Basics of Computers

1 | P a g e Priyanka Biswas


Basics of computers:

A BRIEF COMPUTER HISTORY

The computer as we know it today had its beginning with a 19th century English mathematics professor name Charles Babbage. He designed the Analytical Engine and it was this design that the basic framework of the computers of today are based on.

Generally speaking, computers can be classified into three generations. Each generation lasted for a certain period of time, and each gave us either a new and improved computer or an improvement to the existing computer.

First generation: 1937 1946 - In 1937 the first electronic digital computer was built by Dr. John V. Atanasoff and Clifford Berry. It was called the Atanasoff-Berry Computer (ABC). In 1943 an electronic computer name the Colossus was built for the military. Other developments continued until in 1946 the first general purpose digital computer, the Electronic Numerical Integrator and Computer (ENIAC) was built. It is said that this computer weighed 30 tons, and had 18,000 vacuum tubes which was used for processing. When this computer was turned on for the first time lights dim in sections of Philadelphia. Computers of this generation could only perform single task, and they had no operating system.

Second generation: 1947 1962 - This generation of computers used transistors instead of vacuum tubes which were more reliable. In 1951 the first computer for commercial use was introduced to the public; the Universal Automatic Computer (UNIVAC 1). In 1953 the International Business Machine (IBM) 650 and 700 series

computers made their mark in the computer world. During this generation of computers over 100 computer programming languages were developed, computers had memory and operating systems. Storage media such as tape and disk were in use also were printers for output.

Third generation: 1963 - present - The invention of integrated circuit brought us the third generation of computers. With this invention computers became smaller, more powerful more reliable and they are able to run many different programs at the same time. In1980 Microsoft Disk Operating System (MS-Dos) was born and in 1981 IBM introduced the personal computer (PC) for home and office use. Three years later Apple gave us the Macintosh computer with its icon driven interface and the 90s gave us Windows operating system.

As a result of the various improvements to the development of the computer we have seen the computer being used in all areas of life. It is a very useful tool that will continue to experience new development as time passes.

Fundamentals:

A computer is an electronic machine that accepts data, stores and processes data into information. The computer is able to work because there are instructions in its memory directing it.

The parts of the computer that you can see and touch, such as the keyboard, monitor and the mouse are called hardware. The instructions that direct the computer are called software or computer program.

Data which is raw facts that you the user enter into the computer is called input. This includes; words, numbers, sound and


pictures. When the data is entered into the computer, the computer processes the data to produce information which is output. For example, you enter 2+2 into the computer as data, the computer processes it and the result is 4 which is information.

Computers are usually categories into three general categories:

1. Supercomputer The fastest, largest, most powerful and most expensive computer.

2. Mainframe Computer This is a little smaller and less powerful than the supercomputer, but, like the supercomputer it is also expensive.

3. Personal Computer (PC) - This is the computer that most people use in their daily lives. This computer is much smaller, less powerful and less expensive than the supercomputer and the mainframe computer. There are two main types of personal computers. Macintosh (Macs) and the PC compatibles (PC). The main differences between the two are the operating systems and the processor they use. This category of computer has two additional types of computers. These are mobile computer and handheld computer. The most popular type of mobile computer is the notebook or laptop computer, and the handheld computer is a very small PC that you can hold in your hand.

Parts of Computer:

The basic parts of a desktop computer are the

computer case, monitor, keyboard, mouse,

and power cord. Each part plays an important

role whenever you use a computer.

Computer case

The computer case is the metal and plastic box that contains the main components of the computer. It houses the motherboard, central processing unit (CPU), power supply, and more.

Computer cases come in different shapes and sizes. A desktop case lies flat on a desk, and the monitor usually sits on top of it. A tower case is tall and sits next to the monitor or on the floor. The front of the case usually has an on/off switch and one or more optical drives.

Monitor

The monitor works with a video card, located inside the computer case, to display images and text on the screen. Newer monitors usually have LCD (liquid crystal display) or LED (light-emitting diode) displays. These can be made very thin, and they are often called flat-panel displays. Older monitors use CRT (cathode ray tube)


displays. CRT monitors are much larger and heavier, and they take up more desk space.

Most monitors have control buttons that allow you to change your monitor's display settings, and some monitors also have built-in speakers.

LED displays are actually LCDs that are backlit with light-emitting diodes. This allows for greater contrast than a traditional LCD.

Power cord

The power cord is the link between the power outlet and the power supply unit in the computer casing. If the power cord is not plugged in, the computer will not power on. To protect your computer from voltage spikes, you can plug the power cord in to a surge protector. You can also use an uninterruptable power supply (UPS), which acts as a surge protector and provides temporary power if there is a blackout.

Keyboard

The keyboard is one of the primary ways we communicate with the computer and enter data. There are many different types of

computer keyboards, including wired, wireless, ergonomic, and multimedia. Although there may be differences in the location of some keys or features, keyboards are very similar and allow you to accomplish basically the same tasks

Escape Key

The Escape (Esc) key allows you to stop a function or action. For example, if a webpage is taking a long time to load, you can press the Escape key to stop loading it.

Function Keys

The function keys are labeled F1 through F12. Some programs use these keys as shortcuts for common tasks. For example, in many programs, F1 opens the Help file.

On some keyboards, the function keys also control things like the sound volume or monitor brightness.

Print Screen, Scroll Lock, & Pause/Break

The Print Screen, Scroll Lock, and Pause/Break keys are at the top-right corner of the keyboard. The Print Screen key takes a picture of your screen (called a screenshot) that you can edit or save using a graphics program. Scroll Lock and Pause/Break are rarely used today, so some keyboards don't have them.


Tab

The Tab key is used to create indents in word processing programs. Also, if you are filling out a form online, you can use the Tab key to switch to the next field.

Alphanumeric Keys

The main part of the keyboard includes the alphanumeric keys (letters and numbers) and the spacebar.

Backspace

The Backspace key erases the character to the left of the cursor.

Cursor Control Keys

The cursor control keys can vary, but they will usually include the following:

Delete: This erases the character to the right of the cursor.

Insert: This switches between insert mode (which inserts new text without deleting anything) and overtype mode (which deletes text after the cursor as you type).

Home and End: These move the cursor to the beginning or end of the current line.

Page Up and Page Down: These scroll a document or webpage up or down.

Ctrl, Alt, and Shift

The Control (Ctrl), Alternate (Alt), and Shift keys are designed to work in combination with other keys. Typically, you hold down Ctrl, Alt, or Shift and then type another key to perform a specific task. For example, in many programs, typing Ctrl+S will save a file.

Keyboards that are designed for Macs have a Command key, which is often used instead of the Control key.

Enter

The Enter key carries out commands. For example, while on the Internet, you can type a website address and then press Enter to go to the site. It is also used to start a new line in word processing programs.


Arrow Keys

The arrow keys are used for many different purposes, including moving the cursor, scrolling a document, and controlling a game.

Numeric Keypad

The numeric keypad resembles a calculator keypad. Many users find that it is easier to type numbers using this keypad. On some keyboards, these keys double as arrow keys.

Mouse

The mouse is a peripheral that is known as a pointing device. It lets you point to objects on the screen, click on them, and move them.

There are two main types of mice: optical and mechanical. The optical mouse uses an electronic eye to detect movement and is easier to clean. The mechanical mouse uses a rolling ball to detect movement. Generally, a mechanical mouse is less expensive, although it may require regular cleaning to keep it working properly.

Traditionally, a mouse connects to the computer using a USB or PS/2 connection. However, you can also buy a wireless mouse, which can reduce clutter on your desktop.

Mouse alternatives

There are other devices that can do the same thing as a mouse but that have a different look and feel. Many people find them to be easier to use, and they also require less desk space than a mouse. The most common mouse alternatives include:


Trackball: A trackball has a ball on top that can rotate freely. Instead of moving the device like a mouse, you can roll the ball with your fingers to move the pointer. Some mobile devices have miniature trackballs that can be controlled with your thumb.

Touchpad: A touchpadalso called a trackpadis a touch-sensitive pad that lets you control the pointer by making a drawing motion with your finger. Touchpads are common on laptop computers.

Input & Output devices:

A computer is an electronic machine that

processes data. Information given to the

computer is called data. Computer works very

fast. It saves your time and energy. It does not

make mistakes. It can remember a lot of things.

The basic parts of a computer are shown in the

picture given here.

The basic input and output parts of a

computer system are:

1. Monitor 2. CPU (Central Processing Unit) 3. Keyboard 4. Mouse 5. Speakers 6. Printer

Input Devices:

Devices that help us put data into the computer are called input devices. They help in giving instructions to the computer. Let us learn about a few input devices.

Keyboard: The keyboard is used for entering data into the computer system. It can type words, numbers and symbols.

Mouse: The mouse is a pointing device. You can give input to the computer with the help of the mouse.


Joystick:

A joystick makes computer games a lot more fun. When it is moved, it passes information to the computer.

Microphone:

A microphone is the mike that can be attached to a computer. It allows you to input sounds like speech and songs into the computer. You can record your voice with the help of a microphone.

Web Camera:

A web camera is used to take live photos videos.

You can save them in the computer.

Scanner:

A Scanner Copies pictures and pages, and turns them into images that can be saved on a computer.

Processing Device:

All the inputs are stored, sorted, arranged and changed by a computer. The device that helps a computer do so is called the processing device. The processing device in a computer is known as Central Processing Unit (CPU).

Output Devices:

The parts of a computer that help us to show the results of processing are called out devices. Let us learn about a few output devices.


Monitor:

A monitor looks like a TV screen. It shows whatever you type on the keyboard or draw with the mouse.

Printer:

A printer prints the results of your work from the computer screen on a sheet of paper. This is called a printout.

Speakers:

The speakers are the output devices that produce different types of sounds processed by the computer. You can listen to songs or speeches stored in the computer with the help of speakers.

Headphone:

You can listen to music or any sound from a computer with the help of headphones without disturbing others.

Storage Devices:

The parts of a computer which are used for storing data are called. Storing data are called storage devices. They help in storing any work done on a computer permanently. Let us learn about a few storage devices.

Hard Disk:

Inside the CPU there is a hard disk. It is made up of one or more metallic disks. It stores a large amount of information.

Floppy Disk:


A floppy disk stores small amounts small amounts of information. It works when it is inserted into the floppy drive. The floppy drive is fixed in the CPU.

Compact

Disc (CD):

A CD stores many times more information than a floppy disk. It works when it is inserted into the CD drive. The CD drive is fixed in the CPU. Note: Not handling the CD properly may result in loss of data stored.

CPU (Central Processing device):

The system unit, like the one above is the case that contains all the electronic components of any computer system. The electronic components are considered internal hardware seeing that they are inside the system unit and you cannot see when you look at the computer. These components inside the system unit are what process the data and really makes the

computer work. Internal components are as follow:

Power Supply: The power supply converts electricity into the current works for the computer. When the computer is turned on the power supply allows converted electricity to travel to other components inside the computer.

Motherboard: The motherboard is the circuit board that holds the main internal components of the computer together. On the motherboard there are three major cards; sound card that operates the sound, the video card that handles the graphics that you see on the monitor and the modem card which allows computers to communicate with each other. Also on the motherboard is the Central Processing Unit (CPU), processor or brain of the computer. The CPU controls information and tells the other components inside the computer what to do.

RAM & ROM: RAM stands for random access memory. This memory holds the information you are working with while the computer is turned on. Once you turn the computer off all the information that was in RAM will be gone. ROM stands for read only memory. This memory holds information that you can only read, but not erase. Information in ROM is built in and is always there even when the computer is turned off.

Disk Drives: The disk drive is the device that reads information that is on disk. Generally speaking most computers have three disk drives; hard disk drive, floppy disk drive and CD-Rom drive. However, there computers that have DVD-Rom drive. While the hard disk is hidden inside the computer the floppy and CD-Rom drives are accessible from the front of the system unit.

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Priyanka

Memory concept:

Memory Units: 4 bit = 1 nibble 8 bit = 1 byte 1024 B = 1 KB (Kilo Byte) 1024 KB = 1 MB (Mega Byte)1024 MB = 1 GB (Giga Byte)1024 GB = 1 TB (Tera Byte)1024 TB = 1 PB (Peta Byte)1024 PB = 1 XB (Exa Byte)1024 XB = 1 ZB (Zeta Byte)1024 ZB = 1 YB (Yota Byte)bit < Byte < KB < MB < GB < TB < PB < XB < ZB < YB bit (b) Byte (B) Mbps mega bits per sec. MBps mega Bytes per sec. The information you put into the computer is called Data Information of a computer is stored as Digital Data A number system defines a set of values that is used to represent Quantity

Priyanka Biswas

= 1 MB (Mega Byte) = 1 GB (Giga Byte) = 1 TB (Tera Byte) = 1 PB (Peta Byte) = 1 XB (Exa Byte) = 1 ZB (Zeta Byte)

1 YB (Yota Byte) < Byte < KB < MB < GB < TB < PB <

mega bits per sec. mega Bytes per sec.

The information you put into the computer

Information of a computer is stored as

defines a set of values Quantity


In which number system, the modern computers are operated?

Binary Number System Name the most significant bit, which represent 1 and 0 for a positive number and negative number, respectively. Sign Bit Which coding scheme represents data in a binary form in the computer system? ASCII, EBCDIC and Unicode are the most commonly used codes under this scheme.

Binary Coding Scheme EBCDIC is a 8-Bit code with 256 different representations of characters. It is mainly used in mainframe computers.

EBCDIC stands for Extended Binary Coded Decimal Interchange Code In the Hexadecimal Number System each number represents a power of 16. To represent the decimal numbers, this system uses numbers from 0 to 9 and characters from A to F to represent numbers 10-15, respectively. It is commonly used as a shortcut notation for groups of four binary digits BCD is a method that represents the decimal digits with the help of binary digits. It takes advantage that one decimal numeral can be represented by 4-bit pattern. BCD stands for Binary Coded Decimal This coding system is used to represent the interval storage area of the computers. In this system, every character is represented by a combination of bits. Binary Coding System The Base or Radix of the decimal number system is 10 The arithmetic operations (addition,

subtraction, multiplication and division) performed on the binary numbers is called Binary Arithmetic What is the standard code the computer industry created to represent characters? American Standard Code for Information Interchange (ASCII) ASCII is a code used for standardizing the storage and transfer of information amongst various computing devices. It is required for representing more than 64 characters. At present, the mostly used coding systems are ASCII and EBCDIC Which code is also known as Reflected Code? Gray Code The 7-bit ASCII code is widely used for Two (0 or 1) In the binary language, each letter of the alphabet, each number and each special character is made up of a unique combination of Eight Bits.


Language concept of computer:

In all over the world, language is the source of communication among human beings. Different countries/regions have different languages. Similarly, in order to communicate with the computer user also needs to have a language that should be understood by the computer. For this purpose, different languages are developed for performing different types of work on the computer. Basically, languages are divided into two categories according to their interpretation.

1. Low Level Languages. 2. High Level Languages.

Low Level Languages

Low level computer languages are machine codes or close to it. Computer cannot understand instructions given in high level languages or in English. It can only understand and execute instructions given in the form of machine language i.e. language of 0 and 1. There are two types of low level languages:

Machine Language. Assembly Language

Machine Language: It is the lowest and most elementary level of Programming language and was the first type of programming language to be developed. Machine Language is basically the only language which computer can understand. In fact, a manufacturer designs a computer to obey just one Language, its machine code, which is represented inside the computer by a String of binary digits (bits) 0 and 1. The symbol 0 stands for the absence of Electric pulse and 1 for the presence of an electric pulse. Since a computer is Capable of

recognizing electric signals, therefore, it understands machine Language.

Advantages of Machine Language

i) It makes fast and efficient use of the computer.

ii) It requires no translator to translate the code i.e. Directly understood by the computer

Disadvantages of Machine Language:

i) All operation codes have to be remembered

ii) All memory addresses have to be remembered.

iii) It is hard to amend or find errors in a program written

In the machine language

iv) These languages are machine dependent i.e. a particular

Machine language can be used on only one type of computer

Assembly Language

It was developed to overcome some of the many inconveniences of machine language. This is another low level but a very important language in which operation codes and operands are given in the form of alphanumeric symbols instead of 0s and ls. These alphanumeric symbols will be known as mnemonic codes and can have maximum up to 5 letter combination e.g. ADD for addition, SUB for subtraction, START, LABEL etc. Because of this feature it is also known as Symbolic Programming Language. This language is also very


difficult and needs a lot of practice to master it because very small

English support is given to this language. The language mainly helps in compiler orientations. The instructions of the Assembly language will also be converted to machine codes by language translator to be executed by the computer.

Advantages of Assembly Language

i) It is easier to understand and use as compared to machine language.

ii)It is easy to locate and correct errors.

iii) It is modified easily

Disadvantages of Assembly Language

i) Like machine language it is also machine dependent.

ii) Since it is machine dependent therefore programmer Should have the knowledge of the hardware also.

High Level Languages

High level computer languages give formats close to English language and the purpose of developing high level languages is to enable people to write programs easily and in their own native language environment (English). High-level languages are basically symbolic languages that use English words and/or mathematical symbols rather than mnemonic codes. Each instruction in the high level language is translated into many machine language instructions thus showing one-to-many translation

Types of High Level Languages

Many languages have been developed for achieving different variety of tasks, some are fairly specialized others are quite general purpose.

These are categorized according to their use as

a) Algebraic Formula-Type Processing. These languages are oriented towards the computational procedures for solving mathematical and statistical problem

Examples are

BASIC (Beginners All Purpose Symbolic Instruction Code).

FORTRAN (Formula Translation). PL/I (Programming Language,

Version 1). ALGOL (Algorithmic Language). APL (A Programming Language).

b) Business Data Processing:

These languages emphasize their capabilities for maintaining data processing procedures and files handling problems. Examples are:

COBOL (Common Business Oriented Language).

RPG (Report Program Generator

c) String and List Processing: These are used for string manipulation including search for patterns, inserting and deleting characters. Examples are:

LISP (List Processing). Prolog (Program in Logic).


d)Object Oriented Programming Language

In OOP, the computer program is divided into objects. Examples are:

C++ Java

e) Visual programming language: these are designed for building Windows-based applications Examples are:

Visual Basic Visual Java Visual C

Advantages of High Level Language

Following are the advantages of a high level language:

User-friendly Similar to English with vocabulary

of words and symbols Therefore it is easier to learn. They require less time to write. They are easier to maintain. Problem oriented rather than

'machine' based.

Program written in a high-level language can be translated into many machine language and therefore can run on any computer for which there exists an appropriate translator.

It is independent of the machine on which it is used i.e.Programs developed in high level language can be run on any Computer

Disadvantages of High Level Language

A high-level language has to be translated into the machine language by a translator and thus a price in computer time is paid.

The object code generated by a translator might be inefficient Compared to an equivalent assembly language program

Software concept of Computer:

Software brings life into computer. It is nothing but instructions (or a program) required to run the computer. It guides the hardware how to do this job. A computer is otherwise a general purpose machine. It is software which differentiates among the various kinds of jobs a computer can perform. Software consists of electronics instruction. A specific set of instructions that drive a computer to perform a specific task is called a program. When a computer is using a particular program, it is said to be running or executing that program.

Microsoft, WordPerfect, Ami pro for Windows are few of the Windows- based word processors available in the market. Oracle, Ingres, Informix, Unify are some of the commercially available Rational Database Management System (RDBMS) packages. Auto CAD has been the most famous drafting package and it works on the windows platform. Diagnostic are the programs used to diagnose the problems of your computers. These are very important programs and are able to rectify the problems of your computer to a certain extent by the programmer itself. Typical examples of such programs are Scan Disk,


Smart Dog and Norton Utilities etc. CorelDraw, PowerPoint and Persuasion are the Presentation graphics or business graphics packages which works in the windows environment.

Software categories:

Software can be divided, from a commercial point of view, using two features: the cost and the permission to be modified.

Subdivision cost is

Freeware: Software which is completely costless. The producers of this software are either public institutions such as universities or developers who do it for personal interest or advertisement or private company who do it for dumping reasons. Some examples are Microsoft interenet explorer, Linux operating system.

Shareware: Software which is initially costless but after a certain period the user is asked to pay a fee or delete it; or software which has two versions: a free one, but incomplete or with advertisement banners and a complete advertisement free one, for which the user must pay. The most common example is Winzip compression program.

Commercial: Software for which the user has to pay a license to use it. Common examples are Microsoft windows operating system and Microsoft word.

Private: Software uniquely built, under payment, for a specific customer to fit his needs. Only the customer may use it. A typical example is universitys students-courses professors database system.

Operating system and types of software:

The computer will not work without software. Software also call programs are the instructions that tell the computer what to do and how o do it. The two main categories of software are system software and application software. The system software also called the operating system (OS) actually runs the computer. This software controls all the operations of the computer and its devices. All computers use system software and without the system software the application software will not work. The most common OS on a PC is the Windows operating system and for the Mac computer it would be the Mac operating system.

Application software is a program that allows users to a specific task on the computer. There are a number of different types of application software available to do many of the tasks we do daily. Four examples of common application software and what they are used for are:

Word Processing Application: One word processing program is Microsoft Word. This program allows you to type letters, assignments and do any other written activity on the computer.

Spreadsheet Application: Microsoft Excel is an example of a spreadsheet program. One can use this program to create charts and do calculations.

E-mail Application: Outlook Express is an e-mail program that allows you to receive and send e-mails.

Internet Application: Internet Explorer is a program that allows you to get connected to the Internet and look at Web sites


Basic of MS-DOS:

MS-DOS was the original operating system for (IBM) PC's, and served as the base on top of which Windows was originally written. MS-DOS provided a text-based 'command-line interface' instead of the visual interface of the Mac and Windows.

Internal command:

An internal command is an MS-DOS command that is stored in the system memory and loaded from the command.com. The illustration shows how commands contained within command.com are part of the command.com file. However, with the external commands, each of the commands is their own separate files.

Below are examples of internal commands in MS-DOS and the Windows command line currently listed in the Computer Hope database.

Assoc Atmadm Break Call CD Chdir Cls Color Copy Ctty Date Del Dir Drivparm Echo Endlocal Erase Exit

For Goto If LH Loadhigh Lock Md Mkdir Mklink Move Path Pause Popd Prompt Pushd

Rd Ren Rename Rmdir Set Setlocal Shift Start Switches Time Title Type

Unlock Ver Verify Vol

External command:

An external command is an MS-DOS command that is not included in command.com. External commands are commonly external either because they require large requirements or are not commonly used commands. The illustration shows each of the external commands are their own separate files. However, the internal commands are all included in the command.com file.

Below are examples of MS-DOS and Windows command line external commands currently listed on Computer Hope.

Append Arp Assign At Attrib Backup Bcdedit Bootsect Cacls Chcp Chkdsk Chkntfs Choice Cipher Comp Compact Convert Debug Defrag Delpart Deltree DiskcompDiskcopy Doskey Dosshell Dumpchk

Edit Edlin Expand Extract Fasthelp Fc Fciv Fdisk Find Forfiles Format FTP Gpupdate Graftabl Help Hostname Ipconfig Label Loadfix logoff Mem Mode More Msav MsbackupMscdex Mscdexnt

MwbackupMsd Nbtstat Net Netsh Netstat Nlsfunc Nslookup Pathping Ping Power Print Reg Robocopy Route Runas Scandisk Scanreg Setver Sfc Share Shutdown Smartdrv Sort Subst Sys

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How to use MS-DOS on your computer(7 steps) ?

1

If you're on a computer that has DOS as an operating system, the command prompt should appear automatically when the computer is turned on.using a Windows computer, you'll need to start the command prompt manually. For most computers, it should be located under

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DOS on your computer(7

If you're on a computer that has DOS as an operating system, the command prompt should appear automatically when the computer is turned on. If you're using a Windows computer, you'll need to start the command prompt manually. For

s, it should be located under

'Accessories' in the Start menu. It can also be accessed by typing "" and "R". Then type in "cmd" without the quotes and you should be in DOS, also known as a Command Prompt.

2

You should see a window with "C:\DOCUMENTS AND SETTINGSname]>", or something similar. This is called the command promptserves the useful purpose of showing what directory you're currently in. At the end of this prompt, you type commands (think verbs) followed by arguments (think nouns - when the verb needs a noun, that is), then press enter. Here are some sacommands:

Priyanka Biswas

'Accessories' in the Start menu. It can also be accessed by typing "" and "R". Then type in "cmd" without the quotes and you should be in DOS, also known as a Command Prompt.

You should see a window with "C:\>", DOCUMENTS AND SETTINGS\[your

name]>", or something similar. This is command prompt, and it also

serves the useful purpose of showing what directory you're currently in. At the end of this prompt, you type commands (think verbs) followed by arguments (think nouns -

a noun, that is), then press enter. Here are some sample


C:\GAMES>ping nosound

C:\MY DOCUMENTS>edit essay.txt

3

The most important thing you should be

able to do is list the contents of

directories, and navigate them. Use the dir

command to list the contents of your hard

disk or the directory (or "folder") that you're

in. Depending on where you are, you might

get something like this:

. DIR

.. DIR

DOS DIR

GAMES DIR

WINDOWS DIR

AUTOEXEC .BAT

ESSAY .TXT

4

When used on its own, dir will show the

contents of your current directory, but

there are many useful arguments for the

dir command. For example, typing the

name of a directory after dir will give you

the contents of that directory instead, and /p

is useful for very long lists because it will

stop and wait for you to press a key every

time it reaches the end of the screen. /p can


also be used in most other commands that

print on the screen.

5

If you want to enter a directory, type cd,

then the path and name of the directory

(ex. cd C:\GAMES\GRAPE). If the directory

is a subdirectory of the directory you're

currently in, like if you were already in

GAMES in the previous example, you could

also just type cd GRAPE. Here, ' cd ' is the

command and the directory is the argument.

The command prompt also shows the name

of your current directory. So, typing

C:\> CD C:\GAMES\GRAPE

Would change the command prompt

to C:\GAMES\GRAPE>

6

Executing programs is exactly like

commands. For example, if I wanted to start

the game Mortar Mayhem, I would navigate

to the directory it's in:

C:\> cd games\mortar

Then type the name of the EXE file, without

the extension.


C:\GAMES\MORTAR> mortar

And the game will run

7 Now that you know the basic syntax of DOS, here are some other useful commands. The things in [brackets] are only examples.

del [countdown.txt] - Deletes a file. Does not remove directories, but does clear their contents.


move [countdown.txt] [c:\games\grape] - Moves a file or folder

md [grape] - Creates a subdirectory


rmdir [grape] - Removes a directory.


Concept of WWW:

What is Internet?

The Internet is essentially a global network

of computing resources. You can think

about the Internet as a physical collection of

routers and circuits as a set of shared

resources or even as an attitude about

interconnecting and intercommunication.

Some common definitions given in the past

include:

A network of networks based on the

TCP/IP communications protocol.

A community of people who use and

develop those networks.

A community of people who use and

develop those networks.

Internet Based Services:

Some of the basic services available to

Internet users are:

Email: A fast, easy, and inexpensive

way to communicate with other

Internet users around the world.

Telnet: Allows a user to log into a

remote computer as though it were a

local system.

FTP: Allows a user to transfer

virtually every kind of file that can

be stored on a computer from one

Internet-connected computer to

another.

Usenetnews: A distributed bulletin

board that offers a combination news

and discussion service on thousands

of topics.

World Wide Web (WWW): A

hypertext interface to Internet

information resources.

What is WWW?

This stands for World Wide Web. A

technical definition of the World Wide Web

is : all the resources and users on the

Internet that are using the Hypertext

Transfer Protocol (HTTP).

A broader definition comes from the

organization that Web inventor Tim

Berners-Lee helped found, the World Wide

Web Consortium (W3C):

The World Wide Web is the universe of

network-accessible information, an

embodiment of human knowledge.

In simple terms, The World Wide Web is a

way of exchanging information between

computers on the Internet, tying them

together into a vast collection of interactive

multimedia resources.

What is HTTP?

This stands for HyperText Transfer

Protocol. This is the protocol being used to

transfer hypertext documents thats makes

the World World Wide possible.

A standard web address such as

http://www.yahoo.com/ is called a URL and

here the prefix http indicates its protocol

What is URL?

URL stands for Uniform Resource Locator,

and is used to specify addresses on the

World Wide Web. A URL is the

fundamental network identification for any


resource connected to the web (e.g.,

hypertext pages, images, and sound files).

A URL will have the following format:

protocol://hostname/other_information

The protocol specifies how information

from the link is transferred. The protocol

used for web resources is HyperText

Transfer Protocol (HTTP). Other protocols

compatible with most web browsers include

FTP, telnet, newsgroups, and Gopher.

The protocol is followed by a colon, two

slashes, and then the domain name. The

domain name is the computer on which the

resource is located.

Links to particular files or subdirectories

may be further specified after the domain

name. The directory names are separated by

single forward slashes.

What is Website?

Currently you are on our website

http://www.tutorialspoint.com which is a

collection of various pages written in HTML

markup language. This is a location on the

web where people can find tutorials on latest

technologies. Similar way there are millions

of websites available on the web.

Each page available on the Website is called

a web page and first page of any web site is

called home page for that site.

What is Web Server?

Every Web site sits on a computer known as

a Web server. This server is always

connected to the internet. Every Web server

that is connected to the Internet is given a

unique address made up of a series of four

numbers between 0 and 256 separated by

periods.for example, 68.178.157.132 or

68.122.35.127.

When you register a Web address, also

known as a domain name, such as

tutorialspoint.com you have to specify the IP

address of the Web server that will host the

site.

We will see different type of Web servers in

a separate chapter.

What is Web Browser?

Web Browsers are software installed on

your PC. To access the Web you need a web

browsers, such as Netscape Navigator,

Microsoft Internet Explorer or Mozilla

Firefox.

Currently you must be using any sort of

Web browser while you are naviating

through my site tutorialspoint.com. On the

Web, when you navigate through pages of

information this is commonly known as

browsing or surfing.

We will see different type of Web browsers

in a separate chapter.

What is SMTP Server?

This stands for Simple Mail Transfer

Protocol Server. This server takes care of

delivering emails from one server to another

server. When you send an email to an email

address, it is delivered to its recipient by a

SMTP Server.


What is ISP?

This stands for Internet Service Provider.

They are the companies who provide you

service in terms of internet connection to

connect to the internet.

You will buy space on a Web Server from

any Internet Service Provider. This space

will be used to host your Web site.

What is HTML?

This stands for HyperText Markup

Language. This is the language in which we

write web pages for any Website. Even the

page you are reading right now is written in

HTML.

This is a subset of Standard Generalized

Mark-Up Language (SGML) for electronic

publishing, the specific standard used for the

World Wide Web.

What is Hyperlink?

A hyperlink or simply a link is a selectable

element in an electronic document that

serves as an access point to other electronic

resources. Typically, you click the hyperlink

to access the linked resource. Familiar

hyperlinks include buttons, icons, image

maps, and clickable text links.

What is DNS ?

DNS stands for Domain Name System.

When someone types in your domain name,

www.example.com, your browser will ask

the Domain Name System to find the IP that

hosts your site. When you register your

domain name, your IP address should be put

in a DNS along with your domain name.

Without doing it your domain name will not

be functioning properly.

What is W3C?

This stands for World Wide Web

Consortium which is an international

consortium of companies involved with the

Internet and the Web.

The W3C was founded in 1994 by Tim

Berners-Lee, the original architect of the

World Wide Web. The organization's

purpose is to develop open standards so that

the Web evolves in a single direction rather

than being splintered among competing

factions. The W3C is the chief standards

body for HTTP and HTML.

Concept of Virus:

A computer virus is a program or piece of

code that is loaded onto your computer

without your knowledge and runs against

your wishes. Viruses can also replicate

themselves. All computer viruses are man-

made. A simple virus that can make a copy

of itself over and over again is relatively

easy to produce. Even such a simple virus is

dangerous because it will quickly use all

available memory and bring the system to a

halt. An even more dangerous type of virus

is one capable of transmitting itself across

networks and bypassing security systems.

Since 1987, when a virus infected

ARPANET, a large network used by the

Defense Department and many universities,

many antivirus programs have become

available. These programs periodically

check your computer system for the best-

known types of viruses.


Some people distinguish between general

viruses and worms. A worm is a special type

of virus that can replicate itself and use

memory, but cannot attach itself to other

programs.

Searching through internet:

Web - Browser Types

Web Browsers are software installed on

your PC. To access the Web you need a web

browser, such as Netscape Navigator,

Microsoft Internet Explorer or Mozilla

Firefox.

Currently you must be using any sort of

Web browser while you are navigating

through my site tutorialspoint.com. On the

Web, when you navigate through pages of

information this is commonly known as web

browsing or web surfing.

There are four leading web browsers:

Explorer, Firefox, Netscape and Safari but

there are many others browsers available.

You might be interested in knowing

Complete Browser Statistics. Now we will

see these browsers in bit more detail.

While developing a site, we should try to

make it compatible to as many browsers as

possible. Especially site should be

compatible to major browsers like Explorer,

Firefox, Netscape, Opera and Safari.

Internet Explorer

Internet Explorer (IE) is a product from software giant Microsoft. This is the most commonly used browser in the universe. This was introduced in 1995 along with Windows 95 launch and it has passed Netscape

popularity in 1998.

You can download latest version of this browser from Miscrosoft site

Netscape

Netscape is one of the original Web browsers. This is what Microsoft designed Internet Explorer to compete against. Netscape and IE comprise the major portion of the browser market. Netscape was introduced in 1994.

Mozilla

Mozilla is an open-source Web browser, designed for standards compliance, performance and portability. The development and testing of the browser is coordinated by providing discussion forums, software engineering tools, releases and bug tracking. Browsers based on Mozilla code is the second largest browser family on the Internet today, representing about 30% of the Internet community.

Konqueror

Konqueror is an Open Source web browser with HTML 4.01 compliance, supporting Java applets, JavaScript, CSS 1, CSS 2.1, as well as Netscape plugins. This works as a file manager as wellIt supports basic file management on local UNIX filesystems, from simple cut/copy

32 | P a g e

and paste operations to advanced remote and local network file browsing.

Firefox

Firefox is a new browser derived from Mozilla. It was released in 2004 and has grown to be the second most popular browser on the Internet.

Safari

Safari is a web browser developed by Apple Inc. and included in Mac OS X. It was first released as a public beta in January 2003. Safari has very good support for latest technologies like XHTML, CSS2 etc.

Opera

Opera is smaller and faster than most other browsers, yet it is fullfeatured. Fast, user-friendly, with keyboard interface, multiple windows, zoom functions, and more. Java and non Java-versions available. Ideal for newcomers to the Internet, school children, handicap and as a frontend for CD-Rom and kiosks.

Lynx

Lynx is a fully-featured World Wide Web browser for users on Unix, VMS, and other platforms running cursor-addressable,

Priyanka

and paste operations to advanced remote and local network file

Firefox is a new browser derived from Mozilla. It was released in 2004 and has grown to be the second most popular browser on the

a web browser developed by Apple Inc. and included in Mac OS X. It was first released as a public beta in January 2003. Safari has very good support for latest technologies like XHTML, CSS2

Opera is smaller and faster than rs, yet it is full-

friendly, with keyboard interface, multiple windows, zoom functions, and

-enabled versions available. Ideal for newcomers to the Internet, school children, handicap and as a front-

om and kiosks.

featured World Wide Web browser for users on Unix, VMS, and other platforms

addressable,

character-cell terminals or emulators.

How to search a matter on internet (Steps

Step 1: when you will open

the desktop page will appear, you will see

some icons on the desktop like these.

Step 2: in the previous picture (Step 1) you

can see the available web browsers on your

computer. You have to search internet by

using these software.

using Internet Explorer

Priyanka Biswas

cell terminals or

How to search a matter on internet (Steps):

Step 1: when you will open computer and

the desktop page will appear, you will see

some icons on the desktop like these.

Step 2: in the previous picture (Step 1) you

can see the available web browsers on your

computer. You have to search internet by

ternet Explorer

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After the double click on the internet

explorer icon a page will open like this.

Now look at the top of the page and you will

find this place called address bar.

Now take you mouse pointer towards this

address bar and click on the text written in

the address bar and you will see the whole

text will be selected and will be highlighted

with blue color. If not then after clicking

anywhere in the text press CTRL+A on your

keyboard.

Now after selecting the whole text and

making all the text blue press backpress

button on your keyboard. It will delete that

address written in the address bar and you

will be able to write of your own choice.

Priyanka

After the double click on the internet

explorer icon a page will open like this.

Now look at the top of the page and you will

find this place called address bar.

Now take you mouse pointer towards this

text written in

the address bar and you will see the whole

text will be selected and will be highlighted

with blue color. If not then after clicking

anywhere in the text press CTRL+A on your

Now after selecting the whole text and

text blue press backpress

button on your keyboard. It will delete that

address written in the address bar and you

will be able to write of your own choice.

Now type in that blank area (any of the

following search engines)

1. www.google.com

2. www.yahoo.com

3. www.bing.com

4. www.ask.com

As google.com is the largest search engine

let us use www.google.com

Then press enter button on your keyboard

after writing.

Now put your mouse pointer in the search

bar situated at the middle of this page.

Priyanka Biswas

Now type in that blank area (any of the

As google.com is the largest search engine

Then press enter button on your keyboard

Now put your mouse pointer in the search

bar situated at the middle of this page.

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Now type the matter you want to search in

the search bar and press enter on your key

board. Let us search computer basic in

google.

It will appear like this (Above picture).

Now choose any of those options written

with blue color and click on any of them and

find if that information is necessary for you.

If not then click the blue arrow situate

the left of the top page and you will find the

above picture page again. Now you can

select any other options too.

Priyanka

Now type the matter you want to search in

the search bar and press enter on your key

us search computer basic in

It will appear like this (Above picture).

Now choose any of those options written

with blue color and click on any of them and

find if that information is necessary for you.

If not then click the blue arrow situated at

the left of the top page and you will find the

above picture page again. Now you can

Now you can use other web browsers like

Google chrome, Mozilla Firefox

same process explained above in case of

internet explorer.

Now special type: You saw we searched

only text but in some time we are in need of

search of some pictures too.

It will appear like this-

Now click on any picture of your choice

it will open in a big view just right click on

the picture and click on the save the picture

as option. It will appear like this

Priyanka Biswas

Now you can use other web browsers like

Firefox just like

same process explained above in case of

Now special type: You saw we searched

only text but in some time we are in need of

search of some pictures too.

Now click on any picture of your choice and

it will open in a big view just right click on

the picture and click on the save the picture

as option. It will appear like this-


Now when you will click save as option it

will appear like this

Documents

Basics of Computers