NCERT Computer: Chapter 5 – Data Communication and Networking Part 1

Introduction

Now a user sitting at one place can communicate with computers of any remote site through communication channel. The aim of this lesson is to introduce you the various aspects of computer network. Computer is available in many offices and homes and therefore there is a need to share data and programs among various computers.

Objectives

  • Identify different types of network

  • Appreciate the use of satellite communication

  • Explain the use of computer network

  • Learn the basic elements of data communication system

Data Communication

Data communications (DC) is the process of using computing and communication technologies to transfer data from one place to another, and vice versa. It enables the movement of electronic or digital data between two or more nodes, regardless of geographical location, technological medium or data contents.

If PCs are connected through communication channel, the data and information, computer files and any other programs can be transmitted to other computer systems within seconds. The modern form of communication like e-mail and Internet is possible only because of computer networking.

Basic Elements of a Communication System

The following are the basic requirements for working of a communication system.

1. The sender (source) who creates the message to be transmitted

2. A medium that carries the message

3. The receiver (sink) who receives the message

In data communication four basic terms are frequently used.

Communication Protocols

A communication protocol is a system of rules that allow two or more entities of a communications system to transmit information via any kind of variation of a physical quantity.

1. Data Sequencing: A long message to be transmitted is broken into smaller packets of fixed size for error free data transmission.

2. Data Routing: It is the process of finding the most efficient route between source and destination before sending the data.

3. Flow control: All machines are not equally efficient in terms of speed. Hence the flow control regulates the process of sending data between fast sender and slow receiver.

4. Error Control: Error detecting and recovering is the one of the main functions of communication software. It ensures that data are transmitted without any error.

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