Abstract: The present invention provides a method and apparatus for transmitting signals on a transmission line, the transmission line having a DC current flowing therethrough and having a plurality of terminals connected thereto in a multidrop fashion. Each of the terminals is capable of drawing a portion of the DC current. A signal is transmitted on the transmission line by varying the portions of the DC current drawn by the terminals. When the signal is not being transmitted the total amount of the DC current drawn by the terminals from the transmission line is maintained at a value smaller than an average amount of the DC current drawn by the terminals from the transmission line when the signal is being transmitted.

Abstract: A data processing system including a data transfer abnormality processing unit in which delays caused by the production of a data transfer abnormality signal during a data transfer cycle period are eliminated. A bus controller, a memory unit and one more data processing units are connected in parallel to a common bus which includes a data transfer abnormality signal line. The bus controller includes a data register which receives data from the common bus, delaying it for one cycle period before applying it to a transfer abnormality check circuit. The transfer abnormality signal produced by the transfer abnormality check circuit is stored in a transfer abnormality setting flip-flop in each data processing circuit with a clock pulse which is produced delayed with respect to a bus use permission signal.

Abstract: A two-way transmission system including a master station coupled to a transmitting end of a transmission line and a sub station coupled to the receiving end of the transmission line. A pulse transformer is provided between the transmission line and at least one of the master and sub stations. Variations in current flowing through the winding of the pulse transformer coupled to the transmission line produce variations in the impedance of the secondary winding which are detected with a comparator circuit to produce an output received signal. A diode may be inserted in series with the transmission line at at least one of the receiving and transmitting ends of the transmission line to prevent the charging of the distributed capacitance of the transmission line to increase the maximum possible transmission rate.

Abstract: A ring-configured network of multiple inter-communicating data stations in which each data station includes a fault sensing circuit, a test-pulse generating circuit and a switching circuit as well as a transmitter circuit and a receiver circuit, and the test pulse generating circuit responds to a sensed fault to transmit, sequentially, in opposite directions along the ring, test signals which, in combination with the fault sensing circuit, indicate the direction of any fault and terminate the line in the direction of the fault at the characteristic impedance of the line. Thus, normal communications can continue between the stations despite the fault.

Abstract: In a common-bus data transmission system, a "collating unit" is added to the port unit of a multimode terminal to compare the received instruction "mode assignment code" with the previously-set "mode setting" for agreement before allowing communication.

Abstract: An information processing system of the type having a plurality of stations interconnected via transmission lines. Each station is of the type which includes control devices, processing devices which respond to information sent thereto and which generate information to be sent to other processing devices at other stations, and communicating devices for transmitting and receiving information to and from the stations. In the information processing system, transmission and reception between two adjacent stations is independent of transmission and reception between any two other adjacent stations. A system is disclosed which prevents the stoppage of information transmission as a result of a build up of information at other than the given station. Apparatus is provided for detecting when a stagnation condition occurs and for temporarily increasing the length of the buffer registers in the communicating devices of the stations.

Abstract: In an information processing system of the type having widely dispersed terminals tied together by a series communications link, common data which is of interest to all stations is collected and registered in a simplified manner. The common information, consisting of the status of each of the stations, is collected by any station sending out a search instruction as part of an information word. As the information word passes through each successive station, each respective station adds a status bit to the information word indicating the status thereof. When the new-completed information word returns to the originating station, the common data is registered and displayed. Also the common data is sent, along with a "register common data" instruction, to all other stations via the communication link. Upon receipt of such information and instruction, each station registers and displays the common data.

Abstract: In an information system of the type having widely dispersed terminals tied together in series by an information transmission line. Bypassing means is provided for bypassing a non-operating station so as not to disrupt said information transmission line, apparatus is provided for preventing any station from dispatching information destined for a non-operating station.