Abstract: A circuit for generating a control signal for use in a communication line duplexer or other isolation means. The transmitted signal at the output of the duplexer is phase detected to detect its real and imaginary components. These components are used to modulate the transmitted signal which is then injected into a feedback loop of the duplexer. This substantially cancels the transmitted signal at the output of the duplexer. The circuit permits the communication line to be terminated in a constant impedance.

Abstract: A microcomputer including a video generator and timing means which provides color and high resolution graphics on a standard, raster scanned, cathode ray tube is disclosed. A horizontal synchronization counter is synchronized at an odd-submultiple of the color subcarrier reference frequency. A "delayed" count is employed in the horizontal synchronization counter to compensate for color subcarrier phase reversals between lines. This permits vertically aligned color graphics without substantially altering the standard horizontal synchronization frequency. Video color signals are generated directly from digital signals by employing a recirculating shift register.

Abstract: An apparatus for digitally controlling the display of color in a phase alternation line (PAL) video display is disclosed. Coded digital signals are shifted in a recirculating shift register. The direction of shifting in the register and the stage at which the signals in the register are sensed are changed as a function of odd/even display lines to compensate for PAL phase reversals.

Abstract: A controller for interfacing between a digital computer and a magnetic disc recorder, such as a "floppy" disc, or other recorder or memory is disclosed. The controller, which permits accessing of the disc with minimum control by the computer, is realized with relatively few components and is particularly suited for interfacing between a microcomputer and a "minifloppy". Track selection with a computed velocity profile is employed. Synchronization with a soft sectored disc is achieved without additional hardware.

Abstract: A microcomputer including a video generator and timing means which provides color and high resolution graphics on a standard, raster scanned, cathode ray tube is disclosed. A horizontal synchronization counter is synchronized at an odd-submultiple of the color subcarrier reference frequency. A "delayed" count is employed in the horizontal synchronization counter to compensate for color subcarrier phase reversals between lines for the non-interlaced fields. This permits vertically aligned color graphics without substantially altering the standard horizontal synchronization frequency. Video color signals are generated directly from digital signals by employing a recirculating shift register.

Abstract: A direct current (DC) power supply of the single-ended flyback type particularly suited for providing power for integrated circuits is described. The power supply is self-exciting and thus does not employ an auxiliary drive or oscillator. The starting/restarting circuitry provides protection against faults. Because of this fault protection, a relatively simple over-voltage circuit is employed at the output of the supply. An additional primary winding is used to provide protection for no-load conditions.