Abstract: A correction buffer for a typing system in which the correction buffer has a group of records, each record corresponding to an incremental distance on the medium which is printed upon. The records in the correction buffer contain information concerning characters entered through a keyboard by a typist including designations of entered characters and character attributes.

Abstract: A thermal printhead, which is pivotally mounted on a carrier, is moved into and out of its printing position by a four bar linkage, which is responsive to the direction in which the carrier is being advanced, rendering a spring, which urges the thermal printhead into its printing position, effective and ineffective. When the carrier is advanced from left to right to print, the linkage responds to a drive mechanism for the carrier to enable movement of the printhead into its printing position by the spring prior to the carrier drive mechanism moving the carrier. When the carrier is to be moved from right to left in the non-printing direction, the linkage responds to the initial motion of the carrier drive mechanism in this direction to render the spring ineffective and to move the printhead out of its printing position prior to the carrier drive mechanism moving the carrier.

Abstract: A method and apparatus for printing characters in bold form in a typing system. As disclosed, characters entered through an input device such as a keyboard are printed on paper, placed in a display and stored in memory substantially as they are entered. After a group of characters, such as a line of characters, have been entered and printed, those characters which are to be printed in bold form are identified from the information stored in the memory. The thus-identified characters are then printed a second time at a position slightly offset from that of the first printing of each of the characters.

Abstract: A DC to DC power converter having reduced switching loss for operation at high frequencies. As disclosed, a buck, or forward, converter includes a first FET as the switching device in series with an inductor and a second FET as the flywheel device. At the common node to which the two FET's and the inductor are connected, there is sufficient capacitance that the FET's may be turned off without appreciable voltage change across the FET's. The value of the inductor is chosen, with respect to the input and output voltages and frequencies of operation involved, to insure that the inductor current polarity reverses each cycle, raising the node voltage to the level of the input voltage, substantially eliminating turn-on losses of the first FET. Control circuitry is provided for regulation of the power converter to control the peak-to-peak current in the inductor and to insure that at least a selected minimum value of the inductor current is present for each cycle of operation of the converter.

Abstract: A DC to DC power converter having reduced switching loss for operation at high frequencies. As disclosed, a buck, or forward, converter includes a first FET as the switching device in series with an inductor and a second FET as the flywheel device. At the common node to which the two FET's and the inductor are connected, there is sufficient capacitance that the FET's may be turned off without appreciable voltage change across the FET's. The value of the inductor is chosen, with respect to the input and output voltages and frequencies of operation involved, to insure that the inductor current polarity reverses each cycle, raising the node voltage to the level of the input voltage, substantially eliminating turn-on losses of the first FET. Control circuitry is provided for regulation of the power converter to control the peak-to-peak current in the inductor and to insure that at least a selected minimum value of the inductor current is present for each cycle of operation of the converter.

Abstract: In a chopper keyer electronic organ system, a sampling network samples the drawbar inputs to the chopper keyers in order to provide a separate channel of percussion. The drawbar lines for one or more of the footages are sampled and the sample signal is amplified and shaped to provide touch envelope percussion in addition to the sounding of the chopper keyer outputs. Alternatively, the chopper keyer outputs may be disabled and separate voicing such as for piano, harpsichord or steady tones provided via the drawbar sampling circuitry.

Abstract: In a keyboard electronic musical instrument such as an electronic organ, an electro-mechanical memory device for holding in the down or actuated position one or more simultaneously depressed accompaniment chord and bass playing keys after the finger pressure from the instrument player is removed. The signal representing the note or chord associated with the depressed key or keys is sustained as long as the keys remain latched down. A plurality of keys of the lower or accompaniment manual are adapted to be retained in the depressed position and operate as part of the electro-mechanical memory device. When a key or group of keys are latched down, the depression by the instrument player of another key releases the previously retained keys but the newly depressed key is latched down. The electro-mechanical memory also operates in conjunction with the touch mode of the automatic rhythm unit to provide a rhythm signal when the accompaniment keys are retained in the depressed position.

Abstract: An electronic sound generation system wherein an input signal is frequency modulated, and the modulated signal passes through a series of cascaded shift registers. Amplifiers are provided for compensation of insertion loss in each shift register stage, and a frequency modulation detector is utilized to produce the time-delayed output echo signal.