GB1494841A - Data communications system - Google Patents

Data communications system

Info

Publication number
GB1494841A
GB1494841A GB1515875A GB1515875A GB1494841A GB 1494841 A GB1494841 A GB 1494841A GB 1515875 A GB1515875 A GB 1515875A GB 1515875 A GB1515875 A GB 1515875A GB 1494841 A GB1494841 A GB 1494841A
Authority
GB
Grant status
Application
Patent type
Prior art keywords
terminal
message
bits
terminals
address
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB1515875A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NCR Corp
Original Assignee
NCR Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/28Data switching networks characterised by path configuration, e.g. local area networks [LAN], wide area networks [WAN]
    • H04L12/40Bus networks
    • H04L12/40006Architecture of a communication node
    • GPHYSICS
    • G06COMPUTING; CALCULATING; COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F13/00Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
    • G06F13/14Handling requests for interconnection or transfer
    • G06F13/20Handling requests for interconnection or transfer for access to input/output bus
    • G06F13/22Handling requests for interconnection or transfer for access to input/output bus using successive scanning, e.g. polling
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00Data switching networks
    • H04L12/28Data switching networks characterised by path configuration, e.g. local area networks [LAN], wide area networks [WAN]
    • H04L12/40Bus networks
    • H04L12/403Bus networks with centralised control, e.g. polling

Abstract

1494841 Data transmission; master and slave systems NCR CORP 14 April 1975 [24 April 1974] 15158/75 Heading H4P [Also in Division G4] A data handling system includes a central unit, a plurality of addressable terminals each of which may be active or inactive, and a communications adapter coupled to the central unit and arranged to tramsit messages to the terminals, the adapter including a counter arranged to address the terminals and recirculating storage means arranged to store bits provided by the central unit and representing the activity states of the terminals, the arrangement being such that a message is sent to an addressed terminal only if it is active. The system includes a central processor coupled to groups of terminals via respective adapters, each terminal including an input keyboard, a digit display, and a microprocessor arranged to operate ON or OFF-LINE from the central processor. Each terminal may include other devices, e.g. magnetic credit card readers, coin dispensers &c. Each adapter may be connected to up to 16 terminals each of which receives all messages transmitted and, on receiving a message addressed to it, responds with a message. All messages have a similar format including 8 sync bits, 4 address bits identifying a terminal, further address bits identifying a unit within a terminal, data bits, 2 function bits indicating the mode, and check bits including a cyclic redundancy check bit and a 1-bit module two count of the message number. The system is described in some detail in block diagram form and includes features to compare received address bits with stored address bits, and received check bits with generated check bits. Communication is in two modes, viz "polling" where the terminals are addressed in sequence and "exchange" where a selected terminal is addressed. During polling a counter produces the addresses of successive terminals, an activity bit at the output of a recirculating shift register being examined for each address. If the bit indicates an active terminal a message is sent and a timer is set. On receipt of a message a terminal responds. If the adapter recognizes a response before the timer times out and the message is correct all is well. If however the message is incorrect the adapter interrupts the central processor which normally instructs the adapter to repoll the terminal. A similar procedure occurs if no response is received before the timer times out. If after three attempts no valid response is received the control unit regards the terminal as inactive, resets the activity bits accordingly, and resets the address counter to restart the polling sequence. Data transmitted both from the adapter and the terminals is retained following transmission for possible re-transmission in the event that the first transmission is not received correctly. If for any address the activity bit indicates an inactive terminal, no message is sent and the address counter is incremented to address the next terminal. The procedure for an exchange message is generally similar except that the terminal addresses are derived directly from the central unit and the activity bits are not considered. Operation at the adapter and terminals are controlled by sequence counters stepping through sequences of states in response to clock signals and the status of the system. The clock signals are also used to control message transmission and reception, messages being transmitted serially in Manchester code.
GB1515875A 1974-04-24 1975-04-14 Data communications system Expired GB1494841A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US3866175A US3866175A (en) 1974-04-24 1974-04-24 Data communication system between a central computer and a plurality of data terminals

Publications (1)

Publication Number Publication Date
GB1494841A true true GB1494841A (en) 1977-12-14

Family

ID=23840764

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1515875A Expired GB1494841A (en) 1974-04-24 1975-04-14 Data communications system

Country Status (3)

Country Link
US (1) US3866175A (en)
DE (1) DE2517831C3 (en)
GB (1) GB1494841A (en)

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GB2140940A (en) * 1980-02-19 1984-12-05 Omron Tateisi Electronics Co Data communication control system
US4639889A (en) * 1980-02-19 1987-01-27 Omron Tateisi Electronics Company System for controlling communication between a main control assembly and programmable terminal units

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US4027289A (en) * 1975-06-26 1977-05-31 Toman Donald J Operating condition data system
US4071887A (en) * 1975-10-30 1978-01-31 Motorola, Inc. Synchronous serial data adaptor
DE2726860C3 (en) * 1976-06-16 1979-12-13 Tokyo Electric Co., Ltd., Tokio
CA1086397A (en) * 1976-09-14 1980-09-23 Charles G. Diefenderfer Polling an data communication system having a pulse position to binary address conversion circuit
US4100533A (en) * 1976-12-06 1978-07-11 Bell Telephone Laboratories, Incorporated Multipoint polling technique
US4068213A (en) * 1976-12-23 1978-01-10 Ncr Corporation Checkout system
US4142156A (en) * 1976-12-23 1979-02-27 Veripen, Inc. Control signal apparatus for CATV system
US4220991A (en) * 1977-10-08 1980-09-02 Tokyo Electric Co., Ltd. Electronic cash register with removable memory packs for cashier identification
US4241330A (en) * 1978-09-28 1980-12-23 General Atomic Company Multiple-processor digital communication system
US4231015A (en) * 1978-09-28 1980-10-28 General Atomic Company Multiple-processor digital communication system
US4641364A (en) * 1978-12-08 1987-02-03 Motorola, Inc. Function coding via digital addresses in a two-way system
US4251865A (en) * 1978-12-08 1981-02-17 Motorola, Inc. Polling system for a duplex communications link
US4232294A (en) * 1979-04-30 1980-11-04 Control Data Corporation Method and apparatus for rotating priorities between stations sharing a communication channel
JPS5820071B2 (en) * 1979-06-15 1983-04-21 Omron Tateisi Electronics Co
US4388690A (en) * 1979-10-11 1983-06-14 Ael Microtel Limited Automatic meter reading transponder
JPS57182270A (en) * 1981-04-30 1982-11-10 Sharp Corp Electronic cash register system
US4456957A (en) * 1981-09-28 1984-06-26 Ncr Corporation Apparatus using a decision table for routing data among terminals and a host system
JPH0253836B2 (en) * 1981-12-02 1990-11-19 Glory Kogyo Kk
JPS58147270A (en) * 1982-02-26 1983-09-02 Ricoh Co Ltd Fascimile system
US4744024A (en) * 1982-08-27 1988-05-10 Burroughs Corporation Method of operating a bus in a data processing system via a repetitive three stage signal sequence
US4710871A (en) * 1982-11-01 1987-12-01 Ncr Corporation Data transmitting and receiving apparatus
JPS6030252A (en) * 1983-07-29 1985-02-15 Ricoh Co Ltd Facsimile repeating system
US4653009A (en) * 1983-09-21 1987-03-24 Pitney Bowes Inc. Stamp dispenser
US4553263A (en) * 1983-12-22 1985-11-12 Motorola, Inc. Queued community repeater mobile
US4683531A (en) * 1984-07-02 1987-07-28 Ncr Corporation Polling method for data processing system
US4654656A (en) * 1984-09-17 1987-03-31 International Business Machines Corp. Off-line notification and communication network
US4773001A (en) * 1985-10-02 1988-09-20 International Business Machines Corp. Method and apparatus for communicating with remote units of a distributive data processing system
USRE38419E1 (en) 1986-05-13 2004-02-10 Ncr Corporation Computer interface device
DE3855615T2 (en) * 1987-04-09 1997-03-06 Tandem Computers Inc Automatic determination of the number of processor modules for multiprocessor systems
EP0377684A1 (en) * 1988-03-25 1990-07-18 Ncr International Inc. Point of sale system
US5023891A (en) * 1989-07-25 1991-06-11 Sf2 Corporation Method and circuit for decoding a Manchester code signal
FR2658690B1 (en) * 1990-02-21 1992-04-30 Alcatel Business Systems Arrangement for connecting digital terminals has a single port having a higher throughput.
US5278829A (en) * 1991-01-10 1994-01-11 Digital Equipment Corporation Reduced broadcast algorithm for address resolution protocol
FR2765429B1 (en) * 1997-06-30 2000-09-08 Canon Kk Allocation of an access permissions plurality of elements has a Shared Resource
US7076716B1 (en) * 1998-04-13 2006-07-11 Intel Corporation Early acknowledgement of primary packets
US6725218B1 (en) 2000-04-28 2004-04-20 Cisco Technology, Inc. Computerized database system and method
US6804815B1 (en) * 2000-09-18 2004-10-12 Cisco Technology, Inc. Sequence control mechanism for enabling out of order context processing
US7236490B2 (en) * 2000-11-17 2007-06-26 Foundry Networks, Inc. Backplane interface adapter
US7356030B2 (en) * 2000-11-17 2008-04-08 Foundry Networks, Inc. Network switch cross point
US7596139B2 (en) * 2000-11-17 2009-09-29 Foundry Networks, Inc. Backplane interface adapter with error control and redundant fabric
DE10063350C1 (en) * 2000-12-19 2002-07-18 Siemens Ag A method for monitoring a data processing and transmission
US7468975B1 (en) 2002-05-06 2008-12-23 Foundry Networks, Inc. Flexible method for processing data packets in a network routing system for enhanced efficiency and monitoring capability
US20090279558A1 (en) * 2002-05-06 2009-11-12 Ian Edward Davis Network routing apparatus for enhanced efficiency and monitoring capability
US7187687B1 (en) 2002-05-06 2007-03-06 Foundry Networks, Inc. Pipeline method and system for switching packets
US20120155466A1 (en) * 2002-05-06 2012-06-21 Ian Edward Davis Method and apparatus for efficiently processing data packets in a computer network
US7266117B1 (en) * 2002-05-06 2007-09-04 Foundry Networks, Inc. System architecture for very fast ethernet blade
US6901072B1 (en) * 2003-05-15 2005-05-31 Foundry Networks, Inc. System and method for high speed packet transmission implementing dual transmit and receive pipelines
US7817659B2 (en) 2004-03-26 2010-10-19 Foundry Networks, Llc Method and apparatus for aggregating input data streams
US8730961B1 (en) 2004-04-26 2014-05-20 Foundry Networks, Llc System and method for optimizing router lookup
US7657703B1 (en) 2004-10-29 2010-02-02 Foundry Networks, Inc. Double density content addressable memory (CAM) lookup scheme
US8448162B2 (en) * 2005-12-28 2013-05-21 Foundry Networks, Llc Hitless software upgrades
US7903654B2 (en) * 2006-08-22 2011-03-08 Foundry Networks, Llc System and method for ECMP load sharing
US8238255B2 (en) * 2006-11-22 2012-08-07 Foundry Networks, Llc Recovering from failures without impact on data traffic in a shared bus architecture
US20090279441A1 (en) * 2007-01-11 2009-11-12 Foundry Networks, Inc. Techniques for transmitting failure detection protocol packets
US8271859B2 (en) * 2007-07-18 2012-09-18 Foundry Networks Llc Segmented CRC design in high speed networks
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US9564988B2 (en) * 2007-07-26 2017-02-07 The Directv Group, Inc. Method and system for forming a formatted content stream and using a cyclic redundancy check
US8964734B2 (en) * 2007-07-26 2015-02-24 The Directv Group, Inc. Method and system for communicating content having modified packet headers through a satellite
US8509236B2 (en) 2007-09-26 2013-08-13 Foundry Networks, Llc Techniques for selecting paths and/or trunk ports for forwarding traffic flows
US8090901B2 (en) 2009-05-14 2012-01-03 Brocade Communications Systems, Inc. TCAM management approach that minimize movements
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US3614328A (en) * 1969-06-24 1971-10-19 Kenneth Eugene Mcnaughton Automatic subscriber answering service

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2140940A (en) * 1980-02-19 1984-12-05 Omron Tateisi Electronics Co Data communication control system
GB2140941A (en) * 1980-02-19 1984-12-05 Omron Tateisi Electronics Co Data communication control system
US4639889A (en) * 1980-02-19 1987-01-27 Omron Tateisi Electronics Company System for controlling communication between a main control assembly and programmable terminal units

Also Published As

Publication number Publication date Type
US3866175A (en) 1975-02-11 grant
DE2517831A1 (en) 1975-10-30 application
DE2517831B2 (en) 1977-09-29 application
DE2517831C3 (en) 1978-05-24 grant

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Legal Events

Date Code Title Description
PS Patent sealed
746 Register noted 'licences of right' (sect. 46/1977)
PCNP Patent ceased through non-payment of renewal fee