Connecting to the Internet:

* Internet communication protocols:

Computers connected to the internet communicate by using Internet Protocol (IP). IP slices information into packets and routes them to their destination. IP uses dynamic routing, so that even if one part of the network is knocked out, packets can be rerouted. Along with IP, most computers on the internet communicate with TCP.

* Internet host :

Each computer on the internet is called a host computer or host. Computers on the internet are connected by cables, phone lines and satellite connections. They include large mainframe, smaller mini computers and PCs.

* IP Address:

Each host computer on the internet has a unique number called its IP address.IP addresses identify the host computers, so that packets reach the correct computer. If we use dial-up account, ISP assigns your computer an IP address each time you connect. Computers on LAN usually have IP addresses that are reserved for use on LAN. The most common IP assignment server is called DHCP (Dynamic Host Configuration Protocol).

* Internet Service Providers (ISPs):

It is an organization that provides Internet accounts. The other features provided by the Internet account are Email mailboxes, Web server
space and Domain hosting.

* Types of Internet Connection:

So To connect to the internet we have different types of connections. They are:

Dial-Up connections:

This works over an ordinary phone line. It uses the point-to-point protocol. A modem is needed.DSL connections- Digital Subscriber Line is a digital, high-speed line that uses the normal phone wires with special modems on either end. The line is asymmetric, because it has more capacity for data received by the computer than for data sent from the computer. With DSL line we can connect the computer to the internet and talk on the phone at the same time on the same phone line.

DSL modems connect to the computer through an Ethernet or other network card in the
computer.

ISDN Connections:

Integrated Services Digital Network is an upgraded phone line that can be used for faster internet access and for regular voice calls. Using one line, we can talk on the phone and surf the web.o For residential use ISDN provides BRI. On one line, BRI provides two 64-Kbps channels, or B channels, and one 16-Kbps channel, or D channel. D channel is used for signaling. The two B channels are combined for to use the internet. An ISDN adapter is needed to connect the computer to an ISDN line.

Leased Lines:

If large amount of data is to be transferred we can go for leased line.o Leased lines come in various speeds including T1 and T3.

Cable TV internet connections:

Cable modem service brings dozens of TV channels as well as web sites. The cable network was designed to move information in one direction, from broadcaster to the user. Downstream speeds are much faster than the upstream speed.

Satellite Internet Connections:

Digital satellite Systems or direct broadcast satellite lets to get internet information by
satellite.· With early satellite systems, we can receive data from the internet at a high speed through the satellite, but to send data we need a dial-up connection and an ISP. Later the companies StarBand and DirecPC offered two-way system connection that doesn’t use a phone line at all, with uploads and downloads by satellite.

Wireless Internet Connections:

In a few urban areas wireless internet access can be used. To set it up, a radio modem is attached to the laptop. Another way to connect to the internet via wireless is by using a digital cell phone.Some ISPs offer wireless connections to Personal Data Assistants (PDA) such as Blackberry, Compaq ipaq, or Palm. These small devices have tiny screens which can be used to read e-mail and browse the web.

* Domain Name System·:

The name of each host computer consists of a series of words separated by dots. The last part of the domain name is called the top-level domain (TLD). The last two parts of a host computer name constitute the domain.· The second to last part of the name (second-level-domain) is chosen by the organization that owns the computer. Eg:yahoo.com· Because most organizations own more than on computer on the internet, most host computer names have at least one more part, preceding the domain name called third-level-domain. Eg: www.yahoo.com, mail.yahoo.com.

A domain name system (DNS) server translates between the numeric IP addresses that
identify each host computer on the internet and the corresponding domain names.

E-Mail Concepts:

E-mail messages are passed through the internet by using a protocol called simple mail
transfer protocol. The incoming messages are received in an e-mail mailbox that resides on a mail server.Mail servers receive and store e-mail messages in mailboxes by using a protocol called Post office Protocol or IMAP.

- To read e-mail, a mail client is needed.

- We can write e-mail messages by using e-mail application,

- The messages are transferred to an SMTP server

- a mail server that accepts e-mail.

* Ways Of accessing E-mail:

We may use a mail client. Eg: Eudora, Outlook, Outlook express, Netscape Messenger etc.· We may use a web-based e-mail service. We may use an online service, such as America online, which has its own mail program. We may get e-mail through a LAN, a common system at large organizations. The e-mail arrives in the company’s POP or IMAP server.

* E-mail Addressing:

Internet e-mail addresses consists of two parts joined by @ sign.

· User name – It contains characters other than letters-they can contain numbers,
underscores, periods, and some other special characters. They can’t contain commas or
parantheses.

· Host or domain name – It provides the internet location of the mailbox, usually the name of
a company or internet service.

* Formatted E-mail:

HTML – This is formatted with HTML tags, just like web pages. It includes text formatting, numbering, bullets, alignment, horizontal lines, backgrounds, hyperlinks. It is actually sent using the MIME protocol.

Rich Text Format – This format can be read by most word processing applications. Documents in this format are also called RTF files.

MIME (Multipurpose Internet Mail Extensions) – It is used for attachments. Formatting includes text formatting, pictures, video and sound.Web-Based E-mail· Using web based email we can access the web as well as read our mail.· Most web-based e-mail is free.

· We can read two kinds of messages on the web : Messages sent to a web-only accounto Messages stored in the POP mail box

Sending and Receiving Files by E-mail:

Attachments· An attachment is a file that has been encoded as text so that it can be included in an e-mail message.

The three common ways to encode e-mail attachments are :

MIME - Multi purpose Internet Mail Extension is the standard method.

Uencoding – This method is supported by some older e-mail applications.

BinHex- Used by some Mac e-mail programs.

* Sending Attachments: To send a file by e-mail, create a message to which the file is to be attached. Address the mail as usual and type the subject. If needed type the text in the body of the message.

· Now attach the file by choosing a menu command or by clicking a toolbar button.· Large files can be compressed, so that the sending and downloading time can be minimized.

* Receiving Attachments:

Most e-mail applications store the attachments in the mail message. First, open the message and then open or save the attachment. When the message with an attachment is deleted, the attachment is also deleted. To use the attachment later, it has to be saved.

* Attaching files to a Microsoft Outlook e-mail:

To attach files to a Microsoft Outlook, follow the below steps.

1. Open Microsoft Outlook.

2. Reply to an existing e-mail, or compose a new e-mail by clicking on the New icon in the top left portion of the window.

3. In the e-mail, click on the 'Insert file' icon that looks like a small paperclip, or click on Insert at the top of the window and choose file.

4. Browse to the location that contains your file and double-click it insert it.If successfully attached you should see an icon of the attachment in your e-mail.

Below is an alternative method of attaching a file into an e-mail.

1. Open My computer or Windows explorer and browse to the location of where your pictures are located.

2. Highlight and copy the picture you wish to send in an e-mail.

3. Open a new e-mail or the e-mail you're replying to that you wish to attach the file into, right-click in the message portion of the e-mail and click paste.Fighting Spam, Sorting Mail, and Avoiding Email Viruses

* Reducing Spam:

The term "spam" is Internet slang that refers to unsolicited commercial email (UCE) or unsolicited bulk email (UBE).Some people refer to this kind of communication as junk email to equate it with the paper junk mail that comes through the US Mail. Unsolicited email most often contains advertisements for services or products, but very few reputable marketers use UCE to advertise.

The most commonly seen spam includes the following: Foreign bank scams or advance fee fraud schemeso Phishing scams, a very popular and dangerous form of email fraudo Pyramid schemes, including multilevel marketing (MLM) Other "Get Rich Quick" or "Make Money Fast" (MMF) schemeso Quack health products and remedieso Ads for pornographic web siteso Offers of software for collecting email addresses and sending UCE Offers of bulk emailing services for sending UCE Chain letters (for more information, see About chain mail) Illegally pirated software

* Avoid receiving spam email: Spam has increasingly become a problem on the Internet. While every Internet user receives some spam email, certain behaviors on the Internet will cause you to receive even more than average.

· In fact, the Federal Trade Commission and the Center for Democracy and Technology have performed studies to determine how spammers can obtain your email address.

· They found that email addresses posted to web sites or in newsgroups attract the most spam.· Chat rooms are also fertile places for spammers to obtain email addresses.

· Some tips on Internet behavior that will help reduce the amount of spam you receive: On October 17, 2006, UITS implemented enhanced email filtering services at Indiana University. The spam quarantine service now analyzes all mail delivered to IU Cyrus/Webmail and Exchange accounts. Any spam messages you receive are quarantined for five days in a Spam (Cyrus/Webmail) or Junk E-mail (Exchange) folder in your account. After five days, the spam service deletes these messages automatically. Every time you communicate on the Internet or browse a web site, there are opportunities for spammers to intercept your communications to obtain your email address. In particular, if you post to a Usenet newsgroup, list your email address on a web site, or fill out insecure forms on the web, your address can be collected by spammers. They collect lists of email addresses and even share or sell these lists to other spammers. Even otherwise reputable companies may sell or exchange your email address with other companies, and this information may inadvertently find its way to a spammer. At worst, spammers will use automated programs to bombard these lists of email addresses with spam.

· Consider the following to reduce the amount of spam you receive:

Subscribe only to essential discussion lists, and ensure that they are moderated.If you are thinking of filling out a form on a web site, check the site's privacy policy first to be sure it uses secure technology and the company does not share your email address with others. If the site doesn't have a privacy policy that describes this to your satisfaction, consider not using that service.If you post to Usenet newsgroups or bulletin boards, or if you spend time in chat rooms or use an online service that displays your address, you may wish to consider opening an email account on a free service and using that address when performing these potentially spam-inducing activities. Then your primary account would not be as affected by spam.If the email address is listed on a web page, you should also consider opening a free account. If the web site listing your contact information is for Indiana University business, you could also get a departmental account and list that address rather than your personal address.If you reply to spam, the spammer or the automated program on the other end will then know that your address is connected to a live person, and the spammer will then bombard you with even more spam, and circulate your address to other spammers. Thus, it is imperative that you pause and think before replying to any spam.

* How to avoid viruses:

Do NOT open or view any attachment or file in email that you are not expecting. Even if you know the person sending you a file, it does not mean that the file is safe.· Newer email viruses can make it look as if your friends/colleagues are sending you the file. In short, whenever you receive a file by email, CHECK with the sender directly that the file is legitimate and if it is not, contact your IT support area. Following this rule will keep you safe from the vast majority of viruses going around the internet.

* General guidelines for avoiding computer viruses:Do not run, download or forward any unsolicited executables, documents, spreadsheets, etc. Anything that runs on your PC should be virus checked and approved first.Any email you weren't expecting should be treated with suspicion, even if it comes from someone you know. It is worth calling whoever sent it to you to check that they intended to send you the email.NEVER open any files with a double file extension, (e.g. iamavirus.txt.vbs). Under normal circumstances you should never need to receive or use these.Avoid downloading executables or documents from the internet. These are often used to spread computer viruses.Although JPG, GIF and MP3 files are not normally infected with viruses, some viruses can be disguised as these file types, also some recent software problems with image viewers and/or mp3 players have allowed them to contain viruses. Some caution is recommended when opening these file types. Jokes, pictures, graphics, screensavers and movie files should be treated with the same amount of suspicion as other file types.If in doubt, contact the ITS Service Desk for advice, do not open the file or email.If you think you have been infected with a virus inform the ITS Service Desk immediately. Do not panic or interrupt other users.Any virus warnings or hoaxes should be sent to the ITS Service Desk who can help confirm whether or not it is genuine. Do not forward these warnings to anyone else; unless you are signed up to an official virus alert service it is unlikely to be a genuine warning.Ensure that you follow the same procedures at home and elsewhere. Viruses can easily be spread from one location to another.Bank Scams: Ignore emails from banks, unless you have explicitly asked the bank to communicate with you via e-mail.Even if you have explicitly asked a bank to communicate with you via e-mail, be cautious if you choose to enter your account details such as your account number or pin into a website supplied via e-mail, as it may be forged.Online chatting, Messaging, and Conferencing Concepts· Online Chatting or online conferencing enables Internet users to exchange text or to have discussions with groups of people in real time.· The groups of people involved may be anywhere in the world.· This group communication can take the form of text, voice, or video, and messages and responses can be exchanged.

* Forms of Chat, Messaging and Conferencing· Real –time chatEach participant sees each message with seconds of when it is sent, and the reply is given quickly. However, all the participants need to be online at the same time.· Asynchronous chatMessages are stored so that participants can read them when they have a chance, which allow participants to consider their responses, gather information, and formulate a response carefully. It also allows people from different time zones or with different schedules to participate.

* Types of online chat and conferencing· E-mail Mailing Lists - E-mail messages are sent to one or more people who are selected by the sender. An e-mail mailing list allows messages to be distributed to a list of preselected people, called subscribers.· Usenet Newsgroups - Usenet is a system that allows messages to be distributed throughout the Internet. Due to the volume of messages, the messages are divided into newsgroups, or topics.· Internet Relay Chat (IRC) - It allows thousands of internet users to participate in real-time text-based chat.· Web-Based Chat - Many people are daunted by the programs and commands required by IRC. Hence, many web sites now provide a web-based way to participate in real-time text-based chat.· AOL and Compuserve Chat Rooms - AOL services allow real-time chat on a wide variety of subjects.· Instant Messaging - Instant messaging (IM) is a form of online communication that allows real-time interaction through computers or mobile devices.· Online conferencing - An online conference uses the Internet as a conference venue. This means that participants can access the conference from anywhere in the world and can do this at any time, using standard browser software.

Software Development Steps

Software Development Life Cycle:

The product developed which achieves customer satisfaction is not done in a single step. It involves series of steps in a software development process. This is needed to develop quality products with error free products to achieve customer satisfaction. There are many models available in the software development process.But majority of software development process follow the model named as software development life cycle. This software develop life cycle has number of steps in it. The below article describes about the software development life cycle and the steps involved into it.Software development life cycle model is also called as waterfall model which is followed by majority of systems.

This software development life cycle process has the following seven stages in it namely

1. System Requirements Analysis

2. Feasibility study

3. Systems Analysis and Design

4. Code Generation

5. Testing

6. Maintenance

7. Implementation

Let us discuss each of these to have an overview about teach of the following steps in software development life cycle.

1. System Requirements Analysis:

The first essential or vital thing required for any software development is system. Also the system requirement may vary based on the software product that is going to get developed. So a careful analysis has to be made about the system requirement needed for the development of the product. After the analysis and design of the system requirement phase the system required for the development would be complete and the concentration can be on the software development process.

2. Feasibility study:

After making an analysis in the system requirement the next step is to make analysis of the software requirement. In other words feasibility study is also called as software requirement analysis. In this phase development team has to make communication with customers and make analysis of their requirement and analyze the system. By making analysis this way it would be possible to make a report of identified area of problem.

By making a detailed analysis on this area a detailed document or report is prepared in this phase which has details like project plan or schedule of the project, the cost estimated for developing and executing the system, target dates for each phase of delivery of system developed and so on.

This phase is the base of software development process since further steps taken in software development life cycle would be based on the analysis made on this phase and so careful analysis has to be made in this phase.

3. Systems Analysis and Design:

This is an important phase in system development .Here analysis is made on the design of the system that is going to be developed. In other words database design, the design of the architecture chosen, functional specification design, low level design documents, high level design documents and so on takes place.

Care must be taken to prepare these design documents because the next phases namely the development phase is based on these design documents. If a well structured and analyzed design document is prepared it would reduce the time taken in the coming steps namely development and testing phases of the software development life cycle.

4. Code Generation:

This is the phase where actual development of the system takes place. That is based on the design documents prepared in the earlier phase code is written in the programming technology chosen. After the code is developed generation of code also takes place in this phase. In other words the code is converted into executables in this phase after code generation.

5. Testing:

A software or system which is not tested would be of poor quality. This is because this is the phase where system developed would be tested and reports are prepared about bugs or errors in system.

To do this testing phase there are different levels and methods of testing like unit testing, system test and so on.

Based on the need the testing methods are chosen and reports are prepared about bugs. After this process the system again goes to development phase for correction of errors and again tested. This process continues until the system is found to be error free. To ease the testing process debuggers or testing tools are also available.

To develop reliable and good quality Program/Software we need to follow the following five steps :

1. Requirement Specification.

2. Analysis.

3. Design.

4. Implementation.

5. Verification and testing.

Internet Evolution:

Internet Evolution:

The Internet is a network of networks

* Computer users on the Internet can contact one another anywhere in the world-In Internet a huge resource of information is accessible to people across the world—Information in every field starting from education, science, health, medicine, history, and geography to business, news, etc. can be retrieved through Internet— You can also download programs and software packages from anywhere in the world — In 1969 Department of Defense (DOD) of USA started a network called ARPANET (Advanced Research Projects Administration Network )— Around 1970, NSFNET (National Science Foundation Network) was created. With the advancement of modern communication facilities,— By 1990 many computers were looking up to NSFNET giving birth to Internet— Internet is not a governmental organization.— The ultimate authority of the Internet is the Internet Society.— This is a voluntary membership organization whose purpose is to promote global information exchange.— Internet has more than one million computers attached to it.— Ten years of research brought Local Area Ethernet Networks (LANs) and workstations were developed to get connected to LAN.— Computers connected to ARPANET used a standard or rule to communicate with each other with NCP (National Control Protocol).— Protocol is a network term used to indicate the standard used by a network for communication.— Rapid change in information technology suppressed NCP and brought TCP/IP (Transmission Control Protocol/Internet Protocol) in to the world of networking— The Internet is a rare example of a large democracy with no state of head, no official censors, no bosses, no board of directors. Nobody controls the Internet and in principle, any computer can speak to any other computer, as long as it obeys the technical rules of the TCP/IP protocol.— This freedom of Internet helped it to move out of its original base in military and research institutions, into elementary and high schools, colleges, public libraries, commercial sectors.

Basic Internet Terminology:

Blog - A blog is information that is instantly published to a Web site. Blog scripting allows someone to automatically post information to a Web site. The information first goes to a blogger Web site. Then the information is automatically inserted into a template tailored for your Web site.

Bookmark – a way of storing your favorite sites on the Internet. Browsers like Netscape or Internet Explorer let you to categorize your bookmarks into folders.Browser – A software program that allows users to access the Internet. Examples:Non-graphical a user interface for computers which allows you to read plain text, not pictures, sound, or video, on the Internet. It is strictly text based, non-Windows, and does not place high memory demands on your computer. An example is lynx .(http://lynx.browser.org/)Graphical a user interface for computers which enables people to see color, graphics, and hear sound and see video, available on Internet sites. These features are usually designated by underlined text, a change of color, or other distinguishing feature; sometimes the link is not obvious, for example, a picture with no designated characteristic. Examples are Netscape and Internet Explorer.CGI (Common Gateway Interface script) – a specificiation for transferring information between a Web server and a CGI program, designed to receive and and return data. The script can use a variety of languages such as C, Perl, Java, or Visual Basic. Many html pages that contain forms use a cgi program to process the data submitted by users/clients.Chat – real-time, synchronous, text-based communication via computer.

Cookie – Information (in this case URLs, Web addresses) created by a Web server and stored on a user’s computer. This information lets Web sites the user visits to keep of a user’s browsing pattterns and preferences. People can set up their browsers to accept or not accept cookies.

Domain Name – A method of identifying computer addresses. Your e-mail address has a domain address. If you have an “edu” at the end of your e-mail address that means your account is affiliated with an educational institution. A “com” extension means you have a business account. A government account has a .gov suffix.

FTP – Using file transfer protocol software to receive from upload) or send to (download) files (text, pictures, spreadsheets, etc.) from one computer/server to another. Home page - Generally the first page retrieved when accessing a Web site. Usually a “home” page acts as the starting point for a user to access information on the site. The “home” page usually has some type of table of contents for the rest of the site information or other materials. When creating Web pages, the “home” page has the filename “index.html,” which is the default name. The “index” page automatically opens up as the “home” page.

HTML – A type of text code in Hypertext Markup Language which, when embedded in a document, allows that document to be read and distributed across the Internet.HTTP – The hypertext transfer protocol (http) that enables html documents to be read on the Internet.

Hypertext – text that is non-sequential, produced by writing in HTML (Hypertext Markup Language) language. This HTML coding allows the information (text, graphics, sound, video) to be accessed using HTTP (Hypertext Transfer Protocol).Hyperlink – Text, images, graphics that, when clicked with a mouse (or activated by keystrokes) will connect the user to a new Web site. The link is usually obvious, such as underlined text or a “button” of some type, but not always.Instant Messaging (IM) – a text-based computer conference over the Internet between two or more people who must be online at the same time. When you send an IM the receiver is instantly notified that she/he has a message.

IP Address – (Internet Protocol) The number or name of the computer from which you send and receive information on the Internet.Modem – A device that connects your computer to the Internet, when you are not connected via a LAN (local area network, such as at work or on a campus.) Most people connect to a modem when using a home computer. The modem translates computer signals to analog signals which are sent via phone lines. The telephone “speaks” to the computer/server which provides your Internet access.

URL – A universal resource locator (a computer address) that identifies the location and type of resource on the Web. A URL generally starts with “http.”Intranet: It is a relatively smaller private network that uses the Internet protocols and connectivity. It is an extension of the Internet and is privately used by organizations.

Web Server: A web server is a computer program that accepts HTTP requests from web clients and provides them with HTTP responses.

IP Address: It is a way of numerically identifying an entity on a computer network. The original addressing system known as IPv4, used 32 bit addresses. With the growth of the Internet, IPv6 came to be used wherein the addresses are composed of 128 bits.

You might want to know how to find your IP address.Internet Service Provider: A company, which provides users with an access to the Internet, is known as an Internet service provider or Internet access provider. ISP, as it is called, offers email accounts and other services like remote storage of files for its customers. Here is a word about choosing a cheap ISP.Internet Address— Every page on the Internet has a unique address.— This address is used get the web page for user from Internet.— The address on the Internet is known as URL (Uniform Resource Locator).— A typical Internet address or URL would look like; http://www.mans.edu.eg/facscim/arabic/— The URL contains the components that specify the protocol, server, and pathname of an itemURL parts— The protocol is followed by a colon (http:),— The server is preceded by two slashes (//www.mnmjec.edu.)— Each segment of the pathname is preceded by a single slash /facscim/ /english/Tables/Default.htm).— A protocol is set of rules that tells the computer know how to interpret the information at that address— The first component, the protocol, defines the manner for interpreting computer information.— Many Internet pages use HTTP (HyperText Transfer Protocol).— Other common Internet protocols that one might come across are FTP (File Transfer Protocol),— NEWS (Usenet news groups protocol), and— GOPHER (an alternative transfer protocol). Gopher protocol is mostly out of date now.— The second component, of the address is the server (www.mnmjec.edu), identifies the computer system that stores the information you seek and is always preceded by two slashes.— A server is a computer that has information stored on it and sends it to the client, when a request is made.— Each server on the Internet has a unique address name whose text refers to the organization maintaining the server.— Most of the Web pages will have .htm or .html as their secondary or extension name.

Getting connected to Internet ApplicationsTypes of Internet Connections

There are two main ways for users to connect to the Internet: through dial-up access or by using a LAN connection.Dial-up Access Dial-up access allows access to the Internet over a standard telephone line by using a computer and a modem to dial into an ISP or VAN connection. Dial-up access is a feature typically included with the software provided by an ISP. Using a regular telephone line is usually the slowest telecommunications medium for setting up an individual Internet account through a dial-up ISP.

Local Area Network (LAN) Connection LAN connections provide faster and more direct Internet access by connecting users to an ISP on a direct wire, at speeds 30 or more times faster than can be achieved through a dial-up modem. Because they are more expensive than dial-up access, LAN connections are more commonly found in the workplace. Despite the increased cost there are approximately forty million LAN users in the United States using cable and DSL connections to connect from their homes.

Cable Modem Television cable companies provide a special modem and software for broadband (high-speed) Internet access. This service offers the advantage of simultaneous Web access and telephone calls, but is not available everywhere. In addition, the service slows down as more subscribers sign up in a neighborhood or location. The cost is about $50 monthly, plus a possible installation fee.

Digital Subscriber Line (DSL) DSL Internet service is as fast as cable modem and provides simultaneous Web access and telephone use, but the service is usually available only to users within three miles of the telephone carrier’s central switching office. The line is dedicated to one household, and is not shared with neighbors. DSL service costs around $50 monthly, plus an installation fee.Wireless The fastest growing segment of Internet service involves wireless connections to the Internet. Thousands of Wireless “hot-spot” portals are springing up, allowing access in public places and even aboard airplanes.— (i) Gateway Access— Gateway Access is also known as Level-One connection.— It is the access to the Internet from a network, which is not on the Internet.— The gateway allows the two different types of networks to “talk” to each other. But the users of the Gateway Internet have limited access to the Internet.— They might not be able to use all the tools available on Internet. The local Internet Service Provider (ISP) normally defines this limitation.Dial-up Connection— ‘Dial-up’ connection is also known as Level Two connection.— This provides connection to Internet through a dial-up terminal connection.— The computer, which provides Internet access is known as ‘Host’ and the computer that receives the access, is ‘Client’ or ‘Terminal’.— The client computer uses modem to access a “host” and acts as if it is a terminal directly connected to that host.— This type of connection is also known as ‘Remote Modem Access’ connection.— And the host to which the client gets connected is actually connected to the Internet by a full time connection (See Leased Connection).— In dial-up connection to Internet, Host carries all the command that are typed on a client machine and forward them to Internet.— It also receives the data or information from the Internet on behalf of the ‘Client’ and passes it to them. The client computer acts as a ‘dumb’ terminal connected to remote host.— This type of connection can further be divided into two categories.Shell Connection— In this type of Internet Connection, the user will get only textual matter of a Web Page.— This connection does not support Graphics display. However the user will be able to surf the Internet, do FTP, receive mail.— Shell Accounts were the only type of Internet access available for many years before the Internet entered in to the world of graphics and became more users friendly.TCP/IP Connection— Today’s graphical World Wide Web browsers provide easier access with multimedia sound and pictures.— The major difference between Shell and TCP/IP account is that, Shell account can only display text and does not support graphics display, whereas TCP/IP can display both.— Hence it is more popular Internet connection. Shell accounts are slowly phasing out from the Internet scenarioTo access any of these dial-up accounts you need the followings;$ computer, WebTV, personal digital assistant (PDA), or Web phone$ dial-up modem, digital subscriber line (DSL) modem, or cable modem$ telephone line or cable connection$ telecommunications software$ Web browser$ an account with an Internet Service Provider (ISP)Leased Connection— Leased connection is also known as direct Internet access or Level Three connection. — It is the secure, dedicated and most expensive, level of Internet connection.— With leased connection, your computer is dedicatedly and directly connected to the Internet using high-speed transmission lines.— It is on-line twenty-four hours a day, seven days a week.— Leased Internet connections are limited to large corporations and universities who could afford the cost.Newer Internet ApplicationsNot only does the content of the Internet change daily, but they very way in which the Internet is used and understood as a communication medium is constantly evolving.Peer-to-Peer File SharingPeer-to-Peer (P2P) file sharing allows people to download material directly from other users’ hard drives, rather than from files located on Web servers. Napster is famous for pioneering P2P file sharing.Internet TelephonyInternet telephony is another increasingly popular way to use the Internet. By using this technology, also called Voice over IP (VoIP), two or more users with sufficiently good connections can use the Internet to make telephone calls around the world. Once their voices are digitized and broken down into packets, they can be transmitted anywhere, just like any other form of data. There are no long distance telephone charges, and users only pay their normal ISP connection fees.

Operating System

Operating System:
The most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.

Types of Operating Systems:

Single user systems: A virtual machine with one user at any one time. Generally no provision to share resources. Major emphasis on simple command language or GUI, easy to use file system and standard I/O functionality involving disk/screen/printer.
Operating systems for home & personal computers fall into this category, examples of which would be CPM, MSDOS (Old 8 and 16 bit Operating Systems), Windows 9x, Windows ME, Windows XP, Linux (32 bit Operating Systems)Single user systems in a shared environment: a virtual machine with one main user, sharing resources over a local peer to peer network (a typical small office environment).
Examples: Windows NT, Windows 2000, LinuxThe following large enterprise based systems would probably use stable and scalable operating system such as Unix. Microsoft is attempting to break into this market with Windows 2000 /XP onwards.

Process control: Control by computer of an industrial process. A common feature is the use of feedback. Main features of such an operating system are reliability with a minimum of operator intervention and ‘fail safe’ routines in the event of hardware malfunction.Typical environments would be oil refining or railway signalling.

File Interrogation Systems: Where the computer is used as a database or repository of alarge amount of information about some aspect of the outside world. The user should be able to access the information without any knowledge of the internal organisation (in terms of software structure of hardware storage).

Transaction Processing Systems: Typically indicated by frequent modification of the database (several times per second), as in Banking or Airline control system. Should be able to handle the problems inherent in simultaneous access.

General Purpose Systems: Characterised by a large number of users performing a wide variety of independent tasks. Often classified into batch (no user interaction) or multi-access (user interaction).Distributed Systems: Interconnected computers sharing files, sending messages and sharing tasks.
Advantages: equalises the load of a system and allows programs to be executed on other machines more suitable to the task.Modern Operating System design increasingly incorporates complex communication methods to deal with the communications between computers and co-operating machines.

Common features of Operating SystemsConcurrency: Several processors and I/O devices in operation at the same time Sharing of resources: Sharing the processor(s), Store/Memory, I/O devices, programs Long term storage: Typically on disks Non-determinacy: Must be able to respond to events occurring in an unpredictable order in a consistent, error - free way.

OPERATING SYSTEM TYPES:As computers have progressed and developed so have the types of operating systems. Below is a basic list of the different types of operating systems and a few examples of Operating Systems that fall into each of the ategories. Many computer Operating Systems will fall into more then one of the below categories:
*GUI - Short for Graphical User Interface a GUI Operating System contains graphics and icons and is commonly navigated using by using a computer mouse. Below are some examples of GUI Operating Systems.System 7.x,Windows 98,Windows CE.
*Multi-user - A multi-user Operating System allows for multiple users to use the same computer at the same time and/or different times. Below are some examples of multi-user Operating Systems.Linux,UNIX,Windows 2000.
*Multiprocessing - An Operating System capable of supporting and utilizing more than one computer processor. Below are some examples of multiprocessingOperating Systems. Linux,UNIX,Windows 2000.
*Multitasking - An Operating systems that is capable of allowing multiple software processes to be run at the same time. Below are some examples of multitasking Operating Systems. UNIX,Windows 2000.
*Multithreading - Operating systems that allow different parts of a software program to run concurrently. Operating systems that would fall into this category are. Linux,UNIX,Windows 2000.
*Operating SystemsDOS , Linux, Windows (windows *9x, windows 2000 server windows ME and windows XP)Unix , OS/2,Mac,Netware, NT ,VMXDOS: (Disk Operating System) was developed by Microsoft. IBM also has its own version. It is a single tasking O/S, command line oriented and not user friendly. It is now been discontinued after version 6.22.
Windows:Windows is today the most popular O/S for businesses and home PCs particularly. This is because it is very user friendly, easy to use and has encouraged numerous people to use the computer. It allows you to do more than one thing at a time and has a stylish and easy to use GUI (graphical user interface). It even makes it easy for PCs not running its network versions to easily share resources in a peer-to-peer manner.
Windows has several flavours including:
Windows 3.0 – 1st version of windows, highly dependent on DOS for its O/S functionality
Windows 3.11- same as 3.0 but built with workgroup networks in mind
Windows 95 – very first window full O/S
Windows 98 – in improved version of Windows 95 with more utilities.
Windows millennium edition – home and multimedia version of win98 with even more utilities
Windows 2000 professional – a stable and security conscious version designed for professional use.
Windows 2000 server – a network version of windows 2000 with support for more file systems.
Windows data centre – a massive version of windows 2000 serverWindows XP – the latest version of windows.
Windows NT - the 1st network version of windows with support for up to 256 users per NT server. NT is an acronym for new technology.
Linux: a Unix based O/S best described as the G.U.I. version of Unix. It is more users friendly than it parent O/S and employs HCI’s metaphors a greater deal. Like windows it allows you to perform more than one task at a time.
Unix: an advanced O/S more suitable for network use. Unix is popular among large organisations particularly those with I.T. background. It is the best multi-user, multitasking O/S with extensive stability. Most web servers still utilises Unix. It has support for a wide range of software. Unfortunately it works like DOS being command line based.
O/S 2: This is IBM’s O/S in the late 70’s. It is similar to DOS but was discontinued rather quickly.
Mac: The Mac O/S is only used in Macintosh computers. It is user friendly with support for high graphics handling. It is also suitable for multitasking. Mac is now up to V08 O/S.
Netware: this is NOVEL’s popular network operating system with early support for dedicated and non-dedicated servers. Netware is a very security conscious NOS (Network Operating System) and administrative functions. It is fairly user friendly and way between Windows NT and Unix.
VMX: is an older O/S only popularly with organisations that use mainframe computers.

USING THE MOUSE

USING THE MOUSE:
The mouse is an input device which is moved on a flat surface called the mouse pad.When we move the mouse, a pointer called mouse pointer moves on the screen and it is used to point to things on the screen. Normally, the mouse has 2 or 3 buttons on top.

Move:

Moving the mouse is nothing but dragging the mouse on the mouse pad so that the mouse pointer moves in the direction you want, without touching the buttons. This action allows you to point to things on the screen.

Click:
Clicking is used to select an object on the screen. To do this, first we need to make the pointer point to that object and then press the left button once and release the button immediately.

Double-Click:
Double-clicking is used to start the applications. It is the same as clicking but here, we need to press the left button twice in quick succession. It requires some practice for the new users.

Click and Drag:
This is used to move an object from one place to another. To do this, we need to hold the left button down and while holding it down, we need to move the mouse to the place we want.

Right Click:
If you point to an item and click on the right button, you will be provided with a context sensitive menu. This menu provides almost all the facilities offered by menu as well as toolbars. We will learn more about this as and when it is required.

WINDOWS XP

WINDOWS XP:

We have so far been learning about computers in general. Now, let us start learning about an important and popular operating system known as 'Windows XP'.
In this chapter, let us see what is Windows XP and also some basic operations.

What is Windows XP?

Windows XP is a user-friendly operating system produced by Microsoft with a graphical user interface(GUI) for use on desktop and notebook computers. XP stands for 'experience'.
Windows XP is known for its improved stability and efficiency over the 9x versions of Microsoft Windows. It is also the first version of Windows to use product activation to combat software piracy. Windows XP is available in many languages.

Windows XP Editions :

The most common editions of the operating system are Windows XP Home Edition, targeted at home users, and Windows XP Professional,which has some additional features and targeted at power users, business and enterprise clients.
Windows XP Media Center Edition has additional multimedia features enhancing the ability to record and watch TV shows, view DVD movies, and listen to music.
Windows XP Tablet PC Edition is designed to run ink-aware applications built using the Tablet PC platform.
There is also Windows XP Embedded, a componentized version of the Windows XP Professional, and editions for specific markets such as Windows XP Starter Edition

What is GUI?

GUI is Graphical User Interface. Before we try to understand GUI, we must first see what is an interface. An interface is a (logical) connection between two entities, in this case between the user and the computer. It enables the user to interact with the computer.
Before the introduction of GUI, most of the operating systems used Command Line Interface(CUI), which required the users to remember some cryptic commands and type them without any errors. With GUI, all the information is displayed on the screen with pictures and hence it is very easy for the users to point and select the information that they want with the help of the mouse.

New Features in XP:

Windows XP introduced many features which were not found in previous versions of Windows. Some of them are listed below.
Faster start-up and hibernation sequences
The ability to discard a newer device driver in favor of the previous one (known as driver rollback), should a driver upgrade not produce desirable results
More user-friendly interface, including the framework for developing themes for the desktop environment
Fast user switching, which allows a user to save the current state and allow another user to log on without losing that information
The ClearType font rendering mechanism, which is designed to improve text readability on LCD monitors
Remote Desktop functionality, which allows users to connect to a computer running Windows XP Pro from across a network and access their applications, files, printers, and devices
Support for most DSL modems and wireless network connections.

System Requirements for XP:

The minimum hardware requirements for Windows XP Home/Professional Edition are:
Pentium 233-megahertz (MHz) processor or faster (300 MHz is recommended)
At least 64 megabytes (MB) of RAM (128 MB is recommended)
At least 1.5 gigabytes (GB) of available space on the hard disk
CD-ROM or DVD-ROM drive
Keyboard and a Microsoft Mouse or some other compatible pointing device
Video adapter and monitor with Super VGA (800 x 600)or higher resolution
Sound card
Speakers or headphones .

SUPER COMPUTERS

SUPERCOMPUTERS :
A supercomputer is the fastest type of computer. Supercomputers are very expensive and are employed for specialized applications that require large amounts of mathematical calculations. The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently.

Some Common Uses of Supercomputers :

Supercomputers are used for highly calculation-intensive tasks such as problems involving quantum mechanical physics, weather forecasting, climate research, molecular modeling (computing the structures and properties of chemical compounds, biological macromolecules, polymers, and crystals), physical simulations (such as simulation of airplanes in wind tunnels, simulation of the detonation of nuclear weapons, and research into nuclear fusion), cryptanalysis, and many others. Some supercomputers have also been designed for very specific functions like cracking codes and playing chess; Deep Blue is a famous chess-playing supercomputer. Major universities, military agencies and scientific research laboratories depend on and make use of supercomputers very heavily.

Hardware and Software Design:

Supercomputers using custom CPUs traditionally gained their speed over conventional computers through the use of innovative designs that allow them to perform many tasks in parallel, as well as complex detail engineering. They tend to be specialized for certain types of computation, usually numerical calculations, and perform poorly at more general computing tasks. Their memory hierarchy is very carefully designed to ensure the processor is kept fed with data and instructions at all times - in fact, much of the performance difference between slower computers and supercomputers is due to the memory hierarchy. Their I/O systems tend to be designed to support high bandwidth, with latency less of an issue, because supercomputers are not used for transaction processing.
Supercomputer designs devote great effort to eliminating software serialization, and using hardware to address the remaining bottlenecks.

Supercomputer challenges:
A supercomputer generates large amounts of heat and therefore must be cooled with complex cooling systems to ensure that no part of the computer fails. Many of these cooling systems take advantage of liquid gases, which can get extremely cold.
Another issue is the speed at which information can be transferred or written to a storage device, as the speed of data transfer will limit the supercomputer's performance. Information cannot move faster than the speed of light between two parts of a supercomputer.
Supercomputers consume and produce massive amounts of data in a very short period of time. Much work on external storage bandwidth is needed to ensure that this information can be transferred quickly and stored/retrieved correctly.

Operating Systems and Programming:
Most supercomputers run on a Linux or Unix operating system, as these operating systems are extremely flexible, stable, and efficient. Supercomputers typically have multiple processors and a variety of other technological tricks to ensure that they run smoothly.
Until the early-to-mid-1980s, supercomputers usually sacrificed instruction set compatibility and code portability for performance (processing and memory access speed).For the most part, supercomputers had vastly different operating systems. The Cray-1 alone had at least six different proprietary OSs largely unknown to the general computing community. Similarly different and incompatible vectorizing and parallelizing compilers for Fortran existed.
The base language of supercomputer code is generally Fortran or C, using special libraries to share data between nodes. Software tools for distributed processing include standard APIs and open source-based software solutions which facilitate the creation of a supercomputer from a collection of ordinary workstations or servers.

Processing Speeds:
Supercomputer computational power is rated in FLOPS (Floating Point Operations Per Second). The first commercially available supercomputers reached speeds of 10 to 100 million FLOPS. The next generation of supercomputers is predicted to break the petaflop level. This would represent computing power more than 1,000 times faster than a teraflop machine. A relatively old supercomputer such as the Cray C90 (built in the mid to late 1990s) has a processing speed of only 8 gigaflops. It can solve a problem, which takes a personal computer a few hours, in .002 seconds! From this, we can understand the vast development happening in the processing speed of a supercomputer.
The is dedicated to providing information about the current 500 sites with the fastest supercomputers. Both the list and the content at this site is updated regularly, providing those interested with a wealth of information about the developments in supercomputing technology.

Supercomputer Architecture:
Supercomputer design varies from model to model. Generally, there are vector computers and parallel computers. Vector computers use a very fast data “pipeline” to move data from components and memory in the computer to a central processor. Parallel computers use multiple processors, each with their own memory banks, to 'split up' data intensive tasks.
A vector computer solves a series of problems one by one in a consecutive order whereas a parallel computer solves all the problems parallely as it is equipped with multiple processors. Hence, the parallel computer would be able to solve the problems much quicker than a vector computer.
Other major differences between vector and parallel processors include how data is handled and how each machine allocates memory. A vector machine is usually a single super-fast processor with all the computer's memory allocated to its operation. A parallel machine has multiple processors, each with its own memory.
Vector machines are easier to program, while parallel machines, with data from multiple processors, could have trouble with communication of data between them.
Recently, parallel vector computers have been developed to take advantage of both designs.
Manufacturers of Supercomputers:
There are many manufacturers of good supercomputers and Cray is one among them. Cray provides an informative with product descriptions, photos, company information, and an index of current developments.
IBM produces supercomputers with most cutting-edge technology. For information about IBM supercomputers Their "Blue Gene" supercomputer, is expected to run 15 times faster at 200 teraflops than their current supercomputers. IBM's "Blue Sky" which is called a self-aware supercomputer will be used to work on colossal computing problems such as weather prediction. Additionally, this supercomputer can self-repair, requiring no human intervention.
Intel has developed a line of supercomputers known as Intel TFLOPS. Supercomputers that use thousands of Pentium Pro processors in a parallel configuration to meet the supercomputing demands of their customers. To know more about Intel supercomputers.
R & D on Supercomputers:
IBM is developing the Cyclops64 architecture, intended to create a "supercomputer on a chip".
IBM's 20 PFLOPS supercomputer named "Sequoia" is scheduled to go online in 2011.
Supercomputers are projected to reach 1 exaflops (one quintillion FLOPS) in 2019.
A zettaflops (one sextillion FLOPS) computer required to accomplish full weather modeling might be built around 2030.

Types of Computers based on Configuration

Types of Computers based on Configuration:
There are four different types of computers when we classify them based on their performance and capacity. The four types are

Super Computers
Mainframe Computers
Mini Computers
Micro Computers

Super Computers:
When we talk about types of computers, the first type that comes to our mind would be Super computers. They are the best in terms of processing capacity and also the most expensive ones. These computers can process billions of instructions per second. Normally, they will be used for applications which require intensive numerical computations such as stock analysis, weather forecasting etc. Other uses of supercomputers are scientific simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological data (e.g. in petrochemical prospecting). Perhaps the best known super computer manufacturer is Cray Research. Some of the "traditional" companies which produce super computers are Cray, IBM and Hewlett-Packard.

Mainframe Computers:
Mainframe computers can also process data at very high speeds vi.e., hundreds of million instructions per second and they are also quite expensive. Normally, they are used in banking, airlines and railways etc for their applications.

Mini Computers:
Mini computers are lower to mainframe computers in terms of speed and storage capacity. They are also less expensive than mainframe computers. Some of the features of mainframes will not be available in mini computers. Hence, their performance also will be less than that of mainframes.

Micro Computers:
The invention of microprocessor (single chip CPU) gave birth to the much cheaper micro computers. They are further classified into

Desktop Computers
Laptop Computers
Handheld Computers(PDAs)

Desktop Computers:
Today the Desktop computers are the most popular computer systems. These desktop computers are also known as personal computers or simply PCs. They are usually easier to use and more affordable. They are normally intended for individual users for their word processing and other small application requirements.

Laptop Computers:
Laptop computers are portable computers. They are lightweight computers with a thin screen. They are also called as notebook computers because of their small size. They can operate on batteries and hence are very popular with travellers. The screen folds down onto the keyboard when not in use.

Handheld Computers:
Handheld computers or Personal Digital Assistants (PDAs) are pen-based and also battery-powered. They are small and can be carried anywhere. They use a pen like stylus and accept handwritten input directly on the screen. They are not as powerful as desktops or laptops but they are used for scheduling appointments, storing addresses and playing games. They have touch screens which we use with a finger or a stylus.

Types of computer

TYPES OF COMPUTERS
Computers can be classified based on their principles of operation or on their configuration. By configuration, we mean the size, speed of doing computation and storage capacity of a computer.

Types of Computers based on Principles of Operation:
There are three different types of computers according to the principles of operation. Those three types of computers are

Analog Computers
Digital Computers
Hybrid Computers

Analog Computers:
Analog Computer is a computing device that works on continuous range of values. The results given by the analog computers will only be approximate since they deal with quantities that vary continuously. It generally deals with physical variables such as voltage, pressure, temperature, speed, etc
Digital Computers:
On the other hand a digital computer operates on digital data such as numbers. It uses binary number system in which there are only two digits 0 and 1. Each one is called a bit.
The digital computer is designed using digital circuits in which there are two levels for an input or output signal.
These two levels are known as logic 0 and logic 1.
Digital Computers can give more accurate and faster results.
Digital computer is well suited for solving complex problems in engineering and technology. Hence digital computers have an increasing use in the field of design, research and data processing.

Based on the purpose, Digital computers can be further classified as,
General Purpose Computers
Special Purpose Computers

Special purpose computer is one that is built for a specific application. General purpose computers are used for any type of applications. They can store different programs and do the jobs as per the instructions specified on those programs. Most of the computers that we see today are general purpose computers.

Hybrid Computers
A hybrid computer combines the desirable features of analog and digital computers. It is mostly used for automatic operations of complicated physical processes and machines. Now-a-days analog-to-digital and digital-to-analog converters are used for transforming the data into suitable form for either type of computation.For example, in hospital’s ICU, analog devices might measure the patients temperature, blood pressure and other vital signs. These measurements which are in analog might then be converted into numbers and supplied to digital components in the system. These components are used to monitor the patient’s vital sign and send signals if any abnormal readings are detected. Hybrid computers are mainly used for specialized tasks.

Basic Computer

What is computer?

Computer is a faster working electronic, programmable, data processing device. Computer cannot do anything independently. It acts on the instructions from the user and processes it, gives the result in the desired form.

Application of computer
Some of the applications of the computer are given below.

Maintenance of accounts and producing reports.
Purchasing and stock control in super markets and factories.
Library book issue management and information retrieval.
Computer aided diagnosis of diseases.
Bank accounts and instant customer service.
Organization of examinations and tabulation of results.
Computer aided design of building, plants, and machinery.
Weather forecasting.
Computer controlled machines.
Computer aided learning.
Word processing and desk top publishing.
Crime detection – finger print processing and image processing.

Computer system characteristics:

Perform complex and repetitive calculations rapidly and accurately.
Storage large amounts of data and information for subsequent manipulations.
Hold a program of a model which can be explored in many different ways.
Make decisions.
Provide information to the user.
Automatically correct or modify – by providing signals – certain parameters of a system under control.
Draw and print graphs, and
Converse with users through terminals.