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Systems Reference Library

IBM 2740 Communication Terminal Models 1 and 2

Component Description

This publication d escribes 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. Included is a g lo ssary of communi

cation term s used in this publication, and the timing form ulas
n ecessary to calculate the data-handling capability of the term inal.

Summary of Contents for 2740-1

Page 1: ...ne control signals and special features of the IBM 2740 Communication Terminal Models 1 and 2 The communication facilities and data sets that can be used with this Tele processing term inal are also discussed Included is a glossary of communi cation term s used in this publication and the timing formulas necessary to calculate the data handling capability of the terminal ...

Page 2: ... SRL publication IBM 2740 2741 Communications Terminal Operator s Guide Form A 27 3001 For information on other IBM Tele processing products see IBM Tele processing Bibliography Form A 24 3089 Significant changes or additions to the specifications contained in this publication are continually being made When using this publication in connection with the operation of IBM equipment check the latest ...

Page 3: ...Capability Model 1 24 Terminal Transmission and Control Speed 24 Addressing T i m e 24 Polling Time Negative Answer B a c k 24 Polling Time Positive Answer B a c k 24 Checking Time Receive Terminal Positive Answer Back 24 Checking Time Receive Terminal Negative Answer Back 24 Checking Time Transmit Terminal Positive Answer Back 24 Checking Time Transmit Terminal Negative Answer B a c k 24 IBM 2740...

Page 4: ...Auto Check and Transmit Control Switches Figure 1 IBM 2740 Communication Terminal Model 1 s iv ...

Page 5: ...nviron ments see code charts in Appendix Typamatic Index Key Pressing and releasing this key moves the paper up one line space Pressing and holding this key down brings about the typamatic action which causes the paper to rapidly line space until the key is released Interchangeable Print Elements The print elements available for the 2740 Model 1 PTTC BCD and PTTC EBCD and Correspondence are easily...

Page 6: ... Selectric type writer features combined with easily accessible communication controls Figure 2 The IBM 2740 Communication Terminal Model 1 can be specified for any one of three types of opera tions point to point between two terminals or terminal and multiplexer dial up between two ter minals or terminal and multiplexer over a switched network or station control when two or more ter minals and a ...

Page 7: ...a memorandum copy for depart mental distribution as well as a running log of all received messages for future reference Remote Inquiry and Reply with a Computer Using this terminal individuals having access to a CPU Central Processing Unit can accomplish inquiry and reply type operations without leaving their department area For instance an engineer using a 2740 can enter desired variables into a ...

Page 8: ...cipline is required on the communication line This discipline is called line control and one of its functions is to prevent two or more stations from attempting to use the line simul taneously line contention The line control signals EOA EOT EOB Yes No SOA and Inquiry are represented in a short hand form N D and d respectively This form is used in programming as well as in communications and line ...

Page 9: ...d Trade machines SOA Comma character This is used to indi cate a start of address condition and is used when the station control feature is installed d Positive Answer Inquiry Pound sign charac ter This signal is used in a multiplexer operation as a positive answer to an EOB LRC sequence from the terminal Figures 11 and 15 At this time the terminal switches to a receive status The character associ...

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Page 11: ...nal transmits the answerback to an EOB LRC sequence when the Checking special feature is in stalled Receive R Light This light Figure 3 is on when your terminal is ready to receive a character from another terminal on the line or from a multiplexer in the communi cations system During this time your terminal can receive characters only from the terminal or multiplexer which initiated the call and ...

Page 12: ...and an alarm sounds to notify you that transmission can begin from your terminal see Station Control under Special Features Model 1 Restart RST Key and Light Checking Special Feature The Restart light is located to the right of the Re start key Figure 3 When in transmit status the Restart light at your terminal turns on when you perform a checking sequence press EOB key and remains on if the messa...

Page 13: ...itions of the switch are Term terminal Mplx multi plexer and Off Set the switch to Term when transmitting to another terminal and to Mplx when transmitting to a multiplexer With the switch set to Term or Mplx each operation of the Return key causes the carrier to return and the EOB LRC se quence to be transmitted automatically thereby causing the line of characters just transmitted to be checked a...

Page 14: ...proper line control sig nals for the trans mit control feature when operating between a 2740 and a multiplexer With this switch set to the MTC position and in control receive mode the terminal shifts to transmit status when the multi plexer transmits a special two character code space The Off position of this switch places the trans mit control feature in an inactive status See Transmit Control un...

Page 15: ...ine or privately owned line between two 2740 terminals or a 2740 terminal and a multiplexer However the computer program must be designed to handle the basic line control signals used with this type of operation Bid character B and End of Trans mission EOT 5 Refer to Line Control Signals in this manual for a complete explanation of all signals These two line control signals also permit a broadcast...

Page 16: ...paper present in the typewriter Receipt of the B signal switches this terminal to receive status Receive light on keyboard locked and motor turned on The terminal re mains in this status until an EOT signal is re ceived see Figures 5 and 6 However if this terminal runs out of paper while receiving or drops status for any other reason it switches to a no status condition all status lights off key b...

Page 17: ...he ter minal is permanently assigned The dial up line connection is dropped by use of the Dial Disconnect key at one of the terminals or if the status is lost With the automatic disconnect feature supplied by the common carrier when the data set is installed or by a 2740 Model 1 special feature on IBM World Trade machines operating this Dial Disconnect key at one terminal disconnects both ends of ...

Page 18: ...int Opera tion Terminal to Terminal in this section of the manual Transmit Press the Bid key This transmits a 3 signal to the multiplexer Figures 5 and 6 This signal causes the multiplexer to automatically switch to a receive status Once the terminal acquires the line through use of the Bid key it automatically switches to a transmit status In conjunction with this the transmit light is turned on ...

Page 19: ...ess Data button on terminal data set and place receiver in cradle The Dial Connect light will be on indicating the line is connected and the terminal is in a standby status From this point on the operation of the terminal is the same as a terminal to multiplexer operation without the dial up feature see Point to Point Operation Multiplexer and Terminal in this section of manual and Figures 5 and 6...

Page 20: ...ction of the manual and also 2740 Termi nal and Multiplexer with Transmit Control Feature Installed in the IBM 2740 2741 Communication Terminal Operators Guide Form A27 3001 Station Control Multiplexer Addressing and Polling See Station Control under Special Features Model 1 in this section of the manual and also 2740 Termi nals and Multiplexer Station Control Special Fea ture Installed in the IBM...

Page 21: ...n until the Dial Disconnect key is pressed at one of the two terminals or until one of the terminals loses status see Figures 8 and 9 If a line con nection is established between a terminal and a multiplexer the multiplexer also has the ability to disconnect the line Any dialed terminal with this feature installed is prevented from answering if an out of paper con dition exists the terminal is in ...

Page 22: ...Control switch MTC OFF located on the left side of the 2740 cabinet see Figure 1 This switch permits the operator to set up the terminal for proper line control when communicating with a multiplexer MTC using the transmit control code space The OFF position inhibits the terminal from recogni zing the two character control code The 15 second time out is still active in this case if the terminal is ...

Page 23: ...e pressed before transmission can continue The EOT key can also be used to recover from the error condition Operating the EOT key causes the transmitting terminal to send a which places both terminals in standby status LRC During transmission each terminal transmitting and receiving records the bit structure of each char acter The LRC counter at each terminal is started by the transmission of an E...

Page 24: ... by the customer and wired by IBM personnel at installation time This character assignment is always followed by the Space Character to form a two character polling or addressing sequence which permits each 2740 ter minal sharing a specific communication line to recog nize its unique station identification When this recognition occurs the terminal participates in either a polling operation transmi...

Page 25: ...ues If however an error is detected in this message block a hyphen is printed below the message block just completed receiving 2740 terminal only and a negative answer n is returned to the transmitting terminal This N signal causes a hyphen to print below the message block just completed at the trans mitting terminal The n signal also locks the key board at the transmitting terminal turns on the R...

Page 26: ...up to 8 0 miles in length IBM Line Adapter Leased Line This feature permits the customer to attach an IBM 2740 Terminal to a leased common carrier private line or equivalent privately owned facility This line adapter feature installed within the 2740 provides the necessary signal modulation and demodulation for transmission on a communication line without length restriction IBM Line Adapter Shared...

Page 27: ...d the line con nection is lost the terminal returns to standby status If the Dial Up feature is used and the terminal has the Transmit Control feature in stalled loss of the line connection for a period of 15 seconds causes the terminal to disconnect from the line and no code is transmitted Delay Conditions When power is initially turned on the terminal requires a delay of 0 53 to 3 09 seconds in ...

Page 28: ...sponse sample data set turn around time This does not include any delays at multiplexer such as between response and 3 Polling Time Negative Answer Back The time required for a polling operation with nega tive answer back 600 ms is calculated as follows 4 x 67 5 330 600 ms 4 x 67 5 4 character times c address space and n response 330 Delay before transmission of response Checking Time Receive Term...

Page 29: ... negative re sponse before switching to the transmit text lock mode NOTE 270 ms does not include the tim e the receiving terminal requires to respond with the signal after receiving the LRC This figure may vary depending upon the type of data set used and how it is connected Special Features Model 1 25 ...

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Page 31: ...to terminal The line control signals used by the IBM 2740 Model 2 are identical to those used for the Model 1 and the opera tion of the Model 2 is basically the same as the operation of Model 1 The IBM 2740 Model 2 is designed to be used in a wide variety of applications such as payment entry journal entry inquiries administrative mes sages file updating and renewals The terminal can also be used ...

Page 32: ...p at the term inal Non code sensitive regenerators must also be used on the channel Data Sets The IBM 2740 Model 2 operates over communication facilities using the following data sets or their equiva lent Western Electric Data Set 103F2 for use in multipoint or point to point leased private line telephone service Western Electric Data Set 202D1 for use in multipoint or point to point leased privat...

Page 33: ...2 is designed to operate pri marily with an IBM System 360 on a multipoint basis the use of the PTTC EBCD code with its associated keyboard arrangement and print element containing System 360 graphics is recommended see Code Charts and Keyboard Arrangements in Appendix The PTTC BCD code and the Corres pondence code with their associated print elements and keyboard arrangements can be requested on ...

Page 34: ... the EOB or EOT character The contents of the buffer will not be printed during transmission since print ing occurred as the buffer was loaded When opera ting in local mode each operation of the Bid key causes the contents of the buffer keyed in while in local enter mode to print out Reset Key When operating in enter status and com municate mode pressing the Reset key resets the buffer to its firs...

Page 35: ...t only remains on If the Record Checking feature is installed the Reset light will also be on at the completion of the test NOTE If a failure occurs during the test both the Transmit and Receive lights remain on The Parity light will also be on if the type of error detected is a parity error At completion of test set Test switch to Off position If the Reset light is on set local communicate switch...

Page 36: ...perator that the buffer is nearly filled 120 248 or 440 positions The Enter light is adjacent to the Enter key Bid Light The Bid light Figure 20 turns on when the Bid key is operated indicating that the message in the buffer is ready to be transmitted whenever the terminal is polled by the CPU The light turns off when the terminal is polled and transmission begins The Bid light is adjacent to the ...

Page 37: ...Reset light turns on and printout continues Reset key turns Reset light off è Overflow of receive buffer garbled message printed Reset light turns on at time of over flow and turns off automatically when 5 EOT code is received at completion of message Parity error detected when transmitting Reset and Parity lights turn on when error is detected Reset key turns Reset light off and Parity Reset swit...

Page 38: ...Reset key No answerback to 5 LRC sequence Reset light turns on and remains on Reset light can be turned off only by switching the local communicate switch to local and operating the Reset key With Record Checking and With Buffered Receive Special Features Installed Parity error received in receive buffer Reset light turns on and no printout occurs Reset light turns off automatically when answerbac...

Page 39: ...ey The message stored in the buffer is transmitted after the Bid key is opera ted when the terminal is polled by the CPU see Figure 22 If addressed after the Bid key is oper ated the terminal responds with a n negative response and turns on the Attention light and audible alarm A 5 EOT signal is included automatically at the end of message transmission if the terminal does not have the Record Chec...

Page 40: ...ecified by the customer and wired by IBM personnel at installation time Polling The polling sequence is an identification code followed by the Space character The terminal responds with a n if it is not ready to transmit data and a followed by text if it is ready to transmit Figures 22 and 24 Addressing Each 2740 Model 2 terminal can be addressed by three different means an Individual address a Gr...

Page 41: ...sing Bid key only Term Enter Key Bid Key D Text B q Text Enter Key Bid Key D Text Enter K e y Bid Key o T e x t T NON SWITCHED LINE Text In Buffer 1 1 Text In Buffer 0 or 2 Text In Buffer 2 or 3 Mult V 1 M Term Polled Term Polled t Predetermined Number of Retransmissions and Message Still Incorrect V Term Polled V Term Polled ö B E o W R O c ...

Page 42: ...Installed Term Start Buffer Printout Start Buffer Printout NON SWITCHED LINE Mult Term o Text T c Term Term D T e x t l Addressed 1 Addressed Addressed The is a negative answerback in this case The contents of the buffer will not be printed Text IT p C Term 2 W K Addressed y x t r w c ...

Page 43: ...tive response a or a c EOT response is received from the CPU A EOT response indicates the CPU has not received the message correctly and continues to be retransmitted until a positive response a or a EOT response is received from the CPU A EOT response indicates the CPU has not received the message correctly and wants to ter minate the transmission Upon receipt of the code the terminal switches to...

Page 44: ... print This condi tion is not detectable at the CPU and results in lost message blocks at the receiving terminal Telegraph Line Adapter This feature provides an adapter that enables the IBM 2740 Model 2 to be used with a 75 bps leased private line telegraph service With this feature the terminal can operate over leased common carrier or equivalent privately owned 75 bps tele graph channels When us...

Page 45: ...e Line Type key operation This causes the con tents of the buffer to be printed If the message is correct switch to communicate mode and press the Bid key Transmission will occur when the terminal is polled Split Friction Feed Platen A Split Friction Feed Platen is available to further enhance the forms handling capability of the IBM 2740 Model 2 terminal This feature can only be in stalled at the...

Page 46: ...e Margin Stop lever to the rear and moving it either to the left or right to the desired location Therefore the initial operation of a line message printout must begin with an HT Horizontal Tab code to move the carrier a minimum of 23 print posi tions to the right The same line message printout should conclude with an NL New Line Carrier Return and Line Feed code to return the print ele ment to it...

Page 47: ...an be either numerals or alphabetic characters 6 inch or lines identified by numerals or alphabetic charac ters 7 3 8 inch The print line indicators are printed commercially on the document and are a part of the document design specifications provided by the customer Document Alignment 6 Inch Width When using 6 inch documents the first operator print line indicator upper A in Figure 27 should be p...

Page 48: ...ypewriter It also serves as a guide for the paper after printing has been completed A tear bar provides for tearing off printed matter Pin Feed Platens Pin feed platens are available in the following inch sizes for the IBM 2740 Communication Terminal Model 2 Selectric Typewriter Any one of these platens may be ordered in place of the standard friction feed platen NOTE Pin Feed platens cannot be us...

Page 49: ...or leased common carrier private line channels The line adapter feature installed within the 2740 provides the necessary signal modulation and demodulation for transmission on two wire communications lines up to 8 0 miles in length IBM Line Adapter Leased Line This feature permits the customer to attach an IBM 2740 Terminal Model 2 co a leased common carrier private line or equivalent privately ow...

Page 50: ...d have no effect on the formula since the Speed Base feature requires the Buffered Receive feature as a prerequisite To compute the number of idle codes required when operating at 8 33 characters per second Tele graph Line Adapter special feature installed divide the results of N in the formula as shown by 1 7 and round off to the next whole number If the Buffered Receive special feature is instal...

Page 51: ...of the various terminals Master Terminal A remote terminal on a multi point line which is designated to perform all addressing or checking answer back functions for a group of terminals Modulation The conversion of signals from a bus iness machine to frequency signals for transmission over communications lines Multiplexer A device for collecting the input from many communications lines and transfe...

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Page 53: ...APPENDIX This Appendix includes the code charts keyboards used with the 2740 Communication Terminal and graphics involved for the three types of codes Appendix 49 ...

Page 54: ... 2 1 V w B C 8 2 1 w X A C 1 X y B A C 8 Y z C ____8__ 7 z THE CODES BELOW ARE NOT PRINTABLE FUNCTION CODES MEANING PN C 8 4 Punch On BY A 8 4 Bypass RES B 8 4 Restore PF B A C 8 4 Punch Off RS 8 4 1 Reader Stop LF A C 8 4 1 Line Feed NL B C 8 4 1 New Line Carrier Return and Line Feed HT B A 8 4 1 Horizontal Tab UC 8 4 2 Upper Case EOB A C 8 4 2 End of Block BS B c 8 4 2 Backspace LC B A 8 4 2 Low...

Page 55: ... B 8 1 R s A c 2 S t A 2 1 T u A c 4 U V A 4 1 V w A 4 2 w X A c 4 2 1 X y A c 8 Y z A 8 1 z THE CODES BELOW ARE NOT PRINTABLE FUNCTION CODES MEANING PN c 8 4 Punch On BY A 8 4 Bypass RES B 8 4 Restore PF B A c 8 4 Punch Off RS 8 4 1 Reader Stop LF A c 8 4 1 Line Feed NL B c 8 4 1 New Line Carrier Return and Line Feed HT B A 8 4 1 Horizontal Tab UC 8 4 2 Upper Case EOB A c 8 4 2 End of Block BS B ...

Page 56: ...8 1 R s A c 2 S t A 2 1 T u A c 4 U V A 4 1 V w A 4 2 w X A c 4 2 1 X y A c 8 Y z A 8 1 z THE CODES BELOW ARE NOT PRINTABLE FUNCTION CODES MEANING PN c 8 4 Punch On BY A 8 4 Bypass RES B 8 4 Restore PF B A c 8 4 Punch Off RS 8 4 1 Reader Stop LF A c 8 4 1 Line Feed NL B c 8 4 1 New Line Carrier Return and Line Feed HT B A 8 4 1 Horizontal Tab UC 8 4 2 Upper Case EOB A c 8 4 2 End of Block BS B c 8...

Page 57: ...CD and PTTC EBCD print elements and associated keyboards This keyboard and print element is available only on an RPQ Request Price Quotation basis for Model 2 Keyboard PTTC BCD NOTE This keyboard and print element is available only on an RPQ Request Price Quotation basis for Model 2 MAR I BACK REL 1 2 3 4 5 1 6 7 8 9 0 SPACE CLR SET TAB Q W E R T Y U I I I O P LOCK A S D F 1 H J K L I I RETURN SHI...

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Page 59: ...e Signal 4 Paper Guide Tear Bar and Roll Paper Holder 23 Pin Feed Platens 22 Point to Point Operation 3 7 Point to Point Operation Multiplexer and Terminal 14 Point to Point Operation Multiplexer and Terminal with Dial Up Feature Installed 15 Point to Point Operation Terminal to Terminal 11 Polling Time Negative Answerback 24 Polling Time Positive Answerback 24 Pfinciples of Operation 11 Receive O...

Page 60: ...e 2 45 IBM line Adapter Shared Line 45 Indicator Lights 31 Introduction 27 Keys 29 Ledger Card Stock 43 line Return Key 30 41 Line Type Key 30 41 Local Mode 28 35 On Off Power Switch 29 Paper Guide Tear Bar and Roll Paper Holder 44 Parity light 32 Parity Switch 30 Pin Feed Platens 44 Platen Split Light 32 Polling 36 Principles of Operation 35 Print Back Local Mode 28 Receive Light 32 Receive Statu...

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Page 62: ...iness 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 IBM 2740 Printed in U S A A24 3403 3 ...

Page 63: ...ased on your own experience rate this publication As a reference source Very Good Fair Good Poor Very Poor As a text Very Good Fair Good Poor Very Poor What is your occupation We would appreciate your other comments please give specific page and line references where appropriate If you wish a reply be sure to include your name and address Thank you for your cooperation No postage necessary if mail...

Page 64: ... material All com ments and suggestions become the property of 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 Fold I ______ i FIRST CLASS PERMIT NO 155 RALEIGH N C B U S I N E S S R E P L Y M A I L NO POSTAGE NECESSARY IF MAILED IN THE UNITED STATES P...

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