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Saturday, November 26, 2011

Differences between LAN and WAN

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The differences between LAN and WAN is as follows:
LAN (Local Area Network)

1.

LAN is used to connect computers at one place, in one room or a building.
2.

LAN covers small and limited area.

3.

Data transfer speed is very fast in LAN because of small distance.

4.
Local Area network speed is normally form 1 to l00 Mbps.
5.

LAN is less costly.

6.

LAN is usually connected through wires.

7.

Normally, the   connection    in    a    LAN    is permanent using wires.

8.

LAN is used for sharing data, information, files and hardware like printers, hard disk, modem etc.

9.

LAN has   less   possibility   of data transmission error.

10.
LAN is used to transfer data over small distances.
11
LAN is easy to install and configure.
12
LAN is easy to troubleshoot.
WAN (Wide Area Network)
1
WAN is used to connect computers anywhere in the world.
2
WAN can cover larger area. It can cover cities, countries and even continents.

3
Data transfer speed is slower in WAN.

4
Transmission     speeds     are     normally 56 kbps to 45 Mbps.
5
The hardware needed for a WAN is more expensive.

6
WAN is usually connected through telephone lines, fiber optic cable or through wireless media.

7
The    connection    in    WAN    may not be permanent.

8
WAN is used to share only data and information like Email and file transfer

9
WAN has more possibility of data transmission error because of long distance.

10
WAN is used to transfer data over long distances.
11
WAN is difficult to install and configure due to connecting computers at multiple and distant sites.
12
WANs are difficult to troubleshoot.
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Friday, November 25, 2011

Types Of Computer Networks

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Explain different types of computer networks:(LAN,WAN,MAN)

Today, we will discuss the main types of computer networks on the basis of the distance over which they operate. The main types of computer networks are:

1.    LAN - Local-Area Network
2.    WAN - Wide-Area Network
3.    MAN - Metropolitan-Area Network

1)LAN (Local Area Network)

What is LAN or Local Area Network

LAN stands for Local Area Network. It covers a small area. Most LANs are used to connect computers in a single building or group of near buildings. Hundreds or thousands of computers may be connected through LAN. LANs are used in office buildings, college or university campus etc. Local Area Networks can transfer data at a very high speed. Data transmission speeds of LAN are 1 to 100 megabits per second.

Examples of Local Area Network

Following are examples of LAN:
  • LAN is used in a computer lab to connect computers. The students can share software, files and data in the lab.
  • In Internet cafe, many computers can be connected through LAN. These computers can share single connection of Internet.
  • Local Area Network can be used in an office to share common data and a network printer and any other software or hardware.
  • A local area network in a digital library can provide access to centralized collection of digital books for many readers using different computers in library building.
2)WAN (Wide Area Network)

What is WAN or Wide Area Network?

WAN stands for wide area network. It covers a large area. WAN connects computers in different cities, countries and continents. So, Wide Area Networks are used to transfer data over very long distances across cities, countries or even in whole world. WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations.
Computers in WAN are often connected through leased lines telephone lines. They can also be connected through satellites. Transmission rate of WAN is 56 kbps to 45 Mbps. WAN is expensive than LAN. WAN is not as fast as LAN. There is a possibility of error in data transmission due to very long distance they cover. The largest WAN  is the Internet. With the help of internet, we can send our data in any part of the world.

Examples of WAN

  • In air line ticketing system, many offices of an air line company can be joined together using WAN. A person can get a ticket from any office in the country.
  • A bank with many branches in different cities can connect its branches through WAN. The customer can use his account from any branch.
3)MAN (Metropolitan-Area Network)


What is MAN or Metropolitan Area Network? 

A metropolitan area network (MAN) is a network that covers an area of the size of a city. So, a MAN is larger than a local area network but it is smaller than a WAN. A MAN is optimized for a larger geographical area than a LAN, ranging from several blocks of buildings to entire cities. MANs can use communications channels of moderate-to-high data transfer rates. It may use fiber Optic cable for fast speeds.
A MAN typically includes one or more LANs but cover a small area than WAN. A MAN often acts as a high-speed network.

Examples of MAN or Metropolitan Area Network:

  • Mobile phones systems often use MAN.
  • Many local ISPs manage MAN with the help of cable modems within a city.
  • Local cable TV networks also uses MAN technologies.

Read  More on Networking
and Networks
1 Explain
Advantages Of Networks
2 Types
Of Computer Networks
3 Differences
between LAN and WAN
4 Types
Of Network Topology
5 Bus
Topology :Advantages and Disadvantages
6 Advantages
and Disadvantages of Star Topology
7 Advantages
and Disadvantages of Ring Network Topology
8 Advantages
and Disadvantages of Tree Topology
9 Advantages
and Disadvantages of Mesh Topology
Read More...

Wednesday, November 23, 2011

Explain Advantages Of Networks

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Define Network with examples. Give importance of Computer Network.

COMPUTER NETWORK

We can define a Computer Network as a set of two or more connected computers to share information and other resources (data, files, printers, hard disk, modem, CD-Rom Drive, CD-Writer, DVD-Rom Drive, DVD-Writer etc.). The computers in a network can share:
Data, Information, Files
Software
Hardware (printers, disk, modems)etc.

EXAMPLES OF COMPUTER NETWORK

  • Computer network can be used in an office. Different people in the office can share common information and printer.
  • Net Cafes use Computer Network for internet sharing. Net Cafe Owners can save money by sharing one DSL Routers / Modem and a single Internet Connection.
  • Computer Network is used in Computer Laboratories of Schools, Colleges and other educational institutes.
  • Internet, is also an example of a computer network. Internet is a network of millions of computers connected through phone lines. People can share information, files and talk with one another through internet.




    ADVANTAGES OF COMPUTER NETWORKS

    Following are some important advantages of computer networks:

    1. Data and Information Sharing

    Different employees of an organization can share common information with the help of computer network.

    2. Software Sharing

    Different software can be shared with the help of computer networks.

    3. Hardware Sharing

    Different hardware can be shared with the help of computer networks. For example, if there are five computer users in an office, we can save cost by using only one printer with the help of computer networking. In a computer network, only one computer will manage all printing needs of the computer users in a small office. In addition, we can share other hard ware devices like hard disks, CD-Rom Drives / Writers, modems, routers and scanners etc.

    4. Money Saving

    We can save a lot of money by using computer networking, because of sharing the same software and hardware in a network.

    5. Internet Sharing

    We can buy only one DSL internet connection and share it with in whole organization with the help of computer networking.

    6. Easy Communication Within Organization

    We can send and receive messages and files through network. In this way, a file can be moved to one place to another within an organization without the need of a physical worker to take and carry the files to a destination. With the help of a command in a computer we can transfer file within seconds from one room to another.

    7. Easy Communication Outside Organization

    We can send and receive emails and share files with other people outside organization using internet.

    Read  More on Networking
    and Networks

    1 Explain
    Advantages Of Networks
    2 Types
    Of Computer Networks
    3 Differences
    between LAN and WAN
    4 Types
    Of Network Topology
    5 Bus
    Topology :Advantages and Disadvantages
    6 Advantages
    and Disadvantages of Star Topology
    7 Advantages
    and Disadvantages of Ring Network Topology
    8 Advantages
    and Disadvantages of Tree Topology
    9 Advantages
    and Disadvantages of Mesh Topology
    Read More...

    Monday, November 21, 2011

    Types Of Scanners Input Device

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    Scanner / Optical Scanner

    A scanner is an input device for computer. It can scan any printed document with text as well as images. It will :
    • Read any printed paper or picture,
    • Convert text or images into digital form
    • Saves this converted digital file into computer storage for later use

    Uses Of Optical Scanners

    You can scan your documents or pictures to:
    1. Store into computer memory.
    2. To save lot of effort and time because if you type the whole text on printed page, it will take effort as well as time).
    3. Show image or text on computer screen or on a multimedia projector's screen.
    4. In addition, you can send this scanned document or image to your friends all over the world with the help of Internet & Email.
    5. You can publish the scanned documents or images on your website or blog.
    6. You can apply online and send the scanned images of your academic documents in any part of the world within minutes.
    7. If your scanner supports OCR - Optical Character Recognition, you can scan a page with printed text and save it in an editable computer file. You can change or add more contents in this scanned file.

    Types Of Optical Scanners

    There are different types of scanners:

    1. Flat Bed Scanner




    A flatbed scanner is the most common type of optical scanners used to scan printed text and images and save into computer storage as a digital file. It works on the principle of a photo copier machine. We pickup the cover of the scanner and place the printed page on the glass surface of the scanner. Now we will instruct scanner through computer software to start scanning. The scanner will scan with the help of light and save the digital file into computer storage. If you have an OCR scanner, you can save your text into editable form. This will save a lot of hard work and time to enter text by keyboard too. It is widely used in offices, schools, colleges, universities and homes for common scanning needs. If a book is very rare or difficult to find, we can scan its all pages one by one. Later on we can take prints of these scanned pages through a color printer.

    2. Sheet Fed Scanner




    A sheet fed scanner works like a fax machine mechanism. In a sheet fed scanner, pages are entered into scanner like a fax machine.

    Advantages of Sheet Fed Scanner

    1. A feet shed scanner is relatively smaller in size.
    2. It is more portable.
    3. It takes less space.

    Disadvantages Of Sheet Fed Scanner

    1. It requires separate pages to scan. But, it cannot scan a book because of its binding. 
    2. It can scan normal papers with normal thickness only. 

    3. Hand Held Scanner




    Hand Held scanner is a small, light weight scanner and portable scanner. It is used to scan small amount of data like short articles from news papers. It is held in hand and is moved over the text page or image slowly and smoothly from start to end. Its scan quality may be lower than flat bed or sheet fed scanner but it can used to capture small amounts of text or small images, quickly.

    SkyPix Hand held Scanner




    This is a portable, cordless hand held scanner that is used to scan and save important documents, letters, or pictures. It records scanned documents in its memory card. you can transfer these scanned documents on yor computer for later use. You can scan and save important news from the news papers or interesting articles from magazines.

    4. Drum Scanners




    Drum scanners are used by the Publishers to scan images with details. Drum scanners use photomultiplier tube technology. In drum scanners, the document to be scanned is mounted on a glass cylinder. At the center of the cylinder is a sensor that splits light bounced from the document into three beams. Each beam is sent through a color filter into a photomultiplier tube where the light is changed into an electrical signal. And in this way a complete image with immense details can be obtained. Drum scanners are widely used in publishing industry.
    Read More...

    Thursday, November 17, 2011

    Uses Of Computer In Science

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    Today, computers are being used in every field of life. Here we discuss Uses of Computers in Science:

    Data Collection

    Scientists use computers to collect data and make hypotheses on the basis of collected data.

    Analysis and Testing Of Data

    Scientists use computers to analyze collected data and test their hypotheses.

    Exchanging Information

    Scientists use computers to exchange information with their colleagues. Different Researches all over the world can share their research with one another. This will be helpful for research because this will increase the rate of completion of research projects.

    Simulation of Different Events

    Scientists may use computers for simulation of complex events. For example, they can use computer simulation to predict about the affects of earthquake on buildings in a particular area. They may use computer simulation to know the effects of rapid population increase on weather conditions. In fact, computer simulation of such complex events will save time as well as cost. Computer simulation can also provide a feasible solution to many problems.

    Use Of Computer in Medical Science

    Computers may also be used to simulate the functions of parts of human body. For example, computers may simulate cell division, internal structure of molecules, a virus or bacteria attack etc.

    Uses of Computer in Space Science

    Computers are playing an important role to explore the outer space. The computers are mostly used to collect space data, perform experiments and prepare results. Computers are used to operate certain machines and robots to collect information from space and send it back on earth.
    Further Suggested Reading:
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    Wednesday, November 16, 2011

    System Software and Application Software:Differences

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    Q. Differentiate between system software and application software

    System Software:

    System software is a set of programs to control all components of computer and to manage overall operations of computer system. System software is used as a base to install and run all application software. Examples of system software include:
    1. Operating Systems, like Microsoft Windows, DOS, Unix and Linux
    2. Device Drivers like Device driver software of a Printer (found on CD normally provided with the printer)
    3. Utility Programs like AVAST anti virus, Disk Scanners and File Viewers etc.

    Differences between system software and application software

      Application Software:

      Users can use Application Software to perform different applications on computer. Application Software generally performs a specific task for a computer user. Examples of Application software include:
      1. Wordprocessors like Microsoft Word
      2. Spreadsheet Software like MS Excel
      3. Database software like Microsoft Access etc.
      Difference between System & Application Software
      System Software

      Application Software

      1. It is a set of programs to control computer components and operations.

      1. It is used to solve particular problems of user.

      2.  It is general-purpose software.

      2. It is specific purpose software.

      3. It executes all the time in computer. Because it controls overall operations and components of computer.

      3. It executes as and when required. For example, if we need to write a letter, we will open Microsoft Word - an application software. And after we have written and printed the letter, we will close Microsoft Word.

      4. The number of system software is less than application software.

      4. The number of application software is much more than system software.

      5. System software is essential for a computer to work. Without System software (like operating systems), a computer is useless. We cannot use computer hardware without system software. That is why we install an operating system first of all, after buying a new computer.

      5. Application software is not essential for a computer to work. For example, if we need to play some games then we buy a game CD or download games from internet, and install in our computer.

      6. Examples are: Windows, Dos, Unix, Linux, Norton Antivirus etc.
      6. Examples are: MS Word, MS Excel, MS Power point etc.
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      Tuesday, November 15, 2011

      Customized and Packaged Software

      4 comments

       

      Q. Explain Customized software and Packaged software.

      a) Customized Software




      Customized software is a type of application software that is designed for a particular customer or organization. When packaged software does not fulfill needs of an organization then a programmer / software developer / software engineer is hired. The programmer will develop needed custom software for that organization according to the organizations specific needs and requirements.
      Student Information software developed for Govt. Post Graduate College of Commerce, Rahim Yar Khan is an example of customized software.  It will be used to store all related data about students, admissions and examinations etc.

      b) Packaged Software




      Packaged software is a type of application software that is developed for sale to the general public. It is also known as off-the-shelf software or Pre-Written software. It facilitates the people to perform day-to-day activities. Examples of packaged software are word processing software and spread sheet software.
      For example, Microsoft Office is a packaged software. Microsoft Office is a set of different application software like Microsoft Word, Microsoft Excel, Microsoft Access and Microsoft Power Point.
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      Sunday, November 6, 2011

      Define Web Server, Web Browser, WWW, ISP

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      Q. Write notes on the following:
      WWW, ISP, WEB PAGE, WEB SITE, WEB SERVER, WEB BROWSER



      WWW

      WWW stands for World Wide Web. It is also called web. It is the collection of all connected web documents stored on different web servers. These documents contain information in the form of text, pictures, audio and video clips. WWW has many advantages:
      · finding a job
      · searching information
      · advertisement for business
      · weather forecast
      · entertainment
      · education

      Difference between Internet and World wide web:


      The main difference between internet and World Wide web is that World Wide Web is only a service provided by internet. It provides access to web documents. While internet provides many other services also like FTP, TELNET and chatting etc.

      ISP (Internet Service Provider) OR IAP (Internet Access Provider

      ISP stands for internet service provider. It is a company that provides internet connections to users. For example WOL net, PAK net, CYBER net etc. are ISPs. To connect to internet, users have to get internet connection from an ISP. These days, internet scratch cards are also available. ISP will provide you a user name, password. It will also provide a telephone number to connect to internet.
      There are many ISPs these days in every big city of the country. A good ISP has the following features:
      · Low rate
      · Fast browsing
      · Fast downloading and uploading
      · Good customer support

      WEB PAGE

      A document created by HTML and found on web is a web page. A web page contains information in the form of text, pictures, audio and video clips. These web pages are stored on special computers called WEB SERVERS.

      WEB SITE

      A collection of related and interlinked web pages is called a web site. A web site may have many pages. Each web page will provide different information. For example, a web site for a College can have a Home page, Faculty page, Courses page, Games page and contact page. Home page is the main page of any web site. We can see all other pages by links provided in home page. Each web site has a unique address. For example web address of Baha-ud-din Zakaria University is www.bzu.edu.pk.

      WEB SERVER

      Web documents are stored on special and powerful computers called WEB SERVERS. Web servers are permanently connected to internet. When we type address of a web site in a browser (internet explorer), then web server fulfills this request. They provide requested information in the form of web page.

      WEB BROWSER

      A browser is software that is used to view web pages on internet. Many web browsers are available. But Mozilla Firefox, Google Chrome and Internet explorer are the most popular. We type address of any web site in address bar of browser and press ENTER key. Then first page called HOME PAGE of web site is displayed in browser window.
      Read More...

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