Abstract: A method for performing inter-processor communications in a multiprocessor system combines the sending of a message with the sending of a message interrupt. Messages are exchanged through a shared memory organized into pages, each of which may be "owned" by a processor. When a sending processor executes a store instruction that stores its operand to a memory area owned by a destination processor, a message interrupt is presented to the destination processor. If the destination processor is interrupt enabled, the operand of the store instruction is stored at the address specified by the store instruction and that address is stored in a register of the destination processor. Execution of the store instruction by the sending processor then completes.

Abstract: A circuit for converting RGB to composite video. The circuit is particularly useful in a video overlay application. Notch filters are used both in the video path and keying path. The notch filters are centered at frequenices equal to the dot clock frequency of the RGB divided by integers where the result of this division falls within the chroma subcarrier spectrum.

Abstract: The subject invention is an optical sensor detection system for a serial printer useful for the determination of alignment and misalignment of images on a sheet of print media and the correction of misalignment. The present invention includes a photoelectric sensor mounted on the carriage of a serial type printer to locate various indicator markings.In operation the sensor detects the position of a midpoint indicator when the carriage travels from right to left, and then from left to right. The positional information is then compared with the assumed mid-carriage position of the print head based upon the time of travel, that is, the predicted position of the sensor assuming no flex in the support members of the print head and no stretch of the belt driving the print head.

Abstract: A circuit for allowing a clock of any specified duty cycle to be created from a clock of the same frequency using standard digital delay lines. In particular, an EXOR function is implemented to generate a clock signal having a frequency which is twice the frequency of its input signals by using standard logic components such that the active branch for each input edge has an independent path to the output signal. In this manner, if a time delay is introduced into the active branch and only the active branch, the corresponding output edge and only that edge will be delayed by a like amount. Over a complete cycle of the input waveforms, four output edges are produced (two clock cycles). By varying the delay on the input branches, these output edges can be placed independently and arbitrarily within the period. As such, an output waveform having any desired duty cycle can be created independent of the phase relationship between the two input waveforms.

Abstract: An arrangement which includes apparatus for signifying the source of data to be displayed, apparatus for generating lines of data to fit between the lines of interlaced data to be presented on a non-interlaced output display device, and apparatus for generating lines of data to be presented on an interlaced display from a larger number of lines representing non-interlaced data.

Abstract: A method for reducing interrupt processing overhead is applied in situations when it is not necessary to preserve processor state information. A flag is provided to indicate whether or not the processor is available. Upon recognition of an interrupt, an interrupt vector address is computed based, in part, on the state of the processor available flag. If the processor is available, indicating that it is not currently working on a task, there is no need to preserve the processor state information, and the state-saving portions of the interrupt processing routines are bypassed. On the other hand, if the processor is not available, indicating that it is engaged in a task, the state information must be preserved so that the processor can return to the task after the interrupt is processed. In this case, the state-saving portions of the interrupt processing routines are not bypassed.

Abstract: A six degrees of freedom interactive display controller device is disclosed, comprising a hand manipulable housing unit having an opening for the passage of a mouse ball, two motion detectors for detecting the movement of the mouse ball and converting that motion to output signals controlling the tranlational movement of an object on the display of a computer, a finger operated conveyor belt or roller for controlling the translational motion of the object with respect to a third translational axis, a first finger controlled mechanism, such as a wheel and motion encoders, affixed to the housing for controlling the rotational motion (pitch) of the object with respect to a first one of the translational axes, a second finger controlled mechanism affixed to the housing for controlling the rotational motion (roll) of the object with respect to a second one of the translational axes, and a third finger controlled mechanism affixed to the housing unit for controlling the rotational motion (yaw) of the object with re

Abstract: A self-terminating coaxial tap connector for use with an external termination element has two oppositely directed coaxial connector sockets having conncected center conductors and connected surround shields, the connected shields having a mounting tab for attachment to a printed circuit board. Within the connected shields is a secondary conductor parallel and spaced from the center conductors. Within each socket, at an end of the secondary conductor near the end of a center conductor, is a movable switch element connected to the secondary conductor and having a first switch position in contact with the center conductor when the socket is open, and having a second switch position detached from the center conductor when a mating plug connector is coupled to the socket, the switch element being moved to the second switch position by abutment with the mating plug connector.

Abstract: Programmable logic cells, and arrays of those cells, having certain characteristics, including: (1) the ability to program each cell to act either as a logic element or as a logical identity element(s) between one or more inputs and one or more outputs; (2) the ability to rotate circuits by 90.degree. and to reflect circuits about horizontal and vertical axes; (3) an integrated logic and communication structure which emphasizes strictly local communications; (4) a minimal complexity of logic functions available at the cell level, making available a very fine-grained logic structure; and (5) suitability for implementation of both synchronous and asynchronous logic, including speed-independent circuits. Cells are arranged in a grid, with each cell communicating with its north, east, west and south neighbors. The cells are programmable to several states.

Abstract: A compression and expansion apparatus and method for compressing and expanding digital audio signals using adaptive differential pulse-coding-modulation for high fidelity music is described. The apparatus comprises a predictor, a first and second adder, a first and second adjuster, a quantizer, an inverse quantizer and a step-size adaptor. An input digital signal and predicted signal are added by the first adder, producing the difference between the two signals. The output of the first adder is coupled to the first adjuster which acts as a multiplier to alter the gain and normalize the signal. The signal is then quantized by the quantizer. The output of the quantizer is sent to both the inverse quantizer and the adaptor. The adaptor acts like an automatic-gain-control to control the gain provided by the first adjuster. After inverse quantization by the inverse quantizer, the signal is sent to the second adjuster to remove the effects of the first adjuster process, i.e. denormalize and remove gain.

Abstract: An error reducing raster scan method for a raster scan device having multiple simultaneous scan lines, the method including the steps of separating scan lines to be placed adjacent to each other into different scan groups, so that no two scan lines to be placed adjacent to each other are in the same scan group, and a scanning a set of scan lines from a different one of the scan groups on each scan across the area.

Abstract: A self-terminating coaxial connector for installation on the end of a coaxial cable has a coaxial connector plug with a center conductor surrounded by a shield, and within the plug, a switch contact spring and a termination circuit element. The switch contact spring is mounted within the shield substantially parallel to and separated by a spaced gap from the center conductor. The switch contact spring has an end near the center conductor and open end of the plug folded back to cross the spaced gap and movably contact to the center conductor. This movable contact is moved out of contact to the center conductor by coupling of the plug to a mating socket connector. Also within the plug is a termination circuit element connecting from the switch contact spring through the termination circuit element to the shield. This self-terminating plug design has reduced signal reflection and signal radiation problems, and has a simplified mechanical assembly within the connector.