage level converter is provided which consumes less power and also provides an improved speed-power product performance characteristic. The converter includes a three branch output circuit which emulates the operation of an ECL output driver. The emulator circuit causes faster switching by compensating for parasitic resistances and capacitance and is also provided with a gate discharge network which reduces switching time of the ECL output emulator.

Abstract: During the preparation of a Josephson junction device, one of the steps for making a base electrode is to deposit a superconducting material on a substrate and to anneal the deposited material to make it a continuous homogeneous polycrystalline grain-like electrode material. Ordinarily, the base electrode and the counter electrode materials are deposited in a vacuum system at a vacuum pressure which is below one.times.10.sup.-6 torr to remove all contaminants such as oxygen, oxides of carbon and water vapor. It has been discovered that depositing conventional superconducting base electrode and counter electrode materials in the presence of an inert gas at much high vacuum pressures around 20.times.10-3 torr produce a superior lead-gold superconductive electrode which is substantially immune to thermal cycling.

Abstract: There is shown and described a high speed bus architecture which uses a common control bus and permits high speed data transfer between a plurality of active and/or passive users while reducing the system overhead structure which was previously required.

Abstract: A gallium arsenide buffer amplifier for use in a very large scale integrated circuits is provided. The transistor device in the buffer amplifier has a uniform depth N+ source, gate and drain region and the N+ dopant concentration is made very high which effectively reduces the resistance of the transistor device and permits the area of the device to be reduced by more than one order of magnitude while maintaining high current and power levels.