Friday, November 21, 2008

What is an internet


What is the Internet:
The word internet is used to describe a network of networks which incorporate a very large and complicated set of equipment. To understand the internet, there are three areas of discussion which are very helpful. These include the various services provided across the internet, the functions that enable the internet to work, and the various organizations that are part of the internet.
Internet Services:
The main services used on the internet include:

  • Web browsing - Supported by the HTTP protocol, this functions allows users to view web pages using a web browser.
  • E-mail - Allows people to send and receive electronic messages.


Other lesser used services include telnet (allows remote login to computers), FTP (Allows quick file transmission to remote computers), and gopher (An early form of text based form of reading internet documents which is rarely used today).


Internet Functions:
The internet provides for the following two functions which support communications. Without the communications support mentioned below, the internet could not function. These two functions are provided by internet service providers listed below under the "Internet Organizations" header.

  • Physical lines that data is sent across.
  • Routing of data - There are special machines on the internet called routers, that determine where data needs to go to get from the sender of the data to the receiver of the data.



Internet Organizations:

  • ISPs (Internet Service Providers) - They provide the connection to the internet for users and also provide routers that direct internet traffic.
  • Corporations or Web hosting providers with mail servers and web servers - They provide the information posted on the internet and virtual data connections to other mail servers.


There are also other organizations that regulate the internet, providing communication standards and designing new communication standards for improvements. These communication standards are also known as protocols.


Summary:
So the internet is a collection of organizations that provide equipment that support the internet functions and services. The internet connects many corporate and organizational private networks together thus enabling all these organizations to easily communicate.


Accessing the Internet:
People use an internet browser to access web pages that are available across the internet. Internet browsers include Microsoft Internet Explorer, Netscape Navigator, Mozilla, and others.


Web pages are created in a marked up form of text file called HTML (Hyper-Text Markup Language). The markup within the text indicates document structure showing where paragraphs begin and end, what items are in a list, headers, tables and other document structure.


When people are browsing of surfing the internet, they usually go from place to place by clicking on links. These links are locations for specific pages and indicate the three things:

  • Protocol being used such as http or ftp.
  • The domain that the web page is found on. This will point to a specific organization's or company's web server.
  • The location of the page on the server including the directory path and file name.


An example link is "http://www.comptechdoc.org/basics/bastutorial/osintro.html". In this case http is the protocol being used, the comptechdoc.org domain indicates where the organization's web server is, and the "/basics/bastutorial/osintro.html" part of the string indicates the folders the file is in and the name of the file.


These links are sometimes called hyperlinks or URLs (Uniform Resource Locators)

Thursday, September 25, 2008

Chapter 1.Introduction

Introduction



Computers are showing up everywhere you look, and even in places you can't see. Computers check out your groceries, pump your gas, dispense money at the ATM, turn the heat on and off, control the way your car runs. They're everywhere! They're everywhere! In fact, the computer is rapidly becoming, if it hasn't already gotten there, as tightly woven into the fabric of our lives as the automobile. The analogy runs quite deep. Computers play a key role in how individuals work and how they live. Even the smallest organizations have computers to help them operate more efficiently, and many individuals use computers at home for educational, entertainment, and business purposes. In this session, you will learn the basics about computers, the history of computers, the different categories of computers, hardware and software, and maintaining your computer. You will also learn about computer applications in education and explore various technology issues that are related to computers such as security, privacy and ethics.

Chapter 2.History of Computer

History of Computer





The development of the modern day computer was the result of advances in technologies and man's need to quantify. The abacus was one of the first counting machines. Papyrus helped early man to record language and numbers. Some of the earlier counting machines lacked the technology to make the design work. For instance, some had parts made of wood prior to metal manipulation and manufacturing. Imagine the wear on wooden gears. This history of computers site includes the names of early pioneers of math and computing and links to relating sites about the History of Computers for further study. This site would be a good Web adjunct to accompany any book on the History of Computers or Introduction to Computers. The "H" Section includes a link to the History of the Web Beginning at CERN which includes Bibliography and Related Links. Hitmill.com strives to always include related links for a broader educational experience.Nearly 5,000 years ago the abacus emerged in Asia Minor. The abacus may be considered the first computer. This device allowed its users to make computations using a system of sliding beads arranged on a rack. Early shopkeepers used the abacus to keep up with transactions. The use of pencil and paper spread, the abacus lost its importance. Nearly twelve centuries past before the next important advance in computing devices emerged. In 1642, Blaise Pascal, the 18-year-old son of a French tax collector, invented what he called a numerical wheel calculator to help his father with his duties. The Pascaline, a brass rectangular box, used eight movable dials to add sums up to eight figures long. Pascal's device used a base of ten to achieve this. The disadvantage to the Pascaline, of course, was its limitation to addition. In 1694, Gottfried Wilhem von Leibniza a German mathematician and philosopher improved the Pascaline by creating a machine that could also multiply. Like its predecessor, Leibniz's mechanical multiplier worked by a system of gears and dials.It wasn't until 1820, however, that mechanical calculators gained widespread use. A Frenchman, Charles Xavier Thomas de Colmar, invented a machine that could perform the four basic mathematic functions. The arithometer, presented a more systematic approach to computing because it could add, subtract, multiply and divide. With its enhanced versatility, the arithometer was widely used up until World War I. The real beginnings of computers began with an English mathematics professor, Charles Babbage. Babbage's steam-powered Engine, outlined the basic elements of a modern general purpose computer and was a breakthrough concept. The Analytical Engine consisted of over 50,000 components. The basic design of included input devices in the form of perforated cards containing operating instructions and a "store" for memory of 1,000 numbers of up to 50 decimal digits long. In 1889, an American inventor, Herman Hollerith, created a machine that used cards to store data information which was fed into a machine and compiled the results mechanically. Each punch on a card represented one number, and combinations of two punches represented one letter. As many as 80 variables could be stored on a single card. Hollerith brought his punch card reader into the business world, founding Tabulating Machine Company in 1896, later to become International Business Machines (IBM) in 1924 after a series of mergers. Other companies also manufactured punch readers for business use. Both business and government used punch cards for data processing until the 1960's. When World War II began, the governments sought to develop computers to accomplishment their potential strategic importance. This increased funding for computer development projects and hastened technical progress. In 1941, a German engineer Konrad Zuse had developed a computer to design airplanes and missiles. The Allied forces, however, made greater strides in developing powerful computers. American efforts produced a broader achievement. In 1933, Howard H. Aiken, a Harvard engineer working with IBM, succeeded in producing an all-electronic calculator. The purpose of the computer was to create ballistic charts for the U.S. Navy. It was about half as long as a football field and contained about 500 miles of wiring. It used electromagnetic signals to move mechanical parts. The machine was slow taking 3-5 seconds per calculation and inflexible in that sequences of calculations could not change; but it could perform basic arithmetic as well as more complex equations. Another computer development spurred by the war was the Electronic Numerical Integrator and Computer (ENIAC). It consisted of 18,000 vacuum tubes, 70,000 resistors and 5 million soldered joints, the computer was such a massive piece of machinery that it consumed 160 kilowatts of electrical power. ENIAC was developed by John Presper Eckert and John W. Mauchl. ENIAC was a general-purpose computer. In 1945, Von Neumann designed the Electronic Discrete Variable Automatic Computer (EDVAC) with a memory to hold both a stored program as well as data. This "stored memory" technique as well as the "conditional control transfer," that allowed the computer to be stopped at any point and then resumed, allowed for greater versatility in computer programming. The key element to the von Neumann architecture was the central processing unit, which allowed all computer functions to be coordinated through a single source. In 1951, the UNIVAC I (Universal Automatic Computer), built by Remington Rand, became one of the first commercially available computers to take advantage of these advances. The first computers were characterized by the fact that operating instructions were made-to-order for the specific task for which the computer was to be used. Each computer had a different binary-coded program called a machine language that told it how to operate. This made the computer difficult to program and limited its versatility and speed. Other unique features of first computers were the use of vacuum tubes and magnetic drums for data storage.The invention of the transistor greatly changed the computer's development in 1948. The transistor replaced the large, cumbersome vacuum tubes. The transistor was at work in the computer by 1956. Throughout the early 1960's, there were a number of commercially successful computers used in business, universities, and government from companies such as Burroughs, Honeywell, IBM, and others. These computers also contained transistors in place of vacuum tubes. They also contained all the components we associate with the modern day computer: printers, disk storage, memory, tape storage, operating systems, and stored programs.By 1965, most large business routinely processed financial information using computers. It was the stored program and programming language that gave computers the flexibility to finally be cost effective and productive for business use. Though transistors were clearly an improvement over the vacuum tube, they still generated a great deal of heat, which damaged the computer's sensitive internal parts. Jack Kilby, an engineer with Texas Instruments, developed the integrated circuit in 1958. The IC combined three electronic components onto a small silicon disc, which was made from quartz. Scientists later managed to fit even more components on a single chip, called a semiconductor. By the 1980's, very large scale integration squeezed hundreds of thousands of components onto a chip. Ultra-large scale integration increased that number into the millions. The ability to fit so much onto an area about half the size of a dime helped diminish the size and price of computers. It also increased their power, efficiency and reliability. By the mid-1970's, computer manufacturers sought to bring computers to general consumers. These minicomputers came complete with user-friendly software packages that offered even non-technical users an arrangement of applications, most popularly word processing and spreadsheet programs.. In 1981, IBM introduced its personal computer (PC) for use in the home, office and schools. The 1980's saw an expansion in computer use in all three arenas as clones of the IBM PC made the personal computer even more affordable. The number of personal computers in use more than doubled from 2 million in 1981 to 5.5 million in 1982. Ten years later, 65 million PCs were being used. As computers became more widespread in the workplace, new ways to harness their potential developed. As smaller computers became more powerful, they could be linked together, or networked, to share memory space, software, information and communicate with each other. Computers continue to grow smaller and more powerful.

Chapter 3. Hardware and Sofware

Hardware and Software
The hardware are the parts of computer itself including the Central Processing Unit (CPU) and related microchips and micro-circuitry, keyboards, monitors, case and drives (floppy, hard, CD, DVD, optical, tape, etc...). Other extra parts called peripheral components or devices include mouse, printers, modems, scanners, digital cameras and cards (sound, colour, video) etc... Together they are often referred to as a personal computer or PC.
Central Processing Unit - Though the term relates to a specific chip or the processor a CPU's performance is determined by the the rest of the computer's circuitry and chips.

The software is the information that the computer uses to get the job done. Software needs to be accessed before it can be used. There are many terms used for process of accessing software including running, executing, starting up, opening, and others.
Computer programs allow users to complete tasks. A program can also be referred to as an application and the two words are used interchangeably.
Examples of software programs or applications would be the Operating System (DOS, Windows 9x/Millenium/XP, O/S2, UNIX, MacOS 9.x/10.x and various others), Wordprocessor (typing letters), Spreadsheet (financial info), Database (inventory control and address book), Graphics program, Internet Browser, Email and many others.

Chapter 4.Categories Of Computer

Categories of Computer






The five categories of computer are:

Super Computers
Mainframe Computers
Workstation computer
Minicomputer
Micro Computer

Supercomputer :


A computer which, among existing general-purpose computers at any given time, often in several senses: highest computation rate, largest memory, or highest cost.

Mainframe Computers:

A large digital computer serving 100-400 users and occupying a special air-conditioned room.

Workstation computers:This computer has more computing capacity in its CPU than a typical personal computer.Scientists and engineers are the main users of workstations, although people who process graphics find a workstation necessary, since the processors can handle the huge amounts of data associated with graphic files.

Minicomputer: A mid-sized computer, usually fitting within a single cabinet about the size of a refrigerator, that has less memory than a mainframe.

Micro Computer : A personal computer

Chapter 5. Input Devices

Input Devices


An input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system (such as a computer). Input and output devices make up the hardware interface between a computer and the user or external world.

Types of Input

Data is the raw facts given to the computer.

Programs are the sets of instructions that direct the computer.

Commands are special codes or key words that the user inputs to perform a task, like RUN "ACCOUNTS". These can be selected from a menu of commands like "Open" on the File menu. They may also be chosen by clicking on a command button.

User response is the user's answer to the computer's question, such as choosing OK, YES, or NO or by typing in text, for example the name of a file.


Some Common Computer Input Devices:

Keyboard :The first input device we will look at is the Keyboard. The image used on the next page to illustrate the various keys may not look like the keyboard you are using. Several variations are popular and special designs are used in some companies. The keyboards shown below put the function keys in different places. The Enter and Backspace keys are different shapes and sizes. One has arrow keys while the other doesn't. It's enough to confuse a person's fingers!!
The backslash key has at least 3 popular placements: at the end of the numbers row, above the Enter key, and beside the Enter key. We also have the Windows keyboards which have two extra keys. One pops up the Start Menu and the other displays the right-click context sensitive menu. Ergonomic keyboards even have a different shape, curved to fit the natural fall of the wrists.
Mouse - Most modern computers today are run using a mouse controlled pointer. Generally if the mouse has two buttons the left one is used to select objects and text and the right one is used to access menus. If the mouse has one button (Mac for instance) it controls all the activity and a mouse with a third button can be used by specific software programs.
One type of mouse has a round ball under the bottom of the mouse that rolls and turns two wheels which control the direction of the pointer on the screen. Another type of mouse uses an optical system to track the movement of the mouse.

Pointing Devices :
Pointing devices move some object on the screen and can do some action
Common pointing devices

Track ball -

basically an upside down mouse
Joystick
Game controller
Scanner :
A scanner allows you to scan documents, pictures, or graphics and view them on the computer. You can also use software to edit the items you scan.Used to put printed pictures and text into a computerConverts an image into dots that the computer can understandTo scan text, optical character recognition (OCR) software is needed
Digital Camera :
Used to take electronic pictures of an object
The pictures taken by a digital camera can be used directly by a computer
CD-ROM/DVD-ROM:
Can be used to put both sound and images into a computer
Use a laser to read a Compact Disk (CD) or a DVD disk

Chapter 6. Processing

Porcessing

Processing is the thinking that the computer does - the calculations, comparisons, and decisions. People also process data. What you see and hear and touch and feel is input. Then you connect this new input with what you already know, look for how it all fits together, and come up with a reaction, your output. "That stove is hot. I'll move my hand now!"
The kind of "thinking" that computers do is very different from what people do.
Machines have to think the hard way. They do one thing at a time, one step at a time. Complex procedures must be broken down into VERY simple steps. Then these steps can be repeated hundreds or thousands or millions of times. All possible choices can be tried and a list kept of what worked and what didn't.
People, on the other hand, are better at recognizing patterns than they are at single facts and step-by-step procedures. For example, faces are very complex structures. But you can identify hundreds and even thousands of different faces.
A human can easily tell one face from another, even when the faces belong to strangers. You don't recognize Mom's face because you remember that Mom's nose is 4 cm long, 2.5 cm wide, and has a freckle on the left side! You recognize the whole pattern of Mom's face. There are probably a lot of folks with noses the size and shape of Mom's. But no one has her whole face.
But a computer must have a lot of specific facts about a face to recognize it. Teaching computers to pick Mom's face out of a crowd is one of the hardest things scientists have tried to do yet with computers. But babies do it naturally!
So computers can't think in the same way that people do. But what they do, they do excellently well and very, very fast.