Abstract: A large scale integrated circuit is designed to handle bus-to-bus data and address transfers, manipulation, and temporary storage. A key feature of the device is that it generates error correcting code parity bits on a byte wide basis so that ECC check bits for a multi-byte word can be generated externally with a minimum of hardware, and includes circuitry responsive to an error syndrome for correcting a single error within a byte. Data manipulation capabilities include standard logical operations, single bit shift operations, binary 2's complement arithmetic addition and subtraction, and decimal addition and subtraction. In addition, an input data byte on any bus can be passed unaltered or inverted to any other bus. The device is capable of receiving operands from one or two of three bidirectional data buses, performing a desired arithmetic or logical operation on the operand or operands, and returning the result to any one of the bidirectional buses including one which may have supplied one of the operands.

Abstract: A modular bus system for reporting the status of a plurality of geographically distributed data points. The data points may be independently located or grouped with the status of each being monitored by a processor which is coupled to the data points via a bus multiplexer, a plurality of buses and a plurality of single point and multiplexed transmitters. Each bus may be coupled to a plurality of the transmitters and may be configured open or closed loop. The system operates to simultaneously interrogate each of the buses via interrogation signals, which also supply the power to the transmitters, and produces a serial response signal containing the status information of the interrogated data points.

Abstract: A mechanism is provided which permits the insertion of elements into a list of positions determined by the rank of the elements and allows deletion of elements only from the top of the list. The arrangement provides dynamic aging of the priorities of the elements entered into the list.

Abstract: The present invention provides a spread spectrum waveform encoded altimeter. Spread spectrum carrier wave signals which are transmitted and later received are processed in a novel edge detecting apparatus which includes a plurality of individual detectors. A pair of detectors are provided to detect an early chip or signal. Another pair of detectors are provided to detect a late chip or signal. There is also provided a pair of edge chip detectors for detecting the center or locked on chip signal. Logic circuits are employed to sum the voltage signals from the detectors and to provide a control signal capable of adjusting a tracking generator to enable it to lock on to the received signal. An altimeter counter is provided which is started by a unique chip in the transmitted signal and stopped when the same unique chip is detected in the receiving and tracking loop.

Abstract: A memory array having a dedicated refresh flag memory (RFM) for maintaining a record of the array's addresses that are accessed during a refresh requirement interval (RRI) and means for reading the RFM during the RRI and refreshing those array addresses which weren't accessed during the operating interval of the RRI. The refresh operation being performed in a "burst" mode or in an "interleaved" mode during the RRI.

Abstract: An accurate radio frequency ranging system is provided for measuring the time of transmission of a signal from a first station to a second station and back to the first station without coherent turn-around of the signal. Each of the two stations is provided with its own range measuring means and its own reference clock. The first station range measuring device is started by the first station reference marker and is stopped by the second station reference marker start signal transmitted from the second station to provide a first range measurement. The second station range measuring device is started by the second station reference marker and is stopped by the reference marker start signal transmitted from the first station to provide a second range measurement.

Abstract: Apparatus for checking the correct operation of a parallel byte shifter of the type having a plurality of input ports connected to individual byte lines of a data bus. When predetermined byte lines to the byte shifters are selected, control means are provided to activate a set of shift select means connected to error checking circuits. The error checking circuits comprise logic gating means for checking the proper selection of byte lines and for storing a signal indicative of an error or absence of an input error in the error storage means. When the data byte is being transferred out or read out of the byte shifter, the error storage means is read out to determine the presence or absence of an output error from the error storage means.

Abstract: A duplexing apparatus for printing data or information on both sides of a sheet of paper to be used with laser printers or paper copiers is disclosed. Sheets of paper are fed from a paper feeding station for presentation to an image transfer station. The image transfer station transfers toned images, present on a photosensitive member, to the sheet of paper. After the transfer, the paper is moved along a discharge path to a duplex device which is disposed in close proximity to the paper feeding station. The duplex device engages the sheet of paper leaving the transfer station and either discharges the paper if printing is done thereon to a discharge station or returns the sheet of paper to the paper feeding station for a second presentation to the transfer station for duplex printing. Coded pagination information is sensed and sent to a microcontroller which checks the data to confirm that the pages of data on each of the sheets are being printed in the proper order.

Abstract: A steerable directional antenna assembly steerable about two perpendicular axes is disclosed. It comprises a directional horn antenna rotatably mounted on a horseshoe gimbal to rotate about a first axis. A curved wave guide feed is connected at one end to the feed portion of the directional antenna. The wave guide feed is disposed such that its center of curvature is located on the first axis of rotation. The curved wave guide has a circumferential slot in its outer side, the slot communicating between the ambient atmosphere and the wave guide interior. The gimbal and directional antenna are rotatably connected to a pedestal which is enabled to rotate the gimbal and directional antenna about a second axis which is perpendicular to the first axis. The antenna assembly further comprises a coaxial feed line which passes through an opening in the pedestal and is fixed to the pedestal. The outer conductor of the coaxial feed line is stripped away from one end of the line to expose the center conductor.

Abstract: A character overprinting apparatus and method for overprinting in a laser non-impact printer is disclosed. Control bits are generated and assigned to data words transmitted from a host system. An underline control bit identifies whether the associated data word will require underlining and a data control bit identifies the data word as a character space or a character shape. An intermediate storage register stores a line of data words and associated control bits for overprinting. Stored data words and associated control bits from the intermediate storage register and data words and associated control bits from the host system are compared in an overprinting circuitry means to effect a selected merger of the data words and a selected modification of the control bits. The merger and modification are done in accordance with a pre-selected set of overprint rules.

Abstract: A method and apparatus for growing liquid phase epitaxial (LPE) crystals upon only one surface of a supporting substrate. The method requiring the insertion of a gasket between a pair of substrates, upon whose exposed surfaces it is desired to grow an LPE crystal. The gasket essentially acting to contain a meniscus of entrapped flux and thereby entrap an air bubble between the substrates so as to prevent growth upon the interior surfaces of the assembly.

Abstract: Proportional spacing of characters, for example by a laser-xerographic printer, is achieved using a character generator memory, for example a random access memory (RAM), to store the characters of a font in a plurality of variable-size binary matrices. Each column includes at least one parity bit and at least two pitch bits or end of character (EOC) bits. After a character matrix is selected for printing: the columns are transmitted sequentially from the RAM, the bit patterns are decoded as valid and invalid EOC indication signals or as valid and invalid NON-EOC signals, and the parity of each column is checked. Also, stop printing circuitry inhibits operation of the dot matrix printer when the parity checker indicates no error but the pitch bit decoder derives an invalid EOC or NON-EOC SIGNAL.

Abstract: An apparatus for and a method of providing an amplified, directable laser light beam is disclosed. The apparatus includes two optical cavities sharing a common mirror. The first cavity is resonant and contains a laser rod intermediate a high reflectivity reflecting mirror of 100% reflectivity and a low reflectivity transmitting mirror of 10-90% reflectivity. The second cavity is antiresonant and contains a Faraday effect diffraction grating intermediate the low reflectivity mirror and a 100% reflectivity mirror. The laser light beam that passes through the transmitting mirror is directed normally incident to the surface of and passes through the Faraday effect diffraction grating. On the far side of the diffraction grating is a mirror of 100% reflectivity, which reflects the laser light beam back through the diffraction grating forming a pair of diffracted congruent 1'st order light beams and a single undiffracted 0'th order light beam.

Abstract: A duplex copying machine having a simple and automatic method and apparatus for handling paper at a duplex feeding station in a duplex copier is disclosed. A container for holding a stack of paper is removably connected to the duplex copier at a paper feeding station. The stack of paper is aligned and partially confined within the container by vertically extending surfaces which align the edges of the paper sheets within the stack. Top portions connected to the vertical surfaces extend horizontally over a portion of the top sheet of the stack. The stack of paper rests on an intermediate support plate within a container which is biased against the top portions. Extension members connected to opposite sides of the intermediate support plate are disposed to move within slots in opposite sides of the container. A pair of solenoids are connected to contact members and fixed to the duplex copier. When the container is mounted on the duplex copier the contact members come in close proximity to the extension members.

Abstract: A spread spectrum carrier wave device, such as an altimeter, is provided having a transmitting antenna in close proximity to the receiving antenna. The reference signals being transmitted are electromagnetically coupled into the receiving system as undesirable signals. When the strength of the undesirable signals becomes stronger than the desired signals, they mask the desired signals and make them difficult to recover. The undesirable signals are removed from the receiving path by generating a replica of the undesired signals and applying them to an input of an adaptive processor with the signals in the receiving path. After the undesired signals are removed by the process of adaptive nulling, the desirable signals are recovered and processed.

Abstract: A binary data encoding and recovery technique for which the encoding is carried out by separating the binary data into successive data words each containing an equivalent number of data bits, generating one or more code signals representative of each data word where each code signal corresponds to a signal change at one of a plurality of signal change positions in a data cell associated with the data word and is spaced from adjacent signal changes in the data cell by at least a prescribed minimum amount, and assuring that succeeding signal changes occurring in a sequence of data cells are spaced at least the prescribed minimum amount by determining whether a signal change in one data cell would be spaced less than the prescribed minimum amount from a signal change in an adjacent data cell and in such event providing for the code signals related to such signal changes to be merged into a code signal corresponding to a signal change positioned at the boundary of the adjacent data cells so that the prescribed mi

Abstract: A system for compensating misalignment between information represented by transitions in a data bearing medium and a played back signal, the played back signal having consecutive opposite-polarity peaks corresponding to said data transitions, which system comprises a low-pass filter, which receives a signal from a non-linear element, preferably a pulse forming circuit, into which has been introduced the misaligned played back signal, and circuitry for converting the filtered signal to a series of pulses representative of the data transitions, which pulses have reduced misalignment with respect to the data transitions.

Abstract: The present invention relates to apparatus for printing graphic forms simultaneously with information data. A graphic forms master is mounted on a relatively small forms drum which is coupled to rotate simultaneously with a photo-sensitive print drum. Light is reflected from the graphic forms master to a light sensitive transducer from where electrical signals, representing the graphics form, are transmitted to a signals merging circuit. Information data signals are also transmitted to the signals merging circuit. The signals merging circuit is connected to a single light source-optical system to selectively pass light to the photo-sensitive print drum in response to the electrical signals to provide an image thereon representing both the graphic form and the information data. Automatic lateral alignment of the graphic forms data and information data is accomplished through cooperation of an alignment mark on the graphic forms master with a portion of the signals merging circuit.

Abstract: A magnetic bubble replication and transfer arrangement is disclosed which provides for replicating magnetic bubbles in thin planar layers of magnetic material without the need for electrical current carrying conductor elements. The arrangement includes a replicating half-disc permalloy element disposed in a particular way between first and second tracks formed from half-disc elements which are deposited on a surface of the magnetic layer. When a rotating magnetic field in the plane of the material is rotated in a predetermined direction with respect to the above arrangement, replication of a bubble in the first track occurs at a replication region where a portion of the replicating element is adjacent the first track. The original bubble continues movement within the first track while the newly formed bubble moves along the replicating element into the second track in response to rotation of the in-plane magnetic field.

Abstract: A crossed light beam position indicator includes orthogonal arrays of paired light emitters and detectors for covering a display surface with crossed light beams and scanning means coupled to the emitters and detectors for electronically scanning the orthogonal arrays such that a single emitter at any one time is emitting light. Improved initialization means detect the first occurrence of an interrupted light beam and in response to the first detection, reset the scanning means to the initial reset position to thus avoid transmitting an address that might represent only the edge of an object placed in proximity to the display screen and caught by the scan only after the scan had passed the position occupied by the main body of the object.