Abstract: This invention relates to electronic circuits that detect changes in digital data that occur on a parallel data bus. The data on the parallel input bus is fed to a memory register. In addition, each data bus is tied to a comparison circuit which compares the input data with the output data on the same bus. If the data is not identical, the comparison circuit changes state to provide a signal which may be used for updating the data.

Abstract: Two video signals are precisely gain balanced so that one video signal may be inserted, unnoticeably, into a display derived from the first of the two video signals. To this end, a strobe is generated as the inset video signal is initiated. Both the inset video and the display video signals are sampled at the time said strobe is generated. A difference signal is derived from both samples and the gain of the inset video channel is adjusted in accord with the magnitude of that difference signal in a manner so as to minimize that magnitude.

Abstract: This invention relates to a system that permits a video tape recorder to simultaneously record a plurality of independently occurring events. The system causes the events to be multiplexed before they are recorded and a coded signal to be recorded on the tape so that when the tape is played back, the events may be demultiplexed in the same order that they were recorded.

Abstract: This invention relates to an electronic processing system that receives instruction and data words from a digital computer and automatically processes the instruction and data words to control the appearance of graphical and written matter on a plurality of display devices. The foregoing is accomplished by storing the instruction and data words in a first-in-first-out memory, decoding the formatted instruction word received from the first-in-first-out memory and routing the data that immediately follows the instruction words to the character and function generators so that the desired information may appear on the screens of the display devices. Thus, this invention reduces the number of computer instructions that are necessary to produce a given set of elements on the display devices so that an additional computer would not be required.

Abstract: A cellulose acetate butyrate lacquer film containing minute beads of the clear lacquer is backed by a reflective surface, to form a high resolution front projection screen of selective gain. The gain of the screen depends upon the thickness of the lacquer film and the reflectivity of the backing member.

Abstract: Light transmission of ends of optical fibers simulating runway lights in a scale-model system is markedly increased by grinding and polishing each such fiber end at an angle which provides total internal reflection of most light in each fiber and consequent light projection in a desired direction at a small angle to a simulated airfield runway surface.