Wednesday 7 September 2011

CHAPTER 9 : INTRODUCTION TO HTML

What is HTML?
HTML is a language for describing web pages.
  • HTML stands for Hyper Text Markup Language
  • HTML is not a programming language, it is a markup language
  • A markup language is a set of markup tags
  • HTML uses markup tags to describe web pages

HTML Tags
HTML markup tags are usually called HTML tags.
  • HTML tags are keywords surrounded by angle brackets like <html>
  • HTML tags normally come in pairs like <b> and </b>
  • The first tag in a pair is the start tag, the second tag is the end tag
  • Start and end tags are also called opening tags and closing tags  


HTML Documents = Web Pages


        The purpose of a web browser (like Internet Explorer or Firefox) is to read HTML documents and display them as web pages. The browser does not display the HTML tags, but uses the tags to interpret the content of the page:



<html>
<body>

<h1>My First Heading</h1>

<p>My first paragraph.</p>

</body>
</html>








 Explained


  • The text between <html> and </html> describes the web page
  • The text between <body> and </body> is the visible page content
  • The text between <h1> and </h1> is displayed as a heading
  • The text between <p> and </p> is displayed as a paragraph





  • HTML documents describe web pages
  • HTML documents contain HTML tags and plain text
  • HTML documents are also called web pages

Posted by computer's group at 01:11 0 comments

CHAPTER 8 : INTRODUCTION TO THE INTERNET

History of Internet

 

 

•    IN 1969- US funded a project that develop a national computer called Advanced Research Project Agency Network (ARPANET).
•    Large network that connects together smaller network all over the globe.
•    Internet is a publicly available, global network of computers.
•    Interconnects billions of users. For example:
  • Businesses
  • Citizens
  • Governments
  • Academic Institutions
  • Research Centers
  • Libraries
        Applications of the Internet

    The internet is used for a many of applications. For example:
o   WWW
o   Email
o   Instant messaging

 

 
 WORLD WIDE WEB (WWW)

 

 
n The world wide web is a sophisticated system for universal information capture and delivery
n The world wide web consortium (W3C) definition of the web: "The World Wide Web is the   universe of network-accessible information, an embodiment of human knowledge"
n Provides information access in ways not previously possible
Ø  Hyperlinked (Hypertext)
Ø  Graphical user interface
Ø  Pictorial and non-text information
Ø  Information that changes rapidly
Ø  Immediate access
Ø  Anyone can author a web site
Ø  Multi-user access to the same information (try that with a book)
Ø  Easily searchable information

 
n  The functionality of the WWW is based on 3 main standards:
Ø  URL (Universal Resource Locator)
Ø  HTML (Hypertext Markup Language)
Ø  HTTP (Hypertext transfer Protocol)

 

 

 

 
INTERNET ADDRESS

 

 
  • URL = Universal Resource Locator
  • URL is the address window just below the toolbar buttons will usually contain the unique addres of a web page or file on the Internet.
  • HTTP – Hypertext Transfer Protocol (http://) is the means of communicating by using links, the clickable text or image that transport a user to the desired web site.
  • HTTPS – Hypertext Transfer Protocol Secure (https://)
  • HTTPS connections are often used for payment transactions and for sensitive transactions in corporat Domain name is the address of the site’s host computer.
  • The last part of the domain name , “com” called top-level domain and represents the purpose of organization or entity.
  •  com is commercial,
  •  edu is education,
  • gov is government,
  • org is organization,
  • net is networking center.
  • e information systems.
 

 
E-mail

 

 

  • E-mail or electronic mail is the transmission of electronic messages over the Internet.
  • A typical e-mail message has three basic elements : header. Message and signature.
  • Addresses : Addresses of the person sending, receiving, and optionally, anyone else who is to receive copies.
  • Subject : A line description, used to present the topic of the message. Subject lines typically are displayed when a person checks his or her mailbox.
  • Attachments : many e-mail programs allow you to attach files such as documents and image files.
  • Signature : Provides additional information about the sender. This information may include the sender’s name, address and telephone number.
 
WEB BROWSERS

 

 
  • A browser is software used to explore the Internet.
  • Microsoft Internet Explorer (IE) is by far the most popular browser, probably because it is included with Windows
  • Others like Google Chrome, Netscape, Opera and Mozilla are available too.

 

 

 

 

 
SEARCH ENGINES

 

 
  • A search engine is software, usually located at its own web site, that lets a user specify search terms; the search engine then finds sites that fit those terms.
  • A browser usually offers links to one or more search engines, or a user can simply link to the site of a favorite search engine.
  • Examples : yahoo!, bing, google, msn, altavista etc.
 
 

 

 

 

 
INTERNET SERVICES

 

 
  •  E-mail
  •  Instant Messaging
  • Chat
  • Online shopping
  • Banking transaction
  • Web Information System (e-learning etc)
  • Online application
  • E-commerce
  • Social network (Facebook, Twitter, Blogs, Foursquare etc)
 

 

 
 
Posted by computer's group at 01:10 0 comments

CHAPTER 7 :DATA COMUNICATIONS

DATA COMMUNICATIONS

Types of communication :



Any communications channel has a direction associated with it:



        The message source is the transmitter, and the destination is the receiver. A channel whose direction of transmission is unchanging is referred to as a simplex channel. For example, a radio station is a simplex channel because it always transmits the signal to its listeners and never allows them to transmit back.



The basic components of data communications are:
  Sending device -> Modem -> ommunications link ->  Modem -> Receiving device

NETWORK
è          Series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain subnetworks.

  • LAN
LANs (local area networks) are networks that connect computers and resources together in a building or buildings close together. 



  • MAN
Metropolitan Area Networks (MANs) are networks that connect LANs together within a city.

  • WAN
Wide Area Networks (WANs) connect LANs together between cities. 

  

Network topology


  • Bus Network
  • each node is connected to a single cable. 
  • A signal from the source travels in both directions to all machines connected on the bus cable    until it finds the intended recipient. 
  • If the machine address does not match the intended address for the data, the machine ignores the data. Alternatively, if the data does match the machine address, the data is accepted.
  • it is rather inexpensive to implement when compared to other topologies. However, the low cost of implementing the technology is offset by the high cost of managing the network. Additionally, since only one cable is utilized, it can be the single point of failure If the network cable breaks, the entire network will be down.
  • Star Network
  •  Each network host is connected to a central hub with a point-to-point connection. 
  • All traffic that traverses the network passes through the central hub. The hub acts as a signal repeater. 
  • The star topology is considered the easiest topology to design and implement. 
  • An advantage of the star topology is the simplicity of adding additional nodes. 
  • The primary disadvantage of the star topology is that the hub represents a single point of failure.
  • Ring Network


  • A network topology that is set up in a circular fashion in which data travels around the ring in one direction and each device on the right acts as a repeater to keep the signal strong as it travels. 
  • Each device incorporates a receiver for the incoming signal and a transmitter to send the data on to the next device in the ring. 
  • The network is dependent on the ability of the signal to travel around the ring
                            Communications Devices
  • Communications devices
    • Communications Devices is any type of hardware capable of transmitting data, instructions, and information between devices.
                                                             
  • Dial-up modem
    • Dial-up modem is convert digital signals to analog and vice versa.
    • Notebook computers often use PC Card modem. 
  • Cable modem
    • Sends and receives data over cable television network.
    • Much faster than dial-up modem or ISDN.
  • Wireless modem
    • Allows access to the Web wirelessly from a notebook computer, a PDA, a smart phone, or other mobile device.
    • Typically use the same waves used by cellular telephones.


  • Network Card
    • Adapter Card,PC Card, Express Card module, USB network adapter or flash card that enables a computer or devices to access network.
  • Wireless Access Point
    • Central communication device that allows computers and device to transfer data wirelessly among themselves or to wired network.
  • Router
    • Connect computers and transmits data to connect destination on network
    • Router forward data on the Internet using fastest available path

COMMUNICATION MEDIA
  • Wire pair/Twisted pair
    • The most communication media
    • Wire pairs are inexpensive

  • Coaxial cable
    • Known for sending a strong signal
    • coaxial cables has much higher bandwidth
  • Fiber Optic
    • Fiber optics use light and the cables are made of glass or plastic fibers, each thinner than a human hair
    • Fiber optics cables has a much higher bandwidth than coaxial cables, yet less expensive
    • It uses light rather than electricity

  • Microwave transmission
    • Use as line-of-sight transmssion of data signals via atmosphere.
    • Often antennas in high places, such as the tops of mountains and buildings-positioned at point as approximately 30 miles apart to continue the transmission.
    • Microwave transmission offers high speed, cost-effectiveness and ease implementation.
    • One problem is susceptibility to interference by whether conditions.
    • Satellite transmission
      • Satellite transmission is a form of microwave transsmission in which a satellite acts as the relay station.
      • Its basic component are earth stations, which send and receive signals.
      • Transponder is the satellite components that receive the transmission from an earth.
      • This entire process takes only a fraction of a second.
    • Wireless transmission
      • Wireless transmission is a group of technologies has recently emerged that transmit data over relatively short distances.
      • IrDA uses infrared to transmit data a few feet between devices, such a PDA and a desktop or a computer and a printer.
      • Similar to TV remote, IrDA requires a direct line-of-sight.
      • Bluetooth is another short distance technique(30 feet or less) that uses radio waves to connect mobile devices such as handhelds, notebooks and cell phones.
      • Wi-fi (wireless fidelity) is a standard uses for distance up to about 150 feet.
      • Wi-fi capability is built into some notebook model, allowing them to easily join wireless LANs.
      • 802.11a and 802.11g are the newest members of this family and allow transmission at speeds up to 54 Mbps.

    BITS AND BYTE
    • Bit
      •  Short for binary digit.
        • Two possible value : 0 and 1
        • Can never be  empty
      • Basic unit for storing data.
        • 0 means off, 1 means on.
    • Byte
      • A group of 8 bits
        • Each bit has 256 (28) possible values.
      •  For text, stores one character
        • Can be letter, digit or special character
    • Memory and storage devices measured in number of byte.
    Posted by computer's group at 00:05 0 comments

    Tuesday 6 September 2011

    CHAPTER 6 : MICROSOFT EXCEL


             Software developed and manufactured by Microsoft Corporation that allows users to organize, format, and calculate data with formulas using a spreadsheet system broken up by rows and columns. Microsoft Excel usually comes bundled with Microsoft Office and is compatible with other applications offered in the suite of products. The first software program similar to Excel was released in 1982 and was called Multiplan. Microsoft Excel has the basic features of all spreadsheets, using a grid of cells arranged in numbered rows and letter-named columns to organize data manipulations like arithmetic operations.




    Posted by computer's group at 23:19 0 comments

    CHAPTER 5 : MICROSOFT POWER POINT

     
    MICROSOFT POWER POINT



              Microsoft PowerPoint, usually just called PowerPoint, is a commercial presentation program developed by Microsoft. It is part of the Microsoft Office suite, and runs on Microsoft Windows and Apple's Mac OS X operating system. The current versions are Microsoft PowerPoint 2010 for Windows and 2011 for Mac.
            PowerPoint presentations consist of a number of individual pages or "slides". The "slide" analogy is a reference to the slide projector. Slides may contain text, graphics, sound, movies, and other objects, which may be arranged freely. PowerPoint, however, facilitates the use of a consistent style in a presentation using a template or "Slide Master".
           The presentation can be printed, displayed live on a computer, or navigated through at the command of the presenter. For larger audiences the computer display is often projected using a video projector. Slides can also form the basis of webcasts.

           PowerPoint provides three types of movements:

    1. Entrance, emphasis, and exit of elements on a slide itself are controlled by what PowerPoint calls Custom Animations
    2. Transitions, on the other hand are movements between slides. These can be animated in a variety of ways
    3. Custom animation can be used to create small story boards by animating pictures to enter, exit or move.



    Part of Microsoft Power Points are:


    Title bar - displays the document name
    Menu bar - click on a menu option to see a list of commands
    Standard toolbar - frequently used menu options
    Formatting toolbar - displays formatting commands
    Placeholder - click or double-click to add an element to a slide
    Outline view button - displays document in outline form
    Slide view button - displays slides one at a time
    Slide Sorter view button - displays all slides in a single screen
    Slide show button - displays slide show
    Drawing toolbar - displays drawing tools
    Status bar - shows the current page number and position of the insertion point in the document
    Office Assistant - quick help when you need it

    Posted by computer's group at 23:18 0 comments