Wednesday, September 10, 2008

ICT F4 - 3.1.1 : Network & Communication - Define computer networks.


A computer network is a system of interconnected computers and peripheral devices. For example, it may connect computers, printers, scanners and cameras.

Using hardware and software, these interconnected computing devices can communicate with each other through defined rules of data communications. In a network, computers can exchange and share information and resources.

A computer network may operate on wired connections or wireless connections.

When two or more networks are linked or connected and are able to communicate with one another using suitable hardware and software, it is called an internetwork. - Define communications.


Communications is about the transfer of information from a sender, across a distance, to a receiver.

Using electricity, radio waves or light, information and data in the form of codes are transmitted through a physical medium such as wire, cable, or even the atmosphere.

The information that is transmitted (sent) can be text, voice, sound, video, graphics and images, or a combination of all these, which we call multimedia.

We transmit information or data by using two types of signals, namely analog and digital.

Computers communicate with digital signals. The older forms of communications technology, such as telephones and radios, use analog signals.

Therefore, in order to make communications possible from computers, across telephones and radios and back to computers and other digital devices again, there must be a signal translator, which we call – a modem.

The modem, which is short for modulator or demodulator,

converts digital signals into analog and back again into digital signals for information to move across the telephone line.


Communications among computing devices in a network can only happen through defined rules of communications and connections. In general, for communications in a network to be possible, there must be:

* a physical medium – to allow data to travel across it from device to device

* a set of rules called protocols to ensure that interconnected computing devices have the same standards for exchange of information to occur smoothly.

* a system application for managing network information flow to ensure that data transmission sent from one device is received by the intended receiver.

If any of these levels of connectivity is missing, communications for networking will not be possible.

For example, if the physical medium is cut off, there will be no communications.

If protocol between interconnected devices are not the same, data transmission will not be ‘understood’ between devices. If there is no network management application available, there will be no means of ensuring that information from one device will be sent to the correct receiving device.

Protocol Often simply referred to as a protocol, a communications protocol is a set of rules or standards designed so that computers can exchange information with a minimal errors.


In order for a network to properly operate, two categories of network

communications components are needed; ‘Hardware’ and ‘Software’.

Computers, hub, switch, router, network interface cards and both

wired and wireless communications media fall under the ‘Hardware’


Operating systems and applications fall under the ‘Software’ category.


Signals which carry information in a communications system travel through a physical medium.

This physical medium is called a communications channel, or at

other times a communications link, a communications line, or a communications medium.

Some common types of network communications channels are the:

* twisted-pair wire

* coaxial cable

* fiber-optic cable

* satelite systems

* wireless systems (namely using radiowaves, microwaves and infrared)


The Network Interface Card or NIC is one of the most important communications devices for a PC.

The NIC provides connection between the computer and the

network’s communications media.

This connection is necessary because the NIC functions as a data conversion device to move data from the PC’s system to the network medium and vice versa.

The Network Interface Card also supplies the basic addressing system used to get data from PC to PC across a network.

The other hardware component that is required for communications to work on a network is the networking device, such as the hub, switch, router and even the modem.

The function of these devices is generally to control the flow of data on a network.


How do computers communicate on a network?

Once we have got the necessary hardware set up for a network, we will need to have suitable software on the network computers that would be able to provide some basic functions, such as connecting to other computers on the network, sharing resources and files and providing for network security for users who are online.

In general, a network software must be able to handle networking protocols and connections within the network and with other networks. Most importantly, it should also provide file systems functions to organise disk space on the network computers for sharing purposes.

Since most computer networks are connected to the Internet, a network software must have some form of management and security services to protect the network as well as computers on the network, from unauthorised access.


Networking and communications technology is fast changing the way people view society and how we plan our daily social activities.

Through networking technology alone, many today are finding friends online, visiting a library in another country. Some people are able to go to the banks after they are closed, as well as getting the latest development in news from within and outside the country.

Mobile communications today is also based on the networking technology. Surfing the internet is not only limited to the desktop computer users but also those who have mobile phones with wireless technology. At present there are more than 7 million such users across the world.

The internet has helped science and medical research progress further as doctors and researchers from anywhere in the world can contribute and cooperate in any problem brought to their attention. Technological solutions can be discovered quickly as individuals come forward to offer their help through the internet.

Homemakers, students, teachers, business people, and almost anyone with access to networked computer go online and continue their path of lifelong education anywhere, anytime.

Organisations and individuals can make connections and establish communications within seconds with people nearby or overseas. Online communities can be formed and important issues and opinions to difficult problems can be discussed without a threatening environment.

All these are now possible because of networks and communications technology.


Information is now made easy with the availability of network communications.

In a clinic for example, network communications plays an important part in keeping patients’ database for easy retrieval. Unlike in conventional practice, doctors and nurses have to look for a patient’s personal file from hundreds or maybe thousands of records. With network communication, the clinic saves time and manpower allocation can be effectively planned.


E-business or electronic business refers to conducting business transactions on the internet, not only limited to buying and selling but also servicing customers and collaborating with business partners.

E-business supports many types of business transactions, including online shopping, selling and renting. Users can browse the website and choose from the list of items or services to buy. Payment is usually via credit card.

Online Education

With a network connections, online education is made possible. Students at any location around the world can participate in an online classroom, download tutorial questions and submit their assignments.


E-banking or electronic banking is the most popular banking facility nowadays. It handles all types of banking transactions like account management, fund transfer and payments primarily over the internet.

User can pay bills, check the account balance and transfer money to other parties, using e-banking facilities twenty four hours a day and seven days a week.

With e-banking, most of the transactions can be done at home or from the office, thus users save time on traveling and queuing at the bank counters.

Long Distance Communication

Long distance communication is made easy via network availability. Communication is possible via voice, text or video. The cost of having this type of communication is cheaper than making a normal phone call and definitely faster and more effective than corresponding via letters of fax.

In business, important decisions can effectively made through video conference meeting.