Class 9 Computer Science Computer Aptitude Notes

SECTION-I : COMPUTER KNOWLEDGE

ABBREVIATIONS

• AAC : Advanced Audio Coding (audio compression format defined by the MPEG-2 standad)
• ABI : Application Binary Interface
• ABR : Area Border Router
• ABR : Available Bit Rate
• AD : Active Directory
• ADC : Analog - To - Digital Converter
• ADC : Apple Display Connector (DVI variant)
• AH : Active Hub
• AHA : Accelerated Hub Architecture
• Ajax : Asynchronous Java Script and XML
• AL : Active Link
• ALGOL : Algorithmic Language
• ALU : Algorithmic and Logical Unit
• AM : Active Monitor
• AMD : Advanced Micro Devices
• AMR : Audio Modem Riser
• AoE : ATA over Ethernet
• APCI : Application- Layer Protocol Control Information
• API : Application Programming Interface
• APIPA : Automatic Private IP Addressing
• ASCH : American Standard Code for Information Interchange
• ASG : Abstract Semantic Graph
• ASP : Application Service Provider
• AST : Abstract Syntax Tree
• ATA : Advanced Technology Attachment
• ATM : Asynchronous Transfer Mode
• AVC : Advanced Video Interleaved
• AWT : Abstract Windowing Toolkit
• BASIC : Beginner's All-Purpose Symbolic Instruction Code
• BCD : Binary Coded Decimal
• BEEP : Blocks Extensible Exchange Protocol
• BER : Bit Error Rate
• BFD : Binary File Descriptor
• BGP : Border Gateway Protocol
• bin : binary
• BINAC : Binary Automatic Computer
• BIOS : Basic Input Output System
• bit : binary digit
• Blob : Binary large object
• Blog : Web Log
• BMP : Basic Multilingual Plane
• BOOTP : Bootstrap Protocol
• BPEL : Business Process Execution Language
• bps : bits per second
• CAD : Computer- Aided Design
• CAE : Computer- Aided Engineering
• CAI : Computer- Aided Instruction
• CAT : Computer- Aided Translation
• CAQ : Computer- Aided Quality Assurance
• cc : C Compiler
• CD : Compact Disc
• CD-R : CD-Recordable
• CD-ROM : CD Read-only Memory
• CD-RW : CD- Rewritable
• CG : Computer Graphics
• CGA : Colour Graphics Array
• CGI : Common Gateway Interface
• CGI : Common -Generated Imagenry
• CIFS : Common Internet Filesystem
• CLI : Command Line Interface
• CLR : Common Language Runtime
• CNC : Computer Numerical Control
• COBOL : Common Business-Oriented Language
• CPU : Central Processing Unit
• CRT : Cathode Ray Tube
• CSI : Common System Interface
• CT : Computerised Tomography
• CTCP : Client-To-Client Protocol
• CTL : Computational Tree Logic
• CTS : Clear To Send
• CUA : Common User Access
• DAC : Digital-To-Analog Converter
• DAP : Directory Access Protocol
• DB : Database
• DBA : Database Administrator
• DBMS : Database Management System
• DCC : Direct Client-to-Client
• DDR : Double Data Rate
• DES : Data Encryption Standard
• DFD : Data Flow Diagram
• DFS : Distributed File System
• DHTML : Dynamic HTML
• DIVX : Digital Video Express
• DLL : Dynamic Link Library
• DLP : Digital Light Processing
• DMA : Direct Memory Access
• DOS : Disk Operating System
• DPI : Dots Per Inch
• DPMI : DOS Protected Mode Interface
• DSL : Digital subscriber Line
• DSL : Domain- Specific Language
• DSN : Database Source Name (ODBC)
• DTE : Data Terminal Equipment
• DTR : Data Terminal Ready
• DVD : Digital Versatile Disc
• DVD : Digital Video Disc
• DVD-R : DVD- Rewritable
• DVI : Digital Visual Interface
• DVR : Digital Video Recorder
• EAP : Extensible Authentication Protocol
• EBCDIC : Extended Binary Coded Decimal Interchange Code
• EDO : Extended Data Out
• EEPROM : Electronically-Erasable Programmable Read-Only Memory
• EFF : Electronic Frontier Foundation
• EFI : Extensible Firmware Interface
• EGA : Enhanced Graphics Array
• EGP : Exterior Gateway Protocal
• eID : electronic ID card
• EIGRP : Enhanced Interior Gateway Routing Protocol
• ELF : Executable and Linkable Format
• ELM : Electronic Mail
• EOM : End of Message
• EPROM : Erasable Programmable Read-Only Memory
• EUC : Extended Unix Code
• EXE : EXEcutable
• FAP : FORTRAN Assembly Program
• FAT : File Allocation Table
• FAQ : Frequently Asked Questions
• FDC : Floppy Disk Controller
• FDD : Floppy Disk Drive
• FIFO : First In Fist Out
• FHS : Filesystem Hierarchy Standard
• FCS : Frame Check Sequence
• FPU : Floating Point Unit
• FS : File System
• FSB : Front Side Bus
• FTP : File Transfer Protocol
• FXP : File eXchange Protocol
• Gb : Gigabit
• GB : Gigabyte
• GCR : Group Code Recording
• GDI : Graphics Device Interface
• GIF : Graphics Interchange Format
• GIGO : Garbage In, Garbage Out
• GPU : Graphics Processing Unit
• GUI : Graphical User Interface
• HAL : Hardware Abstraction Layer
• HCI : Human Computer Interaction
• HDD : Hard Disk Drive
• HD DVD : High Definition DVD
• HDL : Hardware Description Language
• HHD : Hybrid Hard Drive
• HID : Human Interface Guidelines
• HIG : Human Interface Guidelines
• HPFS : High Performance File System
• HSM : Hierarchical Storage Management
• HTM : Hierarchical Temporal Memory
• HTML : Hypertext Markup Language
• HTTP : Hypertext Transfer Protocol
• HTX : Hyper Transport eXpansion
• HURD : Hird of Unix- Replacing Daemons
• HVD : Holographic Versatile Disc
• IBM : International Business Machines
• ICMP : Internet Control Message Protocol
• ICP : Internet Cache Protocol
• IDL : Interface Definition Language
• IE : Internet Explorer
• IGMP : Internet Group Management Protocol
• IGRP : Interior Gateway Routing Protocol
• IHV : Independent Hardware Vendor
• IIOP : Internet Inter-Orb Protocol
• IIS : Internet Information Services
• IM : Instant Messaging
• IMAP : Internet Message Access Protocol
• I/O : Input/Output
• IP : Internet Protocol
• IPC : Inter-Process Communication
• IPP : Internet Printing Protocol
• Ipsec : Internet Protocol security
• IPTV : Internet Protocol Television
• IPX : Internetwork Packet Exchange
• IRC : Internet Relay Chat
• IRP : I/ORequest Packet
• IRQ : Interrupt Request
• ISC : Internet Storm Center
• ISO : International Organisation for Standardisation
• ISOC : Internet Society
• ISP : Internet Service Provider
• ISR : Interrupt Service Routine
• ISV : Independent Software Vendor
• IT : Information Technology
• ITU : International Telecommunication Union
• J2CE : Java 2 Cryptographic Edition
• JDS : Java Desktop System
• JMX : Java Management Extensions
• JMS : Java Message Service
• JNDI : Java Naming and Directory Interface
• JNI : Java Native Interface
• JPEG : Joint Photographic Experts Group
• JS : Java Script
• JSON : Java Script Object Notation
• JSP : Java Server Pages
• JUG : Java Users Group
• Kb : Kilobit
• KB : Kilobyte
• kHz : Kilohertz
• LAN : Local Area Network
• LIFO : Last In first Out
• LSB : Least Significant Bit
• MAN : Metropolitan Area Network
• MANET : Mobile Ad- Hoc Network
• Mb : Megabit
• MB : Megabyte
• MBCS : Multi Byte Character Set
• MBR : Master Boot Record
• MDI : Multiple Document Interface
• MICR : Magnetic Ink Character Recognition
• MIMO : Multiple-Input Multiple-Output
• MIPS : Million Instructions Per Second
• MIME : Multipurpose Internet Mail Extensions
• MMX : Multi-Media Extensions
• MNG : Multiple-Image Network Graphics
• MPEG : Motion Pictures (Coding) Experts Group
• MPL : Mozilla Public License
• MSB : Most Significant Bit
• MS-DOS : Microsoft DOS
• MVS : Multiple Virtual Storage
• NEXT : Near- End Cross Talk
• NFS : Network File System
• NIO : New I/O
• NMI : Non- Maskable Interrupt
• NNTP : Network News Transfer Protocol
• NOP : No Operation
• NOS : Network Operating System
• NT (Windows) : New Technology
• NTP : Network Time Protocol
• OOP : Object- Oriented Programming
• OPML : Outline Processor Markup Language
• OS : Operating System
• OSS : Open- Source Software
• P2P : Peer-To- Peer
• PAN : Personal Area Network
• PAP : Password Authentication Protocol
• PATA : Parallel ATA
• PC : Personal Computer
• PCI : Peripheral Component Interconnect
• PCLe : PCI Express
• PCL : Printer Command Language
• PGA : Pin Grid Array
• PIC : Peripheral Interface Controller
• PIC : Programmable Interrupt Controller
• PINE : Program for Internet News & Email
• PIO : Programmed Input/ Output
• PnP : Plug-and- Play
• PoE : Power over Ethernet
• PPC : Power PC
• PPI : Pixels Per Inch
• PPP : Point-to-Point Protocol
• PPPoA : PPP over Ethernet
• PPTP : Point- to-Point Tunneling Protocol
• PSU : Power Supply Unit
• QDR : Quad Data Rate
• QFP : Quoted For Permanence
• QoS : Quality of Service
• RADIUS : Remote Authentication Dial In User Service
• RAID : Redundant Array of Independent Disks
• RAM : Random Access Memory
• RARP : Reverse Address Resolution Protocol
• RDBMS : Relational Database Management System
• RDF : Resource Description Framework
• REFAL : REcursive Functions Algorithmic Language
• RIP : Routing Information Protocol
• ROM : Read Only Memory
• ROMB : Read-Out Motherboard
• RTOS : Real Time Operating System
• SaaS : Software as a Service
• SAN : Storage Area Network
• SATA : Serial ATA
• SAX : Simple API for XML
• SBP-2 : Serial Bus Protocol 2
• SBU : Standard Build Unit
• SCSI : Small Computer System Interface
• SDL : Simple Direct Media Layer
• SDN : Service Delivery Network
• SDR : Software-Defined Radio
• SDRAM : Synchronous Dynamic Random Access Memory
• SMBIOS : System Management BIOS
• SMTP : Simple Mail Transfer Protocol
• SP : Service Pack
• SPI : Serial Peripheral Interface
• SQL : Structured Query Language
• SUS : Single UNIX Specification
• SVD : Structured VLSI Design
• TCP : Transmission Control Protocol
• TCP/IP : Transmission Control Protocol/Internet Protocol
• TTA : True Tap-Audio
• TTF : True Type Font
• TTS : Text-to-Speech
• TTY : Teletype
• UAC : User Account Control
• UART : Universal Asynchronous Receiver Transmitter
• UEFI : Unified Extensible Firmware Interface
• UI : User Interface
• UL : Upload
• UPS : Uninterruptible Power Supply
• URI : Uniform Resource Identifier
• URN : Uniform Resource Name
• USB : Universal Serial Bus
• Var : variable
• VB : Visual Basic
• VBA : Visual Basic for Applications
• VBS : Visual Basic script
• VFAT : Virtual FAT
• VFS : Virtual File System
• VGA : Video Graphics Array
• VGCT : Video Graphics Character Table
• VLAN : Virtual Local Area Network
• VM : Virtual Memory
• VOD : Video On Demand
• VoIP : Voice over IP
• VPN : Virtual Private Network
• VT : Video Terminal
• WAFS : Wide Area File Services
• WAIS : Wide Area Information Server
• WAN : Wide Area Network
• WAP : Wireless Application Protocol
• Wi-Fi : Wireless Fidelity
• WiMAX : Worldwide Interoperability for Microwave Access
• WInFS : Windows Future Storage
• WINS : Windows Internet Naming Service
• WLAN : Wireless Local Area Network
• WMA : Windows Media Audio
• WMV : Windows Media Video
• WOL : Wake-on-LAN
• WOM : Wake-on-Modem
• WPA : Wi-Fi Protected Access
• WSDL : Web Services Description Language
• WUSB : Wireless Wide Area Network
• WWID : World Wide Identifier
• WWW : World Wide Web
• XAML : eXtensible Application Markup Language
• XHTML : eXtensible Hypertext Markup Language
• XML : eXtensible Markup Language
• XMMS : X Multimedia System
• XNS : Xerox Network Services
• XSL : eXtensible Stylesheet Language
• XSL-FO : eXtensible Stylesheet Language Formatting Objects
• XSLT : eXtensible Stylesheet Language Transformations
• XUL : XML User Interface Language
• Y2K : Year Two Thousand
• ZIFS : Zero Insertion Force Socket
• ZISC : Zero Instruction Set Computer
• ZMA : Zone Multicast Address

IMPORTANT TERMS

Question. Access Time
Answer: Access time is the time from the start of one storage device to the time when the next access can be started.

Question. Accessory
Answer: An Accessory is a device attached to a host computer, but not part of it, and is more or less dependent on the host. It expands the host's capabilities, but does not form part of the core computer architecture. Examples are computer printers, image scanners, tape drives, microphones, loudspeakers, webcams, and digital cameras.

Question. Active Cell
Answer: The cell that continues the value being used or modified in a spreadsheet program, and that is highlighted by the cell pointer. Also known as current cell.

Question. Active Window
Answer: The window in Microsoft Windows with which the user may interact.

Question. Accumulator
Answer: The computer register in which the result of an arithmetic or logic operation is formed (related to arithmetic and logic unit).

Question. Algorithm
Answer: A standard method for computing something; essentially, a mathematical recipe.

Question. Analog
Answer: A continuous waveform signal that can be used to represent such things as sound, temperature, and velocity.

Question. Analog Computer
Answer: A computer in which numerical data are represented by measurable physical variables, such as electrical.

Question. Antivirus
Answer: Computer antivirus refers to a software program that can protect your computer from unwanted viruses and remove any, that penetrate your computer's defenses.

Question. Arithmatic Logic unit (ALU)
Answer: An arithmetic-logic unit (ALU) is the part of a computer processor (CPU) that carries out arithmetic and logic operations on the operands in computer instruction words.

Question. Artificial Intelligence
Answer: Artificial intelligence (AI) is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its chances of success.

Question. ASCII (American Standard Code for Information Interchange)
Answer: ASCII a code for information exchange between computers made by different companies; a string of 7 binary digits represents each character; used in most microcomputers.

Question. Assembly Language
Answer: A programming language that is once removed from a computer's machine language. Machine languages consist entirely of numbers and are almost impossible for humans to read and write. Assembly languages have the same structure and set of commands as machine languages, but they enable a programmer to use names instead of numbers.

Question. Auxilliary Memory
Answer: A high-speed memory bank used in mainframes and supercomputers. It is not directly addressable by the CPU; rather, it functions like a disk. Data are transferred from auxiliary memory to main memory over a high-bandwidth channel.

Question. Backup
Answer: A backup or the process of backing up is making copies of data which may be used to restore the original after a data loss event.

Question. Band Width
Answer: In computer networking and computer science, bandwidth, network bandwidth, data bandwidth or digital bandwidth is a bit rate measure of available or consumed data communication resources expressed in bits/second or multiples of it (kilobits/s, megabits/s etc.).

Question. BIOS
Answer: Basic Input Output System. This is the basic set of instructions that tell the computer how to act. Most computers have these instructions built into a chip that plugs into the motherboard.

Question. Bar Code
Answer: A bar code (often seen as a single word, barcode) is the small image of lines (bars) and spaces that is affixed to retail store items, identification cards, and postal mail to identify a particular product number, person, or location.

Question. Binary
Answer: Computers are based on the binary numbering system, which consists of just two unique numbers, 0 and 1.

Question. Biometric Device
Answer: Biometrics (or biometric authentication) consists of methods for uniquely recognizing humans based upon one or more intrinsic physical or behavioral traits.

Question. Bitmap
Answer: In computer graphics, a bitmap or pixmap is a type of memory organization or image file format used to store digital images.

Question. Blue tooth
Answer: Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances (using short wavelength radio transmissions in the ISM band from 2400-2480 MHz) from fixed and mobile devices, creating personal area networks (PANs) with high levels of security.

Question. Booting
Answer: To boot (as a verb; also "to boot up") a computer is to load an operating system into the computer's main memory or random access memory (RAM).

Question. Browse
Answer: In database systems, browse means to view data. Many database systems support a special browse mode , in which you can flip through fields and records quickly. Usually, you cannot modify data while you are in browse mode.

Question. Bug
Answer: A software bug is the common term used to describe an error, flaw, mistake, failure, or fault in a computer program or system that produces an incorrect or unexpected result, or causes it to behave in unintended ways.

Question. Byte
Answer: Byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits.

Question. CD ROM (Compact Disk- Read Only Memory)
Answer: a type of optical disk capable of storing large amounts of data -- up to 1GB, although the most common size is 650MB (megabytes).

Question. CD-R/W (Compact Disk-Recordable)
Answer: a type of CD disk that enables you to write onto it in multiple sessions. One of the problems with CD-R disks is that you can only write to them once.

Question. Central Processing Unit (CPU)
Answer: The CPU is the computer's control center. Think of it as the brain that does all the thinking (computation), thus it is called the Central Processing Unit. The actual CPU is about 1.5 inches square, yet it is the most critical part of the computer. Having a fast CPU (measured in MegaHertz) greatly aids in the overall speed of your computer.

Question. CMOS
Answer: Acronym " Complimentary Metal Oxide Semiconductor" A CMOS computer circuit consumes very little power and is used in computers to keep track of the system setup information, data, time, type of disk and hard drives, etc, that a computer has in stalled.

Question. Compressed File
Answer: Computer files that have been reduced in size by a compression program. Such programs are available for all computer systems.

Bug: A software bug is the common term used to describe an error, flaw, mistake, failure, or fault in a computer program or system that produces an incorrect or unexpected result, or causes it to behave in unintended ways.

Byte: Byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits.

CD ROM (Compact Disk- Read Only Memory): a type of optical disk capable of storing large amounts of data -- up to 1GB, although the most common size is 650MB (megabytes).

CD-R/W (Compact Disk-Recordable):a type of CD disk that enables you to write onto it in multiple sessions. One of the problems with CD-R disks is that you can only write to them once.

Central Processing Unit (CPU):The CPU is the computer's control center. Think of it as the brain that does all the thinking (computation), thus it is called the Central Processing Unit. The actual CPU is about 1.5 inches square, yet it is the most critical part of the computer. Having a fast CPU (measured in MegaHertz) greatly aids in the overall speed of your computer.

CMOS: Acronym " Complimentary Metal Oxide Semiconductor" A CMOS computer ciruit consumes very little power and is used in computers to keep track of the system setup information, data, time, type of disk and hard drives, etc, that a computer has in stalled.

Compressed File: Computer files that have been reduced in size by a compression program. Such programs are available for all computer systems.

Central Processing Unit (CPU):The Central Processing Unit (CPU) is an electronic component that interprets and carries out the instructions of any application that run on a computer. It is a place where all the computing is done.

Data: Representations of facts. The raw material of information.(Plural of datum.)

Database: The integrated data resource for a computer based information system.

DDR: This is a new type of RAM called Double Data Rate RAM. It is used in some of the newer video cards such as the Nvidia GeForce cards.

Desk Top:The screen in Windows upon which icons, windows, a background, and so on are displayed.

Desk Top Publishing (DTP): Software that allows users to produce near-typeset-quality copy for newsletters, advertisements, and many other printing needs, all from the confines of a microcomputer.

Dial up :A dial-up Internet account allows you to use a computer with a modem and appropriate software to connect to the Internet through an Internet Service Provider (ISP). The software “dials” the ISP’s access numbers and you can then send e-mail, browse the World Wide Web or engage in other Internet activities.

Digital: Terms used to describe any information that has been translated into a corresponding series of is and 0s; any information text, sound, image color, may be digitized.

Digital Computer:A reference to any system based on discrete data, such as the binary nature of computers.

Digital Video/ Versatile Disk (DVD):The successor technology to the CD-ROM that can store up to 10 gigabytes.

Disk: A magnetically encoded storage medium in the form of a plate (also called a platter).

Disk Operating System (DOS): A disk operating system manages disks and other system resources. Sort of a subset of OSes, sort of an archaic term for the same. MS-DOS is the most popular program currently calling itself a DOS. CP/M was the most popular prior to MS-DOS.

Domain Names: A name given to a host computer on the Internet, E-mail names are good examples of domain names (for example bijendra@kbscontent.com).

Downloading:Retrieving a file or group of files from the Internet so that they can be stored on a local hard drive. By accessing this page, you have, in fact, downloaded all the information here so that it can be viewed and interpreted by your web browser.

Electronic Mail:When a message is sent, the message is sent first to the SMTP server, which acts as an "outbox" for users. The message is then relayed to the appropriate mail server, which can be found listed after the @ symbol in the recipient's address. The message then waits on that server until the recipient accesses the message and then deletes it.

Ethernet:A transport method (protocol) used to connect computers to a LAN (Local Area Network) and exchange data.

File: (1) A collection of related records. (2) A named area on a disk-storage device that contains a program or digitized information (text, image, sound, and so on). (3) A component of an overall program or application.

Font: In a simplistic sense, a font can be thought of as the physical description of a character set. While the character set will define what sets of bits map to what letters, numbers, and other symbols, the font will define what each letter, number, and other symbol looks like.

Format:(1) The logical or physical arrangement of the tracks and sectors on a floppy diskette or a hard disk. To be usable, a disk must be formatted so that the tracks and sectors are laid out in a manner compatible with the operating system in use. (2) To prepare a disk or diskette, dividing it into sectors so that it is ready to receive data.

Gigahertz: One gigahertz is equivalent to 1000 megahertz, or 1,000,000,000 hertz.

Hacker:An individual with vast experience with security protocols who attempts to illegally access secure servers in an attempt to download private information, damage systems, or act in some other way to "free information".

Hard Copy: A readable printed copy of computer output.

Hard Disk:Hard disk (internal) is a permanent file and data storage device housed in a computer case.

Hardware:Collective term for any computer-related object that can be kicked or battered.

Hexadecimal Number System:A numeric notation system with a base of 16 decimal frequently used to specify addresses in computer memory. In hexadecimal notation, the decimal numbers 0 through 15 are represented by the decimal digits 0 through 9 and the alphabetic “digits” A through F (A = decimal 10, B = decimal 11, etc.). Can be formed as two 4-bit binary numbers from an 8-bit binary number split into two parts.

GENERAL AWARENESS WITH SPECIAL REFERENCE TO BANKING INDUSTRY

Home Page:The Web page which is the starting point for accessing information at a site or in a particular area.

Host: A computer, attached to a network which provides services to another computer beyond simply storing and forwarding information.

Hyper Text Markup Language: This is the code by which web pages are created so they can be graphically organized in various ways. The web browser downloads the text of the HTML file, and then decodes the text into what you can see here. Many books and online manuals are available to anyone wishing to learn this code.

HTML: Acronym "Hyper Text Mark-up Llanguage" which is used to format information so that it can be structured and made accessible to the World Wide

HTTP: Acronym "Hypertext Transfer protocol" The protocol that forms the basis of World Wide Web technology. HTTP is the set of rules governing the software that transports hyperlinked files along the Internet.

Information Technology (IT): including ICT (Information and Communication Technology) is the application of appropriate (enabling) technologes to information processing.

Input/output (I/O): A generic reference to input and/or output to a computer.

IP: Acronym "Internet Protocol" The standard protocol used by systems communicating across the Internet.

IP Address: A digital code that precisely locates a computer connected to the Internet.

MAC: Short for " Macintosh"; the other type of personal computer, manufactured by Apple Computer

Inkjet Printer:A non-impact printer in which the print head contains independently controlled injection chambers that squirt ink droplets on the paper to form letters and images.

Integrated Services Digital Network (ISDN):A digital telecommunications standard for data delivery over twisted-pair lines with transmission speeds up to 128 Kbps (two 64 Kbps line pairs).

InterFace: (1) A specific hardware or software connection. (2) Making two devices capable of communication. Used most often to refer the design of hardware and software that allows connection of network components and transfer of information.

Internet: Internet is the largest wide area network in the world which links millions of computers. Through internet information can be shared, business can be conducted and research can be done.

IP Address (Internet Protocol Address) :A unique numerical Internet address identifying any piece of equipment hooked up to the Internet (see DNS, dotted quad notation, and IP).

Intranet:An Internet-like network whose scope is restricted to the networks within a particular organization.

Java: Java is a programming language and has a “sandboxed” code interpreter which permits programs to be downloaded to PC’s from the Web, but isolates these applications from access to other applications running on the PC.

JPEG (Joint Photographic Experts Group): A bit-mapped file format that compresses image size.

Jukebox: A storage device for multiple sets of CD-ROMs, tape cartridges, or disk modules enabling ready access to vast amounts of online data.

Key-Board: is one of computer components which used to input data to a computer. It is called an input device.

Laptop: Laptop is small and lightweight computer in which all the main parts fitted into single unit. It is designed to carry it around. Particularly, it is ideal for travelers, journalists, commentators and professionals who want to work both at the office and home.

LCD: Acronym " Liquid Crystal Display" is the technology used for displays in notebook and other smaller computers.

Linux: An open source spinoff of the UNIX operating system that runs on a number of hardware platforms and is made available for free over the Internet.

Local Area Network: Many multiple-computer homes have found ways to link their computers through a central device called a "hub". This way, each computer can share information directly, without the need to transfer data via a portable storage device, like a floppy disk. A properly set up LAN can also permit the connected computers to access the Internet through a single Internet account.

Log on & Log off: Each server that is accessed must have some way to ensure security of their sensitive information. Thus, servers restrict access by forcing users to "log on" with either personal access codes or anonymously. Anonymous access usually requires the individual's e-mail address, and the user's IP address is also logged. Once the desired information has been obtained, the user can "log off", disconnecting access to the server.

Machine Language:Machine language consists of the raw numbers that can be directly understood by a particular processor. Each processor's machine language will be different from other processors' machine language. Although called "machine language", it is not usually what people think of when talking about computer languages. Machine language dressed up with mnemonics to make it a bit more human-readable is called assembly language.

Main Frame Computer:A large computer that can service many users simultaneously in support of enterprise-wide applications.

Memory: One of the essential components of a computer’s central processing unit. Memory is the area where information and programs are actively processed.

Micro Computer:A small computer.

Microprocessor:A computer on a single chip. The central processing component of a microcomputer.

Modem: Modem is a telecommunication device that converts digital signals to analog and vice versa. It is used in dial-up internet connection to connect telephone line to a computer.

Monitor: The high-resolution TV-like tube that displays your computer's output. Today's monitors have much better quality displays than any TV is capable of producing.

Mother Board:is the core of a computer system. It is the circuit board where all other parts connect. It communicates and controls the overall system. No motherboard means no computer system.

MP3 : this stands for "MPEG I Audio Lalyer- 3" and is a digital. compressed music file (these files always end with a mp3). MP3 files are often downloaded or exchanged between people online.

MPEG: Acronym " Motion Picture Experts Group" A video file compression system used on the web.

Mouse: A small, handheld device attached to a computer; when moved across any flat surface (such on the computer screen called a cursor) includes one or more buttons that allow the user to select graphics or text onscreen.

Multimedia application: Computer applications that involve the integration of text, sound, graphics, motion video, and animation.

Multitasking:The concurrent execution of more than one program at a time.

Offline: Pertaining to data that are not accessible by, or hardware devices that are not connected to a networked computer system.

Online: Pertaining to data and/or hardware devices accessible to and under the control of a networked computer system.

Operating Systems or Platform: these terms refer to the software that your computer uses to operate (otherwise known as your OS) and not to a manufacturer or company. Windows 2000, Windows XP, and OSX (Mac) are common platforms.

Online: Connected. You are online if you are working on your computer while it is connected to another computer. Your printer is online if it is connected to your computer and ready to accept data.

Password:Password is a series of characters used to protect resources in a computer from unauthorized access. It is one of the ways to secure computer information from unauthorized users.

Peripherals:A physical device (such as a printer, scanner, or disk subsystem) that is externally attached to a workstation or to the network.

Plugin: A helper application that works within a browser. It adds more functionality to a browser commonly associated with the Netscape Navigator browser software.

Personal Computer:A small computer designed to use by an individual, A microcomputer.

Procesor: The logical component of a computer system that interprets and executes program instructions.

Program:(1) Computer instructions structured and ordered in a manner that, when executed, causes a computer to perform a particular function. (2) The act of producing computer software to perform some application.

Programming: The act of writing a computer program.

Programming language: A language programmers use to communicate instructions to a computer.

RAM: Acronym "Random Access Memory" Random Access memory. the computer's "short term" memory used whenever an action is performed by a program. It is also called the "active memory". RAM is what the computer used to run all applications. RAM is usually specified in Megabites or MB. (The other kind of memory dealers refer to is "storage" memory or hard drive size. it usually is specified in Giga bytes or GB.)

ROM: Acronym "Read Only Memory". in which information is saved once and can never be altered For example. CD-ROM drives read information saved on compact disks (CD's). A CD ROM drive can read that information, but cannot make changes to it. for that you need a CD- RW drive. Some ROM is built into your computer to help it get started when you turn it on.

Scanner: A scanner is a piece of hardware that will examine a picture and produce a computer file that represents what it sees. A digital camera is a related device. Each has its own limitations.

Search Engine: A tool used which matches key words you enter with titles and description on the Internet. It then displays the matches allowing you to easily locate a subject. Similar to a card catalog, but not as efficient. Common search engines are Webcrawler, Yahoo, Alta Vista, Infoseek, and Lycos.

Server: A computer or its software that "serves" other computers by administering network files and network operations. Three types of Internet servers are Web servers, e-mail servers, and Gopher servers.

Surfing: The random, atmless exploration of web pages acluved through following links that look interesting within a document

Software: Software is set of instructions developed by programming language which tells a computer what to do.

System software : controls the overall operation of a computer. Some of the activities include managing system memory, controlling system resources, executing computer hardware functions and interfacing a user with computer hardware and applications.

Unix: UNIX is a family of OSes, each being made by a different company or organization but all offering a very similar look and feel.

Upload: The process of transferring information from one computer to another, generally from a client to a server. For example, you upload a file from your computer to another.

USB: Acronym "Universal Serial Bus" (the plug is very flant and has no pins or pronga). This is a style of port connection that is used by many peripheral devices such as Palm Pilots, phones, scanners, printers etc. This type of connection is much faster than more traditional kind of connections such as serial and parallel ports. Often used by older printers, these port have plugs with little screws attached).

URL: Acronym "Uniform Resource Locator" The specific path to a World Wide Web file, including filename and extension.

UPS: "Uninterruptible Power Supply" An uninterruptible power supply (UPS) is a device that allows your computer to keep running for at least a short time when the primary power source is lost.

Virus: A virus is a program that will seek to duplicate itself in memory and on disks, but in a subtle way that will not immediately be noticed. A computer on the same network as an infected computer or that uses an infected disk (even a floppy) or that downloads and runs an infected program can itself become infected.

WAN: Acronym "Wide Area Network" A larger computer network that is geographically dispersed, such as one that stretched across a university campus.

Web Page: A single screen (document) on a Web site.

Webcasting: "Webcasting" is a term that describes the ability to use the Web to deliver or delayed versions of sound or video broadcasts.

Website: The location of published hypertext content Physically, a Website can occupy an entire Web server or a part of a server; or it can be spread out among different servers as long as its sections are all linked, directly, to the same home page.

WLAN: Acronym "Wireless Local Area Network" in a wireless local area network (WLAN), an access point, is a station that transmits and receives data sometimes refered to as a transceiver).

World Wide Web or WWW:This is the part of the Internet that you are accessing right now. The World Wide Web is so named because each page in the WWW has links to other pages, which have links to other pages, and so on, creating what could visually be seen as a web-like network of links.

Points to remember

• A computer is a data processing machine having two main parts: Hardware and Software.
• Hardware comprises of the physical units of a computer system while software is a set of programs.
• Hardware and software together make a computer system functional.
• Data are raw facts and figures.
• An operating system is an interface between the user and the computer hardware and it manages computer resources.
• An operating system performs different functions and is responsible for process management, file management, etc.
• There are many kind of operating system. Some popular names are:- DOS, UNIX, Windows, Linux, Mac OS, etc.
• The Windows Explorer program is more efficient for viewing folders in Windows.
• Windows Explorer is divided vertically into two parts of two panes. The left side pane displays disk drives and folders in a hierarchical order.while the right pane displays the content of the folder / drive that is selected on left side pane.
• The process of linking text values in a series within a formula is called 'concatenation'.
• A computer is a data processing machine.Data processing involves some activities like data capturing, data manipulation and information management.
• Collection of interrelated data is called a database.
• Computers are very useful for maintaining databases.
• A relational database is a collection of data items arranged as a set of formally described tables from which data can be accessed or reassembled in many different ways without having reorganize the database tables.
• MS Access is a powerful program to create and manage our databases.
• Collection of data about a specific topic is called a table.
• A form is a graphical representation of a table.
• A report is a Presentation of data in a printed form.
• We can create mailing labels for your database using MS Access.
• Internet is the network of computer networks with million of computers attached to it.
• Website are files in servers, which are powerful computers.
• Website contain pages to be known as Web Pages.
• The collection of all websites is known as World Wide Web (WWW).
• Ted Nelson, in 1960s, first coined the term 'Hyper Text'
• Html is a markup language.
• HTML is used to create Web Pages. It uses commands to be known as Tags.
• To compose HTML documents, text editors are used. HTML documents are viewed in Web browser.
• The tools are grouped by type in the Photoshop toolbox.
• Some of the tool icons have a tiny black triangle in the lower right corner of their icons. This means that there are more tools of the same general kind available on a pop up-menu.

What is a computer

20th century saw rapid developments in science and technology influencing every aspect of human life. This period witnessed one of the greatest achievements for human who created 'the Computer'. A computer is an electronic and programmable device that receives input, stores, manipulates and processes data to provide output in a useful format. It is used to solve problems relating to almost all fields such as administration, defence, education, home, medicine, science and technology, research, designing, accounts, publishing etc. No doubts, in recent years, Computer and information Technology (I T), has became an integral part of human life. As computer is an information processing and information-accessing tool ,it accepts some information / data from the outside world, processes those data and produce a new information/data. Hence, information processing is the essence of computing.

Meaning of the word 'Computer': The word computer has its origin from an English word 'Computer', which means 'to calculate'.

Program: Computer is an electronic machine which processes the input information/data as per the given set of instructions that is called program.

Characteristics of Computer

Computer has become an essential part of our day-to-day activities. Computers are used more or less in every sphere of life. Its growing importance, is because of its unique features.

• Accuracy : Computers are very accurate. They do make mistakes but seldom. This is because of their physical circuit. Even if they make mistakes, It might be because of the faulty programs, some mistake made while feeding in the data or poorly designed system. The highly efficient error detecting techniques of the computer prevent its from showing false results.
• Speed : The computer was initially invented as a very high speed calculator. This helped in completing many scientific projects that were previously impossible. The landing on the moon would not have been possible if computer had not been there, neither would we take an umbrella if we saw clear sky and weather forecast told us that it would rain in the afternoon. We would have taken a lot of time in making the arrangements for flying abroad if computers were not there to book our seats so easily and fast. This ability to get the answers fast enough so that one has time to take an action on them (to make alternative arrangements in case of reservations) makes real- time- computing possible. Electrical pulses, so its speed is virtually instantaneous. When talking about speed of the computer, we don't talk in seconds or microseconds but in nanoseconds (\( 10^{-9} \) seconds) or even picoseconds (\( 10^{-12} \) seconds).
• Versatility : This means that the computers are capable of performing any type of task, provided the activity could be put into logial steps. It can be used from cooking (microwave oven) to spending a night on the moon (through satellities). In today's world it is difficult to imagine even a single field which is untouched by computer invation.
• Storage : A human mind acquires some knowiedge and affter it has used, it might keep it in its subconscious mind or might even forget it after some time. But computers can store massive amounts of information. This information can be used and reused time and again for years (unless something goes wrong with the hardware). Today's computers have the disks. which have the capacity of storing billions of characters. This is big enough to store the complete Britanica Theasaurus, dozens of computer programs or the applications, thousands of songs, huge databases, all the projects we have ever done in our life and much more.
• Memory : Sometimes if we try to recall what we studied last year, we are not able to recollect. In case of computer, it's not like that. If we store any information in the computer's memory, it remains there till we do not delete it. Moreover, the memory of computer is unlimited, we can store as long as we want.
• Automation : A computer is much more than just a calculator in which we need to give the instructions at every step. It is an intelligent device and if programmed for an activity, it keeps doing it till it finishes, without any human intervention.
• Diligence: Computer being a machine, does not show any signs of fatigue, tiredness, lack of concentration, or lost interest. The speed, accuracy and the quality would be absolutely same in the first and the last calculation, even if millions of calculations are done by computer. It will not complain even once that they are bored. Thus, it is best specially for monotonous and voluminous work. Although that is a threat for the people who are working on the same kind of jobs.
• Reliability : Above all qualities of the computer make them reliable and also make us too dependent on them. They can be run for years and years without any loss of data or any other problem.

Development of Computer

• 1600 A.D.– NAPIER BONES: Another counting device is Napier Bones, "John Napier. a Scottish Mathematician, invented it. The "bones" were strips of ivory with numbers written in them. When the bones were arranged properly. the user could read the numbers in adjacent columns to get the answer of a multiplication operation.
• 1642 A.D– ADDING MACHINE– BLAISE PASCAL– PRANCE: The well known French Scientist and Mathematician, Blaise pascal invented the first machine which could add, carry digits automatically. he was only nineteen years old at that time. His machine was so revolutionary that the principle behind it is still used in most of the machanical counters being used today.
• 1692 A.D.– MULTIPLYING MACHINE- COTTFRIED LEIBNITZ- GERMANY: Gottfried improved upon Pascal's machine and introduced a mechanism to carry out automatic multiplication of numbers. Leibnita is best known for his work with Sir Isaac Newton in developing a branch of Mathematics, known as Calculus. The calculator in vented by him could add, subtract, multiply and divide accurately. It could even perform square root function, although not always accurately.
• 1813 A.D. – DIFFERENCE ENGINE– CHARLES BABBAGE– ENGLAND: Since early 19th century, Charles Babbage, an Englishman, had been working on the development of a machine, which could perform complex calculations In 1813 A.D. he invented the 'Difference Engine' which could perform complex calculations and print them out as well. This machine was a steam powered machine.
• EARLY 1800'S JACQUARD LOOM- JOSEPH MARIE JACQUARD: In the early nineteenth century, a French weaver Joseph marie Jacquard developed a programmable loom, which used large cards and holes punched in them to control the pattern automatically. The output was a thick rich cloth with repetitive floral or geometric patterns. Jacquard patterns are still produced to this day. Others adapted the punched cards and used as the primary form of input. They were used till about 20 - 25 years ago.

Computer Generations

In recent years, the computer industry has grown at a phenomenal pace. In a short time of 35 years or so computers have improved tremendously. In the last decade the speed of computer has increased 200 times, Not only that the reliability curve has also taken a sharp increase. The cost per unit of calculating has gone down by 500 times. The storage capacity is increasing so fast that now it seems that nothing is impossible to store. Large data can be stored in very small devices. The term "generations" was initially introduced to distinguish between different hardware technologies. Gradually it shifted to both hardware and software as the total systems consists of both of them. The computers can be divided in five past generations, i.e., depending upon the technologies used. The five generations of computer are:

Ist GENERATION (1942-1955)

Until 1951, electronics computers were the exclusive possession of scientists and the military. Till then nobody tried to use them for business purpose. The idea of marketing them was conceived by Mauchy and Eckert, creators of ENIAC's. As US census bureau was already using IBCP cards, they were the pioneers in buying this computer for the first time in 1951. The company created by M and ETS became UNIVAC division of Sperry and Corporation.

• The bringing of first UNIVAC (Universal automatic computers) general purpose electric digital computer, marks the beginning of the first generation of electronic computers. These computers used valves and all the components were joined by copper wires. Due to large size of the components and due to the facts that the components had to be spaced apart as the valves dissipated a lot of heat, the computers were very bulky and required huge electric power, airconditioners, maintenance and space for their installation.
• Computer belonging to this generation had the following characteristics:
  1. Comparatively large in size as compared to present day computers.
  2. Generated lot of heat, they were not consistent and reliable as the valves tended to fail frequently.
  3. Low capacity internal storage.
  4. Individual, non- related models.
  5. Processors operated in the milliseconds speed range.
  6. Internal storage consisted of magnetic drum and relay lines.

2nd GENERATION (1955-1964)

• FGC were very unreliable, mainly because of vacuum tubes which kept on burning out. Users had to be prepared all the time with dozen of extra tubes to replace them. The computers of this generation were charaterized by the use of solid state devices (transistors) instead of vacuum tubes. Transistorizsed circuits were smaller, generated little heat, were less expensive and consumed less power than vacuum tube circuits and were much greater in porcessing capacity.
• Computers of this generation had the following charateristics.
  1. Smaller in size compared to the first generation computers.
  2. Generated a lower level of heat, as components were much smaller.
  3. Greater degree of reliability because of solid state technology.
  4. Higher capcity of internal storage.
  5. Use of core storage instead of magnetic drum and relay lines.

3rd GENERATION (1964-1975)

• A revolution in the computer development took place with the development of integreated circuits (IC) on a single silicon chip. In 1958, Jack St. Clair Kelby and Robert Noyce invented the first IC. IC incorporated number of transistors and electronic circuits on a single wafer or chip of silicon. IC was called chip because of the way they were made. One more technology development which took place was the launching of first telecommunication satellite. The communication stations on the earth were now in a position to send and receive data by means of satellite communications between the computer systems around the world.
• Computers of this generation has the following characteristics:
  1. Smaller in size as compared to second generation computers.
  2. High capacity internal storage.
  3. Remote communication facilities.
  4. Multiprogramming facilities
  5. Wide range of optional peripherals.

4th GENERATION (1975-1989)

• The 1970's marked the beginning of a new generation of computers. the development of microprocessor chip which contains an entire central processing unit (CPU) on a single silicon chip led to the mushroom growth of expensive computers. They were not computers by themselves but they can perform all the functions of arthimatic logic unit and control units of the CPU, memory and input ouput devices, they become microcomputers. The semiconductor memores were also very small and very cheap. There were several types of memory chips. Three of the most commonly used are (a) Random Access Memory (RAM) in which data can be read or written corresponding to the main memory of the conventinal computer. (b) Read Only Memory (ROM) and (c) Programmable Read Only Memory (PROM).

5th GENERATION (1989-Present)

• Till fourth generation of computers, the major stress was on improving the hardware from valves to transistors and then to integrated circuits, which resulted in miniaturization and fast speed of computers. However, the lack of thinking power has forced the scientists to work further for Fifth generation computers. The concept of "Artificial Intelligence" is being used in these computers and Japanese call them "Knowledge Processors".
• The fifith generation has three functional requirements.
  1. Easy to use computers with high intelligence and natural human input and output mechanism.
  2. Reliable and efficient software development by new languages, new computer architectures and systems software which overcome previous problems
  3. Improved overall functions and performance aimed at making computers smaller, lighter, faster of greater capacity. more flexible and more reliable. These are the objectives which set the main themes for the future of computing. whatever techniques are used to achieve them.

Classification of Computers

• Initially computers were clasified on the basis of their size, speed and cost but now there are many more attributes attached to them.
• Each and every computer must fall in one of the four categories described below:
  1. Supercomputer
  2. Mainframe computer
  3. Mini computer
  4. Micro computer

SUPER COMPUTERS : Consider the application where a space shuttle or a satellite launcher has to be controlled. The volume of data involved in these applications is enormous. But, the analysis of this data is to be done in fractions of a second. To

...achieve their performance, some special computers have been built. They are known as Super Computers. In India these types of computers have been installed at weather forecasting departments and other leading research institutions.

MAINFRAME COMPUTER

The mainframes are bigger in size, have vast amount of memory and can handle larger than minicomputers.Apart from that their input/ output operations are very fast. For these reasons. the mainframes are generally used in environments where lot of data has to be processed like banks and research Institutions.

MINI COMPUTER

The Mini computers are slightly bigger in size, memory and speed when compared to Micro computers. The major differences is that the Minicomputer are multi user systems. A multi user system means, more than one user can work in the computer systems at the same time. These computers are generally used for scientific purposes and for small business establishments.

MICROCOMPUTERS

The Microcomputers are mainly used for personal use like word processing. Apart from that, these computer systems are generally used in those applications where there are lot of interaction between the computer and the user is required. Normally, only one user will be able to work on this system at a given time, which is called single user system. (The 16 wire bus) microcomputer, is often called the super- micro, and the 32 wire bus microcomputer is often called as megamicro. But these computers have become common and these are generally known as Micro- Computers).

Computer : The Definition

"Computer is an electronic device for performing arithmetic and logical operations", or "Computer is a device or flexible machine to process data and convert it into information

The Computer Hardware (actual machine) is defined in such a way that it does whatever the Software (computer programs) tells it to do.

There are four basic operations which a computer performs irrespective of the program which is running on it. They are classified as:

• INPUT: This is for the purpose of inserting or feeding data into the computer by means of an input device like keyboard.
• PROCESSING : Some kind of processing is done in the computer to take out or transform the data in some way.
• OUTPUT: The computer produces output on a device, such as printer, scanner or a monitor, that shows the result of processing operations.
• STORAGE: The computer stores the result of processing operations for future use in some storage device like hard disk, compact disk drive (CD Rom) or a floppy disk.

THE INPUT UNIT

The Input Unit provides an interface between the users and the machine, for inputing data and instruction etc. One of the most common examples is the keyboard. Data can be input in many more forms- audio. visual, graphical etc.

Some common input devices are listed below:

• Keyboard
• Mouse
• Voice data entry
• Joystick
• Light pen
• Scanner
• Secondary storage devices such as floppy disks, magnetic tapes etc.

The data in any form is first digitized i.e., converted into binary form, by the input device before being fed to the Central Processing unit (CPU).

THE OUTPUT UNIT

Like the Input Unit, the Output Unit also provides an interface between the user and the machine. A common example is the visual display unit (monitor) of a personal computer. The output unit receives the data from the CPU in the form of binary bits. This is then converted into a desired form (graphical, audio, visual etc.) understandable by the user. Some common output devices. are:

• Visual Display Unit (Monitor)
• Printers
• Speakers

The input and output unit collectively are referred to as 'peripherals'

THE CENTRAL PROCESSING UNIT

The Central processing unit is the brain of the computer system. The input and output devices may vary for different application, but there is only one CPU for a particular computer. The specifications of a computer are basically characterized by its Central Processing Unit.

The central processing unit can be further divided into:

• The Arithmetic Logic Unit (ALU)
• The Control Unit
• Main Memory

The CPU performs many tests, some of which are listed below:

• The CPU can perform arithmetic calculations such as addition, subtraction etc.
• The CPU can perform logical decisions.
• The CPU with the help of other devices can per form data transmission.
• The CPU can perform manipulating tasks such as word processing.
• After performing the required task the CPU may place results in memory of send results to the output device according to the instruction given to it.
• The CPU with the help of its control unit generates timing signals (also known as enable signals) which provide synchronization between the different devices and the CPU.

As mentioned earlier, the central processing unit consists of:

• The Arithmetic Logic Unit (ALU)
• The Control Unit
• The Main Memory Unit

THE ARITHMETIC LOGIC UNIT (ALU)

As the name may indicate the arithmetic logic unit performs all arithmetic and logic calculations on the data it receives.

ARITHMETIC CALCULATIONS

The arithmetic calculations may be addition, subtraction, multiplication, division, exponentiation etc.

THE MAIN MEMORY UNIT

The main memory also known as the primary memory is a part of the central processing unit and is a combination of both RAM (random access memory) and ROM (read only memory).

RAM

The random access memory is read write memory i.e. information can be read as well as written into this type of memory. It is voltile in nature. i.e., the information it contains is lost as soon as the system is shut down unless 'saved' for further usage by users. It is basically used to store programs and data during the computer's operation.

ROM

The read only memory as the name may suggest contains information that can only be read, i.e., you can't write on this type of memory. It is non-volatile or permanent in nature. It is basically used to store permanent programs such as program for the functioning of the monitor.

• Access Mode: which means how easily they are accessible.
• Access time: the average time required to reach a storage location and obtain its content is called access time.
• Transfer Rate: the transfer rate is the number of characters or words that a device can transfer per second after it has been positioned at the beginning of the record.
• Capacity and cost: the capacity and cost may depend upon the requirement and the budget.

The main memory has a very low access time and a very high transfer rate. It is limited in capacity and costlier than secondary storge devices.

COMPUTER HARDWARE

The term computer hardware refers to the various electronic components that are required for you to use a computer along with the hardware components inside the computer case. Computer equipment is made of several common components. These include:

• The main computer box.
• A monitor- Looks like a television screen.
• A keyboard.
• A mouse.
• Speakers
• An optional printer

THE MAIN COMPUTER BOX

The main computer box is made of several computer hardware components and subcomponents which include:

The case: The outside component which provides protection for the parts inside and provids a fan and power supply which are used to both cool the working parts inside and provide power to them.

Input devices: Input devices are pieces of equipment that are used to get information INTO a computer. Such as.

• keyboard
• mouse
• microphone
• joystick
• scanner
• digital camera (still or video)
• thumb drive

Output devices: Output devices are pieces of equipment that are used to get information OUT of a computer. Such as:

• monitor
• printer
• speakers
• projector

• USB: Most cable today are USB. USB cables can have a couple of different connectors. The one given below is the most common type. You will find USB ports in the back or side of your computer. also sometimes on the monitor and keyboard.
• Firewire (IEEE): Firewire is a high speed cable used primarily to transfer video from a digital video camera to a computer and vice versa.
• CPU: The CPU, or Central Processing Unit is the actual computer or brains of the computer. This is where the "computing" takes place.
• Hard Drive: All computers have a hard drive. The hard drive (HD) is where everything is saved. Every program, every file or document is saved on the hard drive.
• RAM (memory): When we talk about the memory of a computer, we are talking about RAM, or Ramdon Access Memory. RAM is your temporary working space, This is where you do your work. but it is temporary. If you don't save your work back to your hard drive, you will lose your work, (this is why when your computer freezes and have to restart, you lose your work)
• Bytes: We us Bytes as unit of measurement used to indicate how much memory information will take up. Bytes is the root word, prefixes are added to it to change it's value:
  (K) kilo = 1000
  (M) mega = million
  (G) giga = billion
  1 KB = 1,000 bytes (approx.)
  1MB = 1,000, 000 (1 million) bytes = 1000 kb (approx.)
  1 GB = 1, 000, 000, 000 (1 billion) bytes = 1, 000 MB (approx.)
  Every letter or number you type takes up 1 byte of space.
• CD ROM: stands for Compact Disk-Read Only Memory, which means you can only read what is on the CD, you can't change or delete it. When something is burned on a disk. it's more or less permanent.
• Floppy Disks : Floppy disk have pretty much become obsolete or out dated. Most people do not use them anymore because they do not hold very much information (1 megabyte) and are not very reliable. There are much better options for such as these other type of media listed here.

Software is a general term which is used to describe the instructions that are given to computer. These instructions can be either a single programme or a group of programmes.

Types of Software

Software is generally classified into theree specific categories in the computer world:

• System software
• Application software
• Utility software

System software

This consists of all the programmes, languages and documentation supplied by the manufacturer of the computer. This type of software is required to use the computer efficiently and conveniently. These programmes allow the application developer to write and develop their own programmes.

Application software

These programmes are developed by the user in order to perform some specific function for the organisation. For example, a payroll system to compute the salaries of the employees of an organisation is termed as an application software.

Utility software

Utility software may be considered as an application software or a system software which is very often used in the development of a programme.

PROGRAMMING LANGUAGES

A programming language consists of words, symbols and usage rules pertaining to the grammar that permits people to communicate with the computer. permits people to communicate with the computer. Understanding of computer software is imperfect with out a basic knowlede of programming languaes, Programming languages allow the programmers and end users to develop the programmes that are exceuted by users to develop the programmes that are executed by the computer. Many programming languages exist in the world today. Each one of the languages have their own unique vocabulary, grammar and usage. Some of these languages have been created to serve a special purpose while others are more flexible and general purpose and are suitable for many types of applications. However ingeneral, programming languages must cater to the following tasks:

• input/ output
• text manipulations/ calculations
• logic/ comparison
• storage/ retrieval

CLASSIFICATION OF PROGRAMMING LANGUAGE

Machine Languages

Machine language is the lowest form of computer language. Programmes were only written in binary based machine level language in the first generation computers. The computer understands this language only at its lowest level.

An instruction perpared in machine language has two parts:

• Op-code: This is the first part and is the command or operation and it tells the computer what function to perform.
• Operand: The second part of the instruction is the operand and it tells the computer where to find or store the data or instructions that are to be manipulated. The number of operands in an instrution varies from computer to computer. In a single operand machine, the binary equivalent of "ADD0481" could cause the value in a storage location 0481 to be added to a value stored in the arithmatic & logic unit. The single operand format is popular in the smallest microcomputers whereas the two operand structure is found in most other machines.

The set of instructions in a machine level language can be divided into four categories:

• Arithmatic – add, subtract, multiply and divide
• Controlled– load, store, jump instructions
• Input output – Read and write
• Direct use – Halt, start and end

No arithmatic or comparison operations are done in the primary memory of the computer. Instead it is done in the ALU's special register called accumulator. Thus if we need to add two numbers, we require one instruction which will order the control unit to place a nuber in the accumulator and another instruction to identify the operation of addition.

Symbolic/ Assembly Languages

In order to reduce the burden, symbolic languages, commonly known as assembly languages was developed in 1950's for the second generation computers.

This language permits the use of symbols or mnemonics which are two or three letter abbreviations for the function to be performed by the instruction. These are then translated by using symbolic equivalence table. to control registers etc. However, the disadvantage of using binary has been removed.

Functions of Assembler

• The Assembler translates the function code into its machine code equivalent.
• It assigns absolute addresses to any symbolic address or label names.
• It places each instruction in central memory.
• It identifies indirect addresses from direct addresses and sets the appropriate bit in the address portion of the instruction.
• It checks the syntax of each instruction and generates error messages.
• It provides, optionally, a cross reference table between all symbolic names and their absolute addresses.
• It informs the control unit to exceute the program after all errors have been corrected.

Advantages of Assembly languages

• They save time and reduce detail as compared to machie language.
• Lesser number of errors are made and errors are easier to detect.
• Assembly programs are easier to modify than machine language programs

Disadvantages of Assembly Language

• Writing a code is time consuming.
• Assembly languages are machine dependent.

High Level Languages

The disadvantages of using assembly language brought about the development of higher level languages. Unlike the assembly programs, high level language programs may be used with little modification. High level languages are easier to learn than symbolic languages. They require less time to write, are easier to maintain, provide better documentation and 4 or 5 low- level in structions are reduced to a single high level statement. Some of the popular high level languages are given in the table below.

• FORTRAN: Formula Translator - Scientific & Engineering
• COBOL: Common Business Oriented Language - Commercial
• ALGOL: Algorithmic Language - Scientific
• RPG: Report Generator - Commerical
• APL: A Programming Language - The Sharing System
• PL/1: Programming Language - The Sharing System
• BASIC: Beginners All Symbolic Instruction Code - Teaching
• PASCAL: Named after the French Philosopher - Teaching

The operating system

The operating system is the core software component of the computer. It performs many functions and is in very basic terms an interface between your computer and the outside world. In the section about hard ware, a computer is described as consisting of several components including your monitor, keyboard, mouse and other parts. The operating system provides an interface to these parts using what is referred to as "drivers". This is why sometimes when you install a new printer or other piece of hardware, you system will ask you to install more software called a driver.

Operating System Types

There are many types of operating systems. The most common is the Microsoft's operating systems. They include from most recent to the oldest:

• Windows XP Professional Edition: A version used by many businesses at workstations. It has the ability to become a member of a corporate domain.
• Windows XP Home Edition: A lower cost version of Windows XP which is for home use only and should not be used in a business.
• Windows 2000: A better version of the Windows NT operating system which works well both at home and as a workstation in a business. It includes technologies which allow hardware to be automatically detected and other enhancements over Windows NT.
• Windows ME: An upgraded version from windows 98 but it has been historically plagued with programming errors which may be frustrating for home users.
• Windows 98: This was produced in two main versions. The first Windows 98 version was plagued with programming errors but the Windows 98 Second Edition which came out later was much better with many errors resolved.
• Windows NT: A version of Windows made specifically for businesses offering better control over work station capabilities to help network administrators.
• Windows 95: The first version of Windows after the older Windows 3.x, versions offering a better in terface and better library functions for programs.

There are other worthwhile types of operating systems not made by Microsoft. The greatest problem with these operating systems lies in the fact that not as many application programs are written for them. However if you can get the type of application programs you are looking for, one of the systems listed below may be a good choice.

• Unix: A system that has been around for many years and it is very stable. It is primarily used as a server rather than a workstation and should not be used by anyone who does not understand the system. It can be difficult to learn, Unix must normally run on a computer made by the same company that produces the software.
• Linux: Linux is similar to Unix in operation but it is free. It also should not be used by anyone who does not understand the system and can be difficult to learn.
• Apple Macintosh: Most recent versions are based on Unix but it has a good graphical interface so it is both stable (does not crash often or have as many to learn). One drawback to this system is that it can only be run on Apple produced hardware.
• Windows XP: An operating system, sometimes called an "OS", is the main program the computer used to function properly. Operating systems act as a link between you, the user, and the programs you use on a computer. Different types of computers use different types of operating systems. The majority of computers used either run Microsoft Windows or MacOS. While files can be shared between these two types of systems. they are generally incompatible.
• Desktop: The desktop is the area you see when the computer is not running applications. It consists of the icons on top of it. as well as the Start bution and other features. The desktop can be used to temporary store information or to move around documents and windows.
• Icon: Icons are little pictures that represent different programs or saved items. Double- clicking on the Icon accesses the information represent.
• Window: Each application opened will appear in its own window. or its own little section of the screen. Windows can be moved and resized so that you can operate many different applications at the same time. To learn how to manipulate windows, refer to the Manipulating Windows portion of Level.
• Dialogue Box: When you ask the computer to act on certain commands, as to save your work, the computer will need more information from you. and this will appear in a dialogue box. These boxes contain options and commands for computers to execute.

• Start Menu: In the lower left- hand corner of the Windows screen is the Start button. When you click on the button, a menu will appear, which we will call the Start menu. This menu gives you access to all the different parts and functions of the computer.
• Task Bar: At the very bottom of the screen is a horizontal bar called the task bar. This bar contains (From left to right) the Start button, shortcuts to various programs, minimized programs, and another section of shortcuts that includes sound, volume, printers and the time.
• The Internet: the world Wide Web, or the Web are all names used to describe the vast network of information in cyberspace, available to anyone who has access to a computer, a browser (software), and a connection to an Internet service provider through a modem (or other connection such as DSL, ISDN, LAN etc). Many people use the terms Internet and World Wide Web (a. k. a. the Web) Interchangeably, but in fact the two terms are not synonymous. The Internet and the Web are two separate but related things.
  The Internet is a massive network of networks, i.e. a networking infrastructure. It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they both are connected to the Internet.
• BLOG: A Blog, short for weblog, is usually a personal, time stamped, online journal that apperars on a website. It can be periodically updated by the owner. sometimes called a blogger. Many sites of fer free software to create blogs on personal websites.
• Downloading: is when you take a file from some one else's computer and put it on your own. A file can be anything from a pretty picture to the enitre text of the Declaration of Independence.
• E- mail: is the more common abbreviation for Electronic mail. It allows computer users locally and worldwide to exchange messages. Each user of e-mail has a mailbox address to which messages are sent
• Internet Service Provider (ISP): It connects you to the Internet.
• Search Engines/ Search Directories: a search engine is a searchable database of Internet files collected by a computer program (this program is sometimes called a wanderer, crawler, robot, worm, spider, etc) An index is created for the collected files. e,g., title, full text, size, URL, etc. There is often no selection criteria for these collection of files, except a ranking of "best fit" results.
• URL: stands for Uniform Resource Locator. The URL specifies the internet address of a file stored on a host computer connected to the Internet. Every file on the Internet, no matter what its accessing protocol, has a unique URL, Each web site must have its own specific address, similar to the way, each home must have a unique address in order to receive mail delivery service.
• Web Browser: a web browser is a software, installed on your computer, that allows you to navigate. Internet Netscape Navigator and Microsoft Internet Explorer are two of the most commonly used web browsers.
• Web Site: contains all the information offered by a particular organization, individual, or company and will sometimes include links to other sites as well. Each web site generally starts with a home page and then links to other pages within the site containing various types of information and/ or services/ products. A website can be made up of a single webpage document or hundreds/ thousands, limited only by the size restrictions of the webserver it is housed in.
• Menu Bar: Contains menu items that open up dropdown lists for related options. Among the items are options for printing, customizing IE, copying and pasting text, managing Favourites, and accessing Help.
• Navigation Toolbar: Contains icons for a variety of features including navigating among Web pages. searching the Web using a selection of search tools, accessing and managing Favourites, viewing a History of visited pages, printing, and accessing email and newsgroups.
• Address Bar: This is not really a toolbar, but this is where you type in the URL. (Web address) of the page. When you press the Enter key. it will take you to this address.
• Home: The home icon takes you back to the page that was on the screen when you first started IE, You can customize your seletion.
• Search: The search button opens up a function that uses one or more Web search tools. You can choose the search tool(s) you want as default.
• History: The history function allows you to view and select Web pages you have recently visited. You can sort your items by clicking on the black triangle to the right of the word View. You can sort by size, date the number of times visited, and the order you have visited today.
• Mail: you can read email from this window. Choose the email software you wish to use by going back to the Menu Bar and choosing Tools/ Internet Options/ Programs.

Toolbal Options for the Menu Bar

The menu bar at the top of the screen includes some useful options. Here are a few highlights.

• File/ New/ Window: You can open up a second copy of IE by using this feature. This allows you to visit more than one Web page at a time.
• File/ Edit with ......: You can edit the current Web page using the editor of your choice. Select the editor by going back to the Menu bar and choosing Tools/ Internet Options/ Programs. Your choices will be determined by software installed on your computer.
• Edit/ Find (on This Page): IE allows you to do a text search of the document on your screen. Choose this option and type in the word or phrase you wish to search.
• Tools/ Show Related Links: IE will display pages that are related in context to the current page. This is a Web content and traffic analysis company. The Tools menu offers you many ways to customize IE.