Abstract: A system for controlling the flow of data over a common bus between a plurality of processing units is disclosed which preferably includes a MOS/LSI circuit controller chip associated with each processing unit for awarding priority of access to the common bus when two or more processing units attempt to simultaneously gain access to the common bus. A contention circuit located in each controller chip is responsive to the sensing of each bit in the address of its associated processing unit, and generates a plurality of transitions on the common bus during the time a binary one bit is sensed in the address and listens for the presence of any transition on the common bus during the time a binary zero is sensed in the address. Access to the common bus is lost when transitions are detected on the bus during the time a binary zero bit is sensed and acquired when no transitions have been detected at the completion of the sensing of the address of the requesting processing unit.

Abstract: A system for processing data used by a recognition system in recognizing an unknown character. A multi-channel read member generates a plurality of parallel rows of data bits which taken together form an image of the character to be recognized. In order to align the rows of data in their proper relationship, each row of data bits is examined to determine if the row contains data representing a feature characteristic of the unknown character or a clear channel. The top row of the character is selected as the first row of data bits representing a feature characteristic of the character which follows the largest number of consecutive clear channel rows. The top two rows of the character are then compared. The row having the greatest number of feature characteristic data bits is selected as the top row of the character. Signals identifying the top row of the character are generated for us by a recognition apparatus in recognizing the unknown character from the rows of data bits generated.

Abstract: Apparatus for generating a scanning pattern for the omni-directional reading of bar code indicia. In one embodiment, a rotating mirror assembly is imaged onto itself by a lens and mirror combination which introduces a light displacement of the image resulting in the displacement of the input beam from the angle of incidence on the mirror of the input beam. Using an array of such lenses and mirrors, a plurality of spatially displaced light beams of substantially equal power are generated without the use of specialized beam-splitting coatings for use in the generation of a scan pattern. In a second embodiment, the array of mirrors deflects a laser beam two or more times at the same facet of a rotating mirror assembly to increase the angular velocity of the deflected beams, thereby enabling the mirror assembly to be rotated at a lower speed while still maintaining the required angular velocity of the deflected output beam.

Abstract: An integrated circuit chip for controlling the transmission of data between a host peripheral device and other peripheral devices or a remote processor in which the transmission of data takes place in either a processor interrupt mode or a direct memory access mode. The integrated circuit chip includes first, second, third and fourth sequentially located edges forming a rectangle. The chip further includes input circuitry located generally adjacent the corner formed by the third and fourth edges and output circuitry located adjacent the first edge. A plurality of counters/registers associated with the input and output circuits are located adjacent the third edge. A Command register located adjacent the third edge selects the transfer mode and controls the operation of the integrated circuit chip in either an output or input mode. The chip may operate in a transmit only mode, receive only mode or transmit and receive modes simultaneously.

Abstract: A single drive mechanism providing selective feeding of at least two printing media and independent bi-directional movement of the media in the operation of a single print station. The drive mechanism including a platen member is movable to allow the two printing media to be positioned in the print station for a printing operation. The platen member is rotated in opposite directions to feed the two printing media to a printing position.

Abstract: A reader for punched hole cards having a movable housing member containing a coil spring is disclosed, the housing member is actuated by a card inserted in the reader and moved to an activated position against the action of the spring. Secured to the housing member is an air vane governor rotated upon movement of the housing member to an inserted position. Upon release of the card, the card is driven past sensing members by the spring at a constant speed controlled by the rotating air vane governor. Timing means associated with the punched hole configuration of the card being read is provided.

Abstract: A feed mechanism for moving a record member into a printing position in which a single control solenoid is energized to enable a pair of drive rollers to move a multi-form record member from a holding position to a printing position. Operation of the solenoid further moves a platen member into engagement with the record member which is spring urged to enable the platen to apply a force on the record member. The force on the platen is selected to compensate for the thickness of the record member allowing a dot matrix printer to print satisfactorily on record members of varying thicknesses. The drive rollers are normally positioned to locate a record member in a validating printing position. Spring means are associated with the drive rollers to engage and hold the record member in a printing position during the operation of the solenoid.

Abstract: A digital controller used in regulating the output of a power supply including a diagnostic circuit for sensing the failure of a component in the power supply. Upon the occurrence of a fault, signals are generated locating the component which caused the shutdown of the power supply. The fault signals are inputted into a plurality of encoders which determine the priority between two or more simultaneous occurring faults and which further outputs binary signals identifying the faulty component. The binary signals are then latched and displayed in a LED display which may be actuated any time after the fault has occurred by the operation of a switch member.

Abstract: A membrane type keyboard associated with a data terminal device is disclosed which is sealed to prevent the introduction into the interior elements of the keyboard of water or other types of liquid contaminants encountered during the operation of the terminal device. The keyboard includes an outer frame member which forms an air chamber extending around the perimeter of a raised keyboard, thereby preventing any liquid spilled on the keyboard from reaching the interior elements of the keyboard. The frame member is easily removable from the keyboard, allowing the interior elements to be replaced or exchanged in accordance with the business environment in which the terminal device is to be used.

Abstract: An integrated circuit for operatively connecting a plurality of peripheral devices to a processor includes first, second, third and fourth sequentially located edges forming a rectangle. The integrated circuit includes two independent full duplex, master peripheral ports in which each port provides two character buffering on both input and output channels. Data may be transmitted using two message formats at two different clock frequencies with each channel having simultaneous sending and receiving capabilities. Data processing circuits are located adjacent the first edge which connects to the processor while the port control circuitry is located adjacent the third edge of the chip which connects to the peripheral devices.

Abstract: A printing system for printing coded bar elements on a record member include a rotatable drum member having slidably mounted print elements disposed about its periphery. An actuator member positioned adjacent the drum member engages one of the print elements upon movement of the drum member to position a print element adjacent a record member. The actuator member is operated to slide the engaged print element to a printing position enabling the print element to print a coded bar on the record member.

Abstract: A control circuit to disable the operation of a semiconductor microprocessor memory device in event of an unauthorized attempt to access the memory. The memory device is disabled from operation upon removal of the device from the microprocessor. A delayed signal generated outside the memory device enables the control circuit to generate a memory enabling signal. Logic circuit means including a counter generates a signal for a preselected time period during which the delayed signal is required to be generated. Both signals control the enabling of the memory device.

Abstract: A method and apparatus for synchronizing a digital data demodulator to a received phase modulation carrier signal in which the carrier signal is phase shifted during each modulation period of the carrier to represent one of four pairs of binary bits or dibits. A first dibit clock is adjusted to the phase of a reference dibit clock whose output is used to synchronize the demodulator in establishing the location of the modulation period of the incoming carrier. In order to overcome errors found in the decoding of the carrier signal, the adjustment of the dibit clock is suppressed when the dibits 00 and 10 are being decoded. With this construction, it was found that the dibit clock may run out of synchronization if long strings of zero characters (dibits 00) are received. In order to solve this problem, a second dibit clock is employed which is adjusted on dibits 00.

Abstract: A digital controller includes a digital feedback circuit for use in generating a pulse-width modulated control signal. The signal is derived from binary signals representing a standard pulse-width signal for the rated output of the power supply plus a correction pulse-width signal reflecting the change in the output level of the power supply. Logic circuits alter the correction pulse-width signals to provide a balancing correction. Soft start operation of the power supply together with a selection of operating clock frequencies are also provided.

Abstract: A digital controller for a power supply which includes a transformer having primary and secondary windings and switching transistors for switching a current from a D.C. input means through the winding of the transformer to an output circuit. Pulse-width modulated control signals are used to control the switching operation of the transistors. In order to correct for an imbalance in the operation of the transistors, an error signal is developed which alters the value of the duty cycle of the transistors forcing the B-H curve of the transformer to oscillate between upper and lower threshold values.

Abstract: A system for driving a plasma display panel is disclosed in which a transformer operated at a system clock frequency supplies voltage pulses to both the electrodes in the cells of the display device. Switching members operated by control signals generated by a control member select the cells to be discharged. A circuit for regulating the transformer output voltage in accordance with the number of cells discharged is also disclosed.

Abstract: A holographic scanning system for scanning bar code indicia is disclosed in which the light beam of a laser is directed to a first set of holograms located on a single rotating disc in which each hologram will generate an individual scan beam having a slightly different focal length and direction angle from that of the other holograms. The generated scanning beams are directed on a target area through which passes a label or object bearing a bar code indicia. Each of the scan beams is projected in an overlapping relationship on the target area, thereby providing an enhanced depth of focus enabling a more effective reading operation. The light reflected from the bar code indicia is picked up by a second set of holograms mounted on the rotating disc and focused at a point at which is located an optical detector for use in reading the bar code.

Abstract: An apparatus for reading data printed on a flexible document in which the document is orientated in a vertical direction during the reading operation. The document is initially positioned on a movable support member located in the path of movement of a scanning head. Movement of the document against the support member enables a clamping member to clamp the document in a sensing position, an actuator member for moving the support member out of the path of movement of the scanner head and moving the scanning head in a longitudinal direction to read the data on the document.

Abstract: A driving circuit for a gas-discharge display device includes a pair of switching members and the secondary windings of a transformer wired in series with one of the switching members. The switching members in response to receiving out-of-phase control signals alternately apply a low voltage pulse to the display device. The secondary windings of the transformer output continuously a high voltage pulse in phase with one of the switching members. Upon the generation of appropriate control signals enabling the operation of the switching members, a voltage of sufficient magnitude is applied to selected cell segments in the display device to fire the cells. The transformer together with the low voltage pulses are driven by a high frequency clock to provide a high intensity display operation.