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IBM 2740-1 System Reference Manual

Communication terminal
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IBM 2740 Communication Terminal Models 1 and 2
Component Description
This publication d escrib es the application a re a s, principles of oper­
ation, lin e-co n tro l signals, and special features of the IBM 2740
Communication Term inal Models 1 and 2.
fa c ilitie s and data sets that can be used with this T ele-p ro cessin g
term in al are also discussed.
cation term s used in this publication, and the timing form ulas
n ecessary to calculate the data-handling capability of the term inal.
The communication
Included is a g lo ssary of communi­

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  • Page 1 IBM 2740 Communication Terminal Models 1 and 2 Component Description This publication d escrib es the application a re a s, principles of oper­ ation, lin e-co n tro l signals, and special features of the IBM 2740 Communication Term inal Models 1 and 2. The communication fa c ilitie s and data sets that can be used with this T ele-p ro cessin g term in al are also discussed.
  • Page 2 . Operating procedures for the IBM 2740 Models 1 and 2 , and the IBM 2 7 4 1 , are described in the SRL publication IBM 2 740/2741 Communications Term inal—...

  • Page 3: Table Of Contents

    A u to m atic EOB (Prerequisite , Checking Feature) Document I n s e r t i o n ..............41 IBM 2760 A t t a c h m e n t ................22 Ledger-Card S t o c k ................43 IBM Line Adapter (Lim ited-D istance Type 1) .
  • Page 4 Auto C h eck Transmit a n d C ontrol Sw itches Figure 1. IBM 2740 Communication Terminal, Model 1...

  • Page 5: Ibm 2740 Communication Terminal, Model 1

    The other element is positioned by snapping it into other 2740 terminal (or terminals) or to a place. computer using an IBM 2701 Data Adapter Unit, an IBM 2702 or 2703 Transmission Control Unit, or an IBM 2712 Remote Multiplexer connected to NOTE: A choice of print elements (PTTC/BCD, PTTC/EBCD, a 2702 or 2703.

  • Page 6: Types Of Operation

    With this cartridge, ribbon changing con­ The IBM 2740 Communication Terminal Model 1 sists of snapping one cartridge off and the new one on. can be specified for any one of three types of opera­...

  • Page 7: Applications

    Several of the many center or mail room. The message is handled only application areas for which the IBM 2740 is designed are: by the executives and their secretaries at the sending and receiving locations.

  • Page 8: Data Sets

    When the 2740 is used on com m on-carrier switched networks, com m on-carrier provided data sets must be used. IBM Line Adapters are avail­ Answer. The negative, positive, or no answer at able for use on com m on-carrier leased private line all to a check (VRC or LRC) following an EOB.
  • Page 9 (a different character the terminal (Figures 11 and 15). At this tim e, is printed on IBM World Trade machines). the terminal switches to a receive status. character associated with this signal is not printed. IBM 2740 Communication Terminal, Model 1...

  • Page 11: Transmission Controls And Indicators, Model 1

    TRANSMISSION CONTROLS AND INDICATORS, MODEL 1 These controls and indicators are located directly Receive (R) Light adjacent to the left and right of the typing keyboard, as shown in Figure 2. They provide additional con­ This light (Figure 3) is on when your terminal is trols required for operating in communicate mode.

  • Page 12: R Estart (Rst) Key And Light (Checking Special Feature)

    Figure 3. IBM 2740 Model 1 Transmission Controls (Right Side of Keyboard) Check-Loop Test R estart (RST) Key and Light (Checking Special Feature) The Bid key is also used to test a portion of the electronic circuitry of the terminal (see nTest Pro­...

  • Page 13: Eob (End-Of-Block) Key (Checking Special Feature)

    (Transmit light turns on, Receive and Re­ Figure 4. IBM 2740 Model 1 Transmission Controls (Left Side of start lights turn off, and keyboard unlocks) and you Keyboard) can continue with message transmission.

  • Page 14: Eot (End-Of-Transmission) Key

    Test switch, labeled Mod (Modem), Line and Off is Control Special Feature used when communication cannot be established with a remote terminal. Refer to IBM 2740 Terminal This switch is located on the left side of the 2740 and Line Adapter Test Procedure under Test Pro­...

  • Page 15: Principles Of Operation, 2740 Model 1

    PRINCIPLES OF OPERATION, 2740 MODEL 1 This section covers the operation of the basic IBM These two line-control signals also permit a 2740 Communication Terminal Model 1, without any broadcast type of operation. In this operation, a special features, and then with special features in­...

  • Page 16: Broadcast Operation

    • Receipt of the signal switches this terminal • P ress the Bid key. This transmits a (§) signal to the other terminal on the line (Figures 5 to receive status (Receive light on, keyboard Upon receipt of the signal, the re ­ locked, and motor turned on).

  • Page 17: Dial-Up Operation

    A facilities employed. Since a dial-up operation different character is printed on IBM World Trade connects the terminal to a line accessible to the machines. Also, at the end of each message block, general public, this line connection must be dropped the total message block is checked by an LRC com­...

  • Page 18: Point-To-Point Operation-Multiplexer And Terminal

    mains locked), the Restart light is turned on, and Transmit the audible alarm sounds at the transmitting term i­ P ress the Bid key. This transmits a signal nal. The Transmit light will remain on. the multiplexer (Figures 5 and 6). This signal The Bid and EOT keys are used the same in this causes the multiplexer to automatically switch to a...

  • Page 19: Point-To-Point Operation-Multiplexer And Terminal With Dial-Up Feature Installed

    When the dial-up feature is used, disconnect is available as a terminal special feature a communication line connection must be established on IBM World Trade machines. before the terminal and multiplexer can communi­ cate with each other (Figures 8 and 9). The...

  • Page 20: Transmit Control-Multiplexer

    2740 Term i­ stalled on the multiplexer data set), or by operating nals and Multiplexer—Station Control Special Fea­ the Dial-Disconnect key at the terminal. ture Installed in the IBM 2740/2741 Communication Terminal—O perators Guide, Form A27-3001. EOT Key Dial...

  • Page 21: Dial-Up Adapter

    Dial-Disc keys is possible only Transmit Control (Prerequisite, Dial-Up Adapter if the comm on-carrier data sets have the auto-disconnect feature installed, o r, in the case of IBM World Trade Feature) machines, the terminal is equipped with the auto-disconnect special feature.

  • Page 22: A U To M Atic Disconnect Feature (World Trade Only)

    An alarm is also turned on at the terminal to alert the operator that the transmission of text can begin. NOTE: This feature cannot be used when an IBM 2760 Optional This feature can be installed only with dial-up line Image Unit is attached to the 2740 terminal.

  • Page 23: Checking- Parity (Vrc) And Block (Lrc)

    The LRC counter at each terminal is started by the transmission of an EOA signal which indi­ NOTE: The feature is a prerequisite when an IBM 2760 Optional Image Unit is attached to the IBM 2740 Communication cates the start of a message.
  • Page 24 Identification Identification identification character is specified by the customer Character Character and wired by IBM personnel at installation time. This character assignment is always followed by the Terminal 1 A Space D Space Space Character to form a two-character polling or...

  • Page 25: Automatic Eob (Prerequisite, Checking Feature)

    answer is returned to the transmitting terminal. In addressing responses for the group. the first instance, normal transm ission continues. A ll-call addressing (transmitting to all stations If, however, an erro r is detected in this message on the line simultaneously) is accomplished by the block, a hyphen is printed below the message block transmission of a special two-character code (/ just completed (receiving 2740 terminal only), and...

  • Page 26: Ibm 2760 Attachment

    Planning and Installation of a D ata Communications 2740 Terminal to customer-installed communication System Using IBM Line A dapters, Form A 2 4 -3 4 3 5 . lines or leased com m on-carrier private line channels The line adapter feature (installed within the 2740) Pin-Feed Platens provides the necessary signal modulation and de­...

  • Page 27: Paper Guide, Tear Bar, And Roll Paper Holder

    Time-Out Conditions * • tion (CR/LF), or a tabulate (tab) operation. The IBM 2740 Communication Terminal Model 1 (1. 5 + T) x 67. 5 = Elapsed time in milliseconds will time out whenever any of the following condi­...

  • Page 28: Data-Handling Capability, Model 1

    DATA-HANDLING CAPABILITY, MODEL 1 START STOP START s t o p ----------------------------------- 6 7 .5 MS ---------------------------- ► IN D ICATES N O 8 BIT A N D N O C BIT To compute the data-handling capability of the 2740 Terminal, Model 1, the following basic timings Figure 16.
  • Page 29 NOTE: 270 ms does not include the tim e the receiving term inal (3 x 67. 5) + 67. 5* = 270 ms requires to respond w ith the signal after receiving the (3 x 67. 5) = 3 character times (( ) , LRC, and LRC.

  • Page 31: Ibm 2740 Communication Terminal, Model 2

    Model 2 is basically the same as the Document Insertion Feature. operation of Model 1. The IBM 2740 Model 2 is designed to be used in inserted individual form s, such as: ledger cards, a wide variety of applications, such as: payment checks, and single-part form s.

  • Page 32: Communication F A C I L I T I E S

    The IBM 2740 Model 2 is designed for communicating • An appropriate channel termination for use on with an IBM System/360 Model 25, 30, 40, 50, 65, Telephone Company 150 baud (Schedule 1006) 75, or 85 through an IBM 2701 Data Adapter Unit, an IBM 2702 or 2703 Transmission Control Unit, or channels.

  • Page 33: Communicate

    ) EOB key and (c) EOT key have been r e ­ sounds, and a (N) negative-response signal is sent moved from the IBM 2740 Model 2 keyboard, since those signals are provided automatically; however, to the CPU. If the terminal is polled while in enter...

  • Page 34: Switches

    Line Rtn (Return) Key (Special Feature). See Edit feature under Special Features, Model 2. Figure 19. IBM 2740 Model 2 Operator Controls (Left Side of Keyboard) Line Type Key (Special Feature). See Edit feature local or communicate mode.

  • Page 35: Indicator Lights

    Figure 20. IBM 2740 Model 2 Operator Controls (Right Side of Keyboard) whether the terminal or IBM Modem; or the receiv­ NOTE: If a failure occurs during the test, both the Transmit and ing multiplexer, modem, or communications line is Receive lights remain on.
  • Page 36 Figure 21. IBM 2740 Model 2 Switch Panel Bid Light. The Bid light (Figure 20), turns on when Receive Light. The Receive light (Figure 20), when the Bid key is operated indicating that the message in on, indicates the terminal is receiving and printing the buffer is ready to be transmitted whenever the incoming data.

  • Page 37: Without Buffered Receive And Without Record Checking Special Features Installed

    Incorrect character prints, Reset Operating Reset key turns Reset light off, restores light turns on, and printout continues. Reset key the buffer, and terminates the enter operation. turns Reset light off. IBM 2740 Communication Terminal, Model 2...

  • Page 38: With Record Checking And With Buffered Receive Special Features Installed

    printout. Incorrect character is printed, Reset • Incorrect-case code received. Hyphen prints, light turns on, and printout continues. Reset key Reset light turns on and remainder of message turns Reset light off. is printed. Reset light turns off automatically when EOT answerback is sent to CPU.

  • Page 39: Principles Of Operation, Model 2

    PRINCIPLES OF OPERATION, MODEL 2 Local Mode ated, the terminal responds with a ( ) negative When operating in local mode, the information typed response and turns on the Attention light and audible at the keyboard can also enter the buffer provided alarm.

  • Page 40: Station Control (Multiplexer Addressing And Polling)

    A group address consists of the group identifica­ NOTE: Each 2740 master terminal (either group or all call), re­ quires its own local loop when using a 4-w ire IBM leased or tion code, selected at time of installation is followed shared line IBM Line Adapter.
  • Page 41 (1) Operator can enter new data in buffer; or(2) Can send data again by pressing Bid key only. © Enter Enter Enter ^D^Text^B^) ( o ) T e x t ( T ) ^D^Text Text © © K e y Term.
  • Page 42 -Start Buffer Printout -Start Buffer Printout © © © © © , © Term. © ' N O N - SWITCHED LINE Mult. Term Text ( T ) !" Term ( D ) T e x t ( l ) £ Text (IT ) p Term ®...

  • Page 43: Special Features, Model 2

    SPECIAL FEATURES, MODEL 2 Buffer Expansion or a (c) EOT response is received from the CPU. A © EOT response indicates the CPU has The buffer is also available in 248- and 440- posi­ not received the message correctly and continues tion sizes.

  • Page 44: Buffered Receive

    Without the Buffered Receive feature IBM 2740 Model 2 to be used with a 75-bps leased installed, the CPU may respond to the @ with private-line telegraph service. With this feature, the terminal can operate over leased common- another block of text, or a @ EOT code.

  • Page 45: Split Friction-Feed Platen

    A Split Friction-Feed Platen is available to further erase all characters up to and including the first enhance the forms-handling capability of the IBM character of the present line. 2740 Model 2 terminal.
  • Page 46 Figure 26. Document Insertion Feature for printing if the operator replaces the split platen printout must begin with an HT (Horizontal Tab) code with a standard friction-feed platen (see Split to move the carrier a minimum of 23 print posi­ Friction-Feed Platen).

  • Page 47: Ledger-Card Stock

    6 to the inch. The ledger card should be of single-part, 90- to 120 When the document is inserted and the first print- pound stock (IBM card stock meets these specifica­ line indicator (A) is aligned between the two red tions).

  • Page 48: Paper Guide, Tear Bar, And Roll Paper Holder

    IBM 2740 Communication Terminal Model 2 Selectric Typewriter. Any one of these This feature permits the customer to attach an IBM platens may be ordered in place of the standard 2740 Terminal Model 2 to custom er-installed com­...

  • Page 49: Ibm Line Adapter (Limited-Distance Type 2)

    2740) provides the necessary signal modu­ lation and demodulation for transmission on two- This feature permits the customer to attach an IBM wire or four-wire communications lines up to 4. 75 2740 Terminal Model 2 co a leased com m on-carrier miles in length with a single 2740 attached.

  • Page 50: Timing Considerations, Model 2

    N in the formula as shown by 1.7, and facilities. round off to the next whole number. If the Buffered NOTE: For additional information on the use of IBM line adapters, Receive special feature is installed, idle characters see Planning and Installation of a Data Communications are not required after function codes (NL, HT, and System Using IBM Line Adapters, Form A 24-3435.

  • Page 51: Glossary

    GLOSSARY addressing or checking answer-back functions for The following is a listing of the communications term s used in this manual. For a complete listing a group of term inals. of communications term s refer to the manuaLIBM Modulation. The conversion of signals from a bus­ Data Processing Techniques, Data Communications iness machine to frequency signals for transmission Glossary, Form C20-1666.

  • Page 53: Appendix

    APPENDIX This Appendix includes the code charts, keyboards, used with the 2740 Communication Terminal, and graphics involved for the three types of codes Appendix...
  • Page 54 BIT VALUE LOWER CASE UPPER CASE • • ------------ ]---------------- '/□ ¥ & __________ A____________________________________________ ____8__ THE CODES BELOW ARE NOT PRINTABLE FUNCTION CODES M EANING Punch On Bypass Restore Punch Off Reader Stop Line Feed New Line (Carrier Return and Line Feed) Horizontal Tab Upper Case End of Block...
  • Page 55 LOWER CASE UPPER CASE Bit Value CHARACTER SET CHARACTER SET Std.| r ^ r Typ. Std J1 A Typ..ï . § • < & — — ! = □ 1 > & THE CODES BELOW ARE NOT PRINTABLE MEANING FUNCTION CODES Punch On...
  • Page 56 Bit Value LOWER CASE UPPER CASE — , & < > THE CODES BELOW ARE NOT PRINTABLE FUNCTION CODES M EANING Punch On Bypass Restore Punch Off Reader Stop Line Feed New Line (Carrier Return and Line Feed) Horizontal Tab Upper Case End of Block Backspace...

  • Page 57: Index

    — & BACK < INDEX 8 1 1 9 SPACE 11 0 RETURN LO CK O FF SHIFT SHIFT SPACE BAR Keyboard (Standard Selectric Typewriter) NOTE: When this keyboard and associated print elements are specified, the line code assignments of the graphic char ­ acters change and are not compatible with the PTT/BCD and PTTC/EBCD print elements and associated keyboards.
  • Page 59 Transmit Control (Multiplexer) Transmit Operation (Multiplexer and Terminal) IBM line Adapter (Lèased Line) Transmit Operation (Multiplexer and Terminal with Dial-Up IBM Line Adapter (lim ited-D istance Type 1) Feature Installed) IBM Line Adapter (Limited-Distance Typ^ 2) Transmit Operation (Term inal-to-T erm inal)
  • Page 60 Header Switch Split Friction-Feed Platen Standby light IBM Line Adapter (Leased Line) Standby Status IBM Line Adapter (Limited Distance Type 1) Station Control (Multiplexer Addressing and Polling) IBM Line Adapter (Limited Distance Type 2) Switches IBM line Adapter (Shared Line)
  • Page 61 «...
  • Page 62 A24-3403-3 International Business Machines Corporation Data Processing Division 112 East Post Road, White Plains, N.Y. 10G01 [USA Only] IBM World Trade Corporation 821 United Nations Plaza, New York, New York 1ÜG17 [International]...
  • Page 63 READER'S COMMENT FORM 2 7 4 0 u n i c a t i o n e r m o d e l s a n d 2 4 - 3 4 0 3 - 3 • How did you use this publication? □...
  • Page 64 IBM. Please note: Requests for copies of publications and for assistance in using your IBM system should be directed to your IBM representative or to the IBM sales office serving your locality. Fold...

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2740-2

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