Technical Aspects of Data Communication

Technical Aspects of Data Communication

3rd Edition - January 1, 1988

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  • Author: John E. McNamara
  • eBook ISBN: 9781483184005

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Technical Aspects of Data Communication, Third Edition provides information pertinent to the technical aspects of data communication. This book discusses a simple asynchronous interface implemented with a specialized integrated circuit called a UART. Organized into 28 chapters, this edition begins with an overview of the interface standards ranging from the classic EIA-232-D to the EIA-530. This text then describes modems and modem control, with material on high-speed modems and error-correcting modems. Other chapters discuss hardware and software methods. This book discusses as well digital transmission systems and the Integrated Service Digital Network (ISDN). The final chapter deals with local area networks (LANs) and shows how data communication is the key to information and resources sharing in modern networks of personal computers and work stations. This book is intended to be suitable for readers who are about to design a data communication system, are about to purchase a program data communication hardware, or are just interested in learning more about data communication.

Table of Contents

  • 1. Asynchronous Communications

    Parallel Transmission

    Serial Transmission


    START Bit and STOP Bits

    Achieving Synchronism

    Character Length

    Figures Shift and Letters Shift

    Baudot and ASCII

    A Simplified Asynchronous Receiver

    Single Buffering and Double Buffering

    Overrun Errors

    Framing Errors

    A Simplified Asynchronous Transmitter

    Caution Concerning Double-Buffered Transmitters

    2. A Single Line Asynchronous UART

    General Characteristics of a UART

    Block Diagram of a UART

    Level Converters

    Bit Assignments for Registers in a UART and their Function

    Break Signals

    Programming a UART

    3. Interface Standards

    How the Need for Standards Arose



    Condensed Version of EIA-232-D

    Complete CCITT V.28

    Mark and Space Distortion

    Ground Potential Differences

    Condensed Versions of EIA-422-A, EIA-423-A, and EIA-530

    4. Beyond Interface Standards

    Performance Comparison of EIA-232-D, EIA-423-A, EIA-422-A

    Fiber Optic Fundamentals

    Line Drivers

    Private Lines

    2-Wire Versus 4-Wire

    300 Bps and 1200 Bps Private Line Modems

    5. Private Line Modem Control

    List of Interface Circuits Required for Private Line Modems

    Comparison of EIA-232-D and CCITT V.24 Definitions

    Comments on Clear to Send and Carrier Detect

    6. A Single Line Asynchronous UART with Private Line Modem Control

    Expansion of the Chapter 2 Block Diagram

    Adding Modem Control and Modem Status Bits to the Registers Described in Chapter 2

    7. Asynchronous Multiplexers

    Single Line Asynchronous Interfaces

    Identification of Parts that Could be Shared in a Multiple Line Interface

    Additional Features that Could be Added


    Choice of Line Sizes for Multiplexers

    Pros and Cons of Multiplexers

    8. Telephone Switching Systems

    Historical Development of the Need for Telephone Switching Systems

    Magneto Switchboards


    Common Battery Systems


    Detection of Service Request


    Tone Signaling

    Speed of connection


    Traffic Capacity

    Hunt Groups


    Switched Network Structure

    VNL and SDN Design

    Echo Suppressors

    Network Management

    9. Modem Control for Switched Network Use

    Control Leads Previously Discussed in Chapter 5

    Definitions of Additional Leads for Switched Network Use

    Reason for those Leads Being Required

    Control of Half-Duplex Modems

    Reverse Channels

    Split Speed Modems

    10. Asynchronous Modems for Switched Network Use

    Available Frequency Spectrum

    Details of the 300 Bps ("103-type") Modem

    Originate Mode and Answer Mode

    Eye Patterns

    Carrier Loss Clamps

    A Comparison of Spectrum Utilization by 300 Bps and 1200 bps FSK Modems

    11. Automatic Calling Units


    Condensed Versions of EIA-366 and CCITT V.25 References for Parallel Interface Autodiallers

    Condensed Versions of CCITT V.25 Bis

    AT Command Set

    Vadic VA831, and Digital Equipment DF03-AC References for Serial Interface Autodiallers

    12. Asynchronous Multiplexers with Modem Control

    Programmable Formats and Speeds

    Common Terminal Operating Speeds

    Direct Memory Transfers

    Current Addresses and Byte Counts

    Monitoring and Controlling Modems on 16 Lines

    Transition Detection Systems


    Secondary Registers

    13. Error Detection

    Burst Noise


    VRC and LRC

    Cyclic Redundancy Checks (CRC)

    Methods of Generating CRC

    Why the CRC is Zero for an Error-Free Message

    Mathematical Presentation of CRC

    Generator Polynomials

    Effectivity of CRC

    Step-by-Step Examples of CRC Calculation in Both Hardware and Table-Driven Software

    14. Synchronous Communication

    Efficiency of Synchronous Communication vs. Asynchronous Communication

    Synchronization Search

    Synchronizing on One Character or Two

    Modulation Processes

    Phase Modulation Operation in a 2400 Bps Modem

    Product Modulators

    Demodulation of Phase Modulated Signals

    Operation of 9600 Bit Per Second Modems

    Interface Leads for Synchronous Modems

    Signal Quality Detector and Clock Leads

    15. A Single Line Synchronous USRT

    USRT Chips for Synchronous Interfaces

    Overrun Errors

    Underrun Errors

    Block Diagram and Bit Assignments for a Single Line USRT

    Modem Control Leads for a USRT

    Sync Character Stripping

    Maintenance Features

    Loop Around

    Receiver Blinding for Half-Duplex


    Pad Characters

    Request to Send and Line Turn-Around

    16. Protocols

    Requirement for Protocols

    The ISO Layered Model

    Functions of the Layers

    Existing Types of Protocols

    17. BISYNC and Character Oriented Protocols

    General Format of a Message

    Transparent Text

    Typical Data Exchange

    Definitions of the Special Characters

    Error Checking Codes Used

    Flow Charts of Transmission and Reception

    18. DDCMP and Byte Count Oriented Protocols

    Use of Character Counts for Transparent Transmissions

    General Format of a Message

    Sequencing Messages

    Reply Wait

    Message Classes

    Message Format Detail for Various Classes of Message

    Introduction to the Kermit Protocol

    19. SDLC and Bit Oriented Protocols

    General Format of a Message

    Function of Flags

    Message Fields

    Poll and Final Bits

    Control Field Formats

    Sequencing of Messages

    Definitions of Control Commands and Responses


    20. A Single Line Synchronous USRT for Bit-Oriented Protocols

    Block Diagram

    Register Bit Assignments for Serving BISYNC and DDCMP

    Additional Bits for Serving SDLC

    CRC Error Detection

    Start of Message

    End of Message

    Secondary Station Addressing

    21. Multiplexer Enhancements

    Self-Test Diagnostics

    Receiver FIFO Timer

    Automatic XON/XOFF

    Transmitter FIFOs

    The Need for Intelligent DMA

    Methods of Achieving Intelligent DMA

    Linked Lists

    Ring Buffers

    22. Sophisticated Modems

    List of CCITT Modem Recommendations

    Echo Cancelling

    Trellis Coding

    Error-Correcting Modems

    Microcom Networking Protocol (MNP)

    23. Digital Transmission

    History of Carrier Telephony

    Sampling Theory

    Tl Carrier


    Robbedbit Signalling

    Common Channel Interoffice Signalling (CCIS)

    Clear Channel

    Zero Suppression

    European Systems (CEPT)

    24. Packet Switching

    Comparison with Circuit and Message Switching

    Telecom Canada's Datapac

    Sample X.25 Packet Formats

    25. ISDN


    Bearer Channels

    Data Channels

    Basic Rate Interface

    Primary Rate Interface

    Equipment NT1, NT2, TA, TE1, and TE2

    26. Special Problems

    Connection of Two Pieces of Data Terminal Equipment Via Null Modems

    Clocking of Synchronous Modems and Terminals

    Effect of Clock Skew in Asynchronous Transmission

    Active and Passive 20 Milliampere Devices

    Use of Optical Couplers

    27. CCITT Recommendations X.20 and X.21

    Trends in Quantity of Interface Leads

    Summaries of X.20, X.20 bis, X.21, X.21 Bis

    28. Local Area Networks

    Large Computers Versus Personal Computers

    Sharing File and Printer Services

    Definition of Local Area Network (LAN)

    Star, Ring, and Bus Topologies

    Access Control Via Polling, Tokens, ALOHA, and CSMA/CD


    A. How Far—How Fast?

    Speed Versus Distance Tables for Various Types of Interface Circuits

    B. Modem Options

    A List of Modem Options and their Functions

    C. Codes

    Tables of Baudot, ASCII, and Other Communication Codes

    D. Universal Synchronous Asynchronous Receiver Transmitter (USART)

    Explanation of the USART, Bit Assignments and Signal Functions

    E. Format and Speed Table for Asynchronous Communication

    A List of Character Formats, Character Rates, and Baud Rates for Various Terminals

    F. Channel Conditioning

    Parameters for Private Line Conditioning Offered by AT&T

    G. Interface Connector Pinning

    Pinning Assignment for the 25-Pin D-Subminiature Connector as Used in EIA-232-D and EIA-530

    H. Hayes Smartmodem 1200™ and Hayes Smartmodem 2400™ Dialling Commands and Responses

    An Excerpt from the Quick Reference Cards for These Products Showing the Flexibility and Complexity of Modern Serial Interface Dialling

    I. Where to Get More Information

    A List of Addresses and Telephone Numbers for Obtaining EIA, CCITT, ISO, ANSI, and AT&T Documents



Product details

  • No. of pages: 396
  • Language: English
  • Copyright: © Digital Press 2014
  • Published: January 1, 1988
  • Imprint: Digital Press
  • eBook ISBN: 9781483184005

About the Author

John E. McNamara

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