Abstract: A printer having a print engine (13) and a bit map memory (12) including a number of page image areas (31) into which information to be printed is rasterized and from which information for the print engine is serialized. A digital processor (11) controlling the print engine is operable to reduce a page image area (31) to a modified page image area (37) based upon the highest and lowest addresses at which information has been written into the page image area. The digital processor (11) is also operable to begin rasterization of a new page image area when a sufficient amount of an existing page image area (41) has been serialized to make available the requisite bit map memory for the new page.

Abstract: A printer control system which enables the using application program to automatically selectively alter printer default parameters, to automatically selectively delete previously downloaded fonts and macros, and to enable the printer to operate from one of several datastream formats. The system allows the printer to initialize default parameters for a succeeding job during the printing of a current job as long as the datastream format is unchanged, and allows the deletion of downloaded fonts as long as they are not needed for the current or future pages being printed for the current job.

Abstract: A computer system operating under software control to provide output to a printer for printing. The computer system sets printer parameters to accommodate different forms of output to the printer. A word processing program stored in the computer memory is executed to couple information for printing to the printer with the printer in a first set of printer states. A typewriter emulator program stored in the computer memory is executable to couple information for printing to the printer and to set the printer states. The word processing program is interrupted by a hot key depressed by an operator, and the typewriter emulator program is entered, with the printer states being set in dependence upon printer state information for the typewriter emulator. When the typewriter emulator is interrupted by a hot key, the then-current printer states are stored and a set of default printer states for the word processor are restored prior to returning to execution of the word processing software.

Abstract: A page printer including a print engine (15) and a controller (11) which includes a non-volatile memory (16) having an EEPROM (17) and a chip RAM (18). A microprocessor (12) under program control manages the placement of data in the EEPROM (17) of the non-volatile memory (16). The EEPROM (17) and the associated chip RAM (18) are structured to have a control block (31) and a data storage portion (32-39). The control block (31) includes pointers (41-47) indicating the locations in the non-volatile memory where data is stored. If a data location becomes faulty, the value of the pointer to that location is changed so that the pointer points to a previously unused portion of the non-volatile memory.

Abstract: A printer receives and stores coded text character data (22, 23) and also receives graphic image commands in the same datastream. The printer creates a raster image (24) of the graphic image commands and stores the resultant raster image. When rasterizing a page (21), the printer rasterizes the text character data utilizing stored raster fonts and rasterizes the graphic image data from the stored raster image.

Abstract: A continuous form and cutform feeding unit for a printer. The feeding unit permits feeding a continuous form and cutforms utilizing a cutform feeding arrangement and a continuous form tractor feed. In order to permit either type of form to be fed to a main body of a printer, through a single form feeding passage, a cutform feeding passage and a continuous form feeding passage are provided upstream of the single form feeding passage. In the continuous form feeding passage, a continuous form cutting apparatus is operable to cut a continuous form in response to a signal such as for the beginning of the feeding of cutforms.

Abstract: A matrix keyboard system for producing key codes in response to the actuation of key switches. The keyboard system includes ghost key condition detection. In the keyboard system, a group of parallel drive lines and a group of orthogonal parallel sense lines form a matrix, with a key switch being associated with each of the intersection points on the matrix. The drive lines are sequentially activated, and the actuation of a key switch along an activated drive line results in the coupling of a drive signal to the associated sense line. A ghost key condition arises when three of the four corners of a notional rectangle in the matrix contain an actuated key switch. The ghost key condition detector senses the presence of drive signals not only on the sense lines but also on the drive lines, with a ghost key condition being identified if a drive signal is sensed on two or more sense lines and two or more drive lines simultaneously.

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.