Abstract: There is disclosed herein a forms feed tractor mechanism having a belt with pins and driving elements extending threrethrough. The pins are adapted to engage perforated holes along the edge of a recorded medium. Driver means are provided for rotating the belt and pins and thereby rotate the engaged medium. Also, there is provided a spring tensioner for maintaining tension on the belt. The tractor includes a door which is rotatably snapped fitted into the housing of the tractor and maintained above the plane of the record medium by an extension on the lower surface thereof. The belt and pins are constructed by molding the pins around the belt side so that the belt is below the feeding surface of the tractor mechanism upon which the paper rests.

Abstract: A printer subsystem is interconnected with a host system from which it receives command and data information and to which it provides status information. The printer subsystem has two microprocessors, one of which communicates with the host system for transfer of command, data, and status signals and the other of which directly controls the printer unit in the subsystem especially with respect to the print assembly, forms feed assembly, ribbon drive assembly, and print wire actuators.

Abstract: An information transfer system is described that includes a central processing unit (CPU) interconnected with a peripheral device such as an operator console by an interface bus of finite capacity. Transfer of information in the system is normally in a preferred direction from the CPU to the console. Provision is made to transfer information concerning key depressions on the console from the console to the CPU without using the bus by utilizing a normally continuously operating counter in the CPU that provides a sequence of coded count signals representative of individual keys that are provided on the console and that may be depressed. A comparator in the console compares coded count signals from the CPU counter with coded signals from the console representative of actual key depressions and provides a stop signal to the CPU counter via a single control line when an equal compare of the CPU counter and console coded signals occurs.

Abstract: In a computer system, paging operates and a method of use thereof are provided for extending the addressing capability of a processor by using a page register. The page register includes means for storing different codes for different operations to be performed on the memory. The memory is divided into four groups of memory within 2.sup.n addresses such that there is paged and unpaged ROM and paged and unpaged RAM. The unpaged ROM and RAM include only a single block which is directly addressed by the n bit address bus. The paged ROM and RAM includes a plurality of blocks or pages, one of which is selected to be addressed by the page register. The page register responds to the address bus and to signals from the processor defining the memory operation to be performed by providing page signals, selecting one page of paged memory.

Abstract: A processor intercommunication system includes a plurality of stations which are interconnected by a transmission link, each station having an associated processor. Further, each station comprises means which provide a data link protocol mechanism for establishing and maintaining a multiplicity of logical connections or transfer sessions between the station and several other stations. Thus application programs of all kinds in the processors can communicate with programs or data files in remote processors and need not be involved in communication operations which are handled by the stations. Link access circuitry is provided also in each station for absorbing the physical and topological characteristics of the transmission link so that the data protocol circuitry establishing and maintaining logical connections is independent of these characteristics.

Abstract: There is disclosed herein a dot matrix tilting print head assembly in which the print head is rotatably mounted in frame means. Solenoid means are provided for rotating the print head a controlled distance so that printing occurs between previously printed dots. Means are provided for controlling the distance to be one half of the center-to-center distance between printed dots. This entails maintaining very low tolerances for the mechanically moving parts. In addition, there is provided means for removing the print head alone from the frame means.

Abstract: In a loop-structured communication system interconnecting a plurality of data processors without central controller, stations comprise modems which can start loop operation and achieve synchronous frame transmission around the loop through all participating stations.In an initialization procedure after system start or after loss of frame synchronization on the loop, modems select a temporary master station.The temporary master will adapt total loop delay to be an integer multiple of the basic frame period, and will transmit available frames. All active modems adapt their timing to the circulating stream of frames until the whole loop and all participating stations are synchronized.Synchronization conditions are continuously monitored in all stations to start resynchronization or initialization procedures if necessary. In a specific arrangement, the location of a loop failure which prevents establishment of synchronization can be determined.

Abstract: A printer is provided with facilities for increasing the printing throughput. This involves a partial line turnaround operation. The printer has means to move a form or document past a print line, a ribbon drive assembly, and a print assembly incorporating a plurality of print wires arranged in print head groups, each group comprising a predetermined number of print wires. If, as an example, the print assembly has two, four, six, or eight print heads, each can accommodate eight wires in the embodiment described. The print wires are arranged in a slanted serrated pattern and provision is made herein to insure that the print heads move at least far enough to print their assigned character locations prior to the performance of any turnaround in individual lines being printed. Routine involves the accessing of tables stored in conjunction with a microprocessor, the tables indicating the optimum turnaround situations for the different print head configurations.

Abstract: A synchronous data transmission system between remote stations is shown wherein data is transmitted parallel by bit serial by group over a plurality of parallel lines extending between sending and receiving stations. A parity line is also included in the transmission system for checking errors and a clock line is included for synchronization of the parallel data being transmitted. Information is transmitted from one station to another with alternating even and odd parity for succeeding groups of parallel data. The information is checked at the receiving station for even-even or odd-odd parity in succeeding groups of data. Longitudinal redundancy checking (LRC) is also added to the checking at a receiving station. The combination of the even and odd parity checking and the LRC checking provides a level of data transmission error checking which is almost as effective in finding errors as a far more costly CRC checking mechanism.

Abstract: A wire matrix printer has a plurality of heads, each consisting of nine wires arranged in a slanting format. The printer can be controlled to print Oriental type characters such as Japanese by loading a wire image map of the characters into a memory. The loading technique loads the memory in a slanted fashion corresponding to the slant of the print heads and reads from the memory in a bit column manner to correspond to the position of the various wires of the multihead print block. The loading and unloading of the wire image memory is controlled by a pair of microprocessors operating respectively on different halves of the memory, such that at any given time, half of the memory is being loaded while the other half is being read from. Thereafter, the memory is switched so that the loaded half is read and the previously read half is cleared and loaded with a new line of information.

Abstract: There is disclosed herein a dot matrix tilting print head assembly in which the print head is rotatably mounted in a frame. A solenoid is provided for rotating the print head a controlled distance so that printing occurs between previously printed dots. A pin extending from the print head is positioned into a larger diameter hole in the frame for controlling the distance to be one half of the center-to-center distance between printed dots. This entails maintaining very low tolerances for the mechanically moving parts. In addition, there is provided support members for allowing the removal of the print head alone from the frame means.

Abstract: There is disclosed herein printer control logic for controlling a matrix printer. The control logic includes an interruptable microprocessor, together with associated memory. Additionally the control logic includes a programmable timer which provides a signal a determined time after being programmed. The control logic responds to print emitter signals manifesting an incremental movement of the print head by interrupting the microprocessor. The microprocessor then programs the timer to provide signals after a programmed delay time to again interrupt the microprocessor. The microprocessor then provides signals causing the operation of the print elements on print head.

Abstract: In a data processing system, a mechanism provides independent assignment of page locations for a program's instructions and its data and better enables control to be transferred between programs, or portions thereof, that reside at different addresses in different pages of a multiple page instruction store. The initial linkage is established through the use of a Branch And Link instruction. Subsequent linkages are established through the use of Return and Link instructions, each of which transfers control to a previous program, or program segment, while simultaneously establishing the linkage for a subsequent return to this program or program segment.INTRODUCTIONCROSS REFERENCES TO RELATED APPLICATIONSU.S. Patent application of J. D. Dixon, one of the co-inventors herein, Ser. Nos. 866,425, filed Jan. 3, 1978 and 918,223, filed of even date herewith, both assigned to the assignee of the present invention, show and describe, but do not claim, portions of the invention claimed in the present invention.

Abstract: A cathode ray tube (CRT) and keyboard display terminal are operated in accordance with the program routines of a microcontroller. The microcontroller includes a random access store which is loadable by the customer during initial program load (IPL) operation to store customer selected program routines for controlling the CRT display and keyboard and for initializing tables in the store which define the customer selected character and symbol set. The tables provide data for determining the functions which are to be performed incident to the depression of each key and since these are customer loadable, the functions can be changed by reinitializing the system. These tables provide the mechanism whereby an operator making use of the keyboard can manually change the functions of each and every key on the keyboard except one key which is dedicated to the function of redefining the functions of other keys.

Abstract: A micro processor controlled user programmable communications multiplexer subsystem (herein referred to by the symbol PCS) capable of transmitting and receiving data on any one or more of 32 communications lines simultaneously. Each line may be dynamically assigned to a variety of communication characteristics, such as line speeds, character lengths, synchronous, or asynchronous operation, and code structures as well as protocol selections.The system of the invention provides the capability for the user to write his communications programs using novel operations commands that provide code structure and protocol independence as well as communication line independence. Various hardware features and queuing techniques are employed in order to maintain high transmission rates.Variable line scanning in the Teleprocessing Time Division Multiplexer of the PCS is programmably permissible; i.e.

Abstract: A method and apparatus is shown for improving the clarity and character density on a cathode ray tube (CRT) display in which characters are formed row by row from discrete character elements in row and column coordinate matrices. Unblanking signals form the discrete character elements no less than two matrix spaces wide every time an unblanking signal is applied. This technique results in a much crisper appearance to the characters on the screen and permits as many as 128 characters per line using a low cost commercially available television (TV) monitor. A random access storage is used to store dynamically the addresses of positions (locations) of a read only store corresponding to characters to be displayed. The read only store (ROS) contains indicia corresponding to the discrete character elements of a plurality of characters, one set of indicia for each character in the desired character set.

Abstract: A data processing system is described which has multiple sets of registers each of which is capable of autonomously controlling a common storage and common arithmetic and logic control circuits to execute respective tasks of a program. Level status blocks (LSBs), each assigned to a respective task, are held in main storage; and each contains such address and status data as is required for task execution in a controlled environment.