Know your computer

Know Your ComputerKnow Your Computer

Presentation developed by

Linear Linux(Jayant Ityalam)

AgendaAgenda

• IT and the information processing cycle

• What are computers?

• Kinds of computers – mainframes, minicomputers, and microcomputers or personal computers

• Components of a computer – hardware, software

• Hardware – CPU, storage devices, input devices, display and output devices

• Software – Operating system and programs

• Applications – Word processing, desktop publishing, spreadsheets, databases, network, and multimedia

Agenda….contd.Agenda….contd.

What Can IT do?What Can IT do?

• The tasks that are being handled through IT are increasing day by day.

• IT can do at least three things:– Process raw data into useful information– Recycle processed information and reuse it

for other purposes– Package information in a new form that is

easier to understand.

Information processing cycleInformation processing cycle

• Information processing is a small step in the larger cycle: input, processing, output, storage and retrieval, and distribution and communication.

• The computer is at the very heart of Information technology. Computer hardware and software are used in every one of these steps.

What are ComputersWhat are Computers• Computers are electronic devices that

are capable of processing data/information given in the form of numbers, words, pictures, and even sounds.

• They can be programmed (given instructions) to carry out various kinds of information processing jobs.

What are Computers …What are Computers …

• Various kinds of jobs that are done using computers:– Scientific computations– Keeping track of information -- Banking, Railways

or Airlines Reservations – Preparation of documents and multimedia

presentations– Simulation of real or imaginary world scenes –

Virtual Reality, Computer Games– Storing and sharing information – World Wide

Web

Different Kinds of ComputersDifferent Kinds of Computers

• Depending on the size and capacity, computers are classified into three types: – Mainframe computers– Minicomputers– Microcomputers or Personal computers.

Mainframe ComputersMainframe Computers• Large and powerful computers that are used by

many people (users) at the same time; typically installed in large organizations.

• Located in a central place and accessed by users via computer terminals or other computers placed at different locations and connected to the mainframe computer.

• Supercomputers: Extremely powerful mainframe computers used in scientific and engineering applications.

MinicomputersMinicomputers

• Minicomputers are medium sized computers -- Between Mainframe computers and Microcomputers

• Are also used by many users at the same time

• Used in small organizations.

What is a SERVER?What is a SERVER?• Until recently, the big computers were called as

mainframes and the smaller ones as minicomputers.

• As computer networks have begun to dominate, the mainframe has just become one of many computers. However, because of its large size, it is often the one where other computers on the network look for data and also the one that runs powerful software and serves other computers.

• Hence the term Server.

Microcomputers or Personal Microcomputers or Personal ComputersComputers

• Small computers that fit on your desk; meant to be used by one user (at a time)

• Workstation: A microcomputer with enhanced graphics and communication capabilities

• Laptop: A microcomputer that is small enough to fit in a briefcase.

• Network computer: A small microcomputer with no built-in disk storage, but makes use of larger computers of the company’s network or the Internet through a browser

Microcomputers …Microcomputers …

• With the advent of smaller and faster computer chips and low-cost-high-capacity storage devices, present day personal computers are becoming more and more powerful, with capabilities comparable to the mainframe computers of olden days.

Components of a ComputerComponents of a Computer

• The components of a computer are classified into the two main categories – hardware and software

• Hardware: The mechanical and electronic parts that perform the various tasks of the computer

• Software: The programs that tell the hardware what tasks are to be done and how.

Hardware componentsHardware components

• The hardware of a typical computer system, irrespective of its size, consists of the following components:– Central Processing Unit -- CPU– Memory and Storage devices– Input devices– Display and output devices.

Central Processing Unit (CPU)Central Processing Unit (CPU)

• The CPU performs arithmetic and logical calculations and controls the operations of other parts of the computer.

• The CPU may be a single silicon chip or a series of chips. A chip contains thousands of electronic switching circuits.

• Each circuit can be set ON or OFF and it represents a bit whose value can be 1 or 0.

• Computer stores and processes data/information in terms of these bits.

Computer speedComputer speed

• A basic arithmetic operation like addition of two numbers is a single computer instruction. An instruction is executed in one or more clock cycles.

• Computer speeds are measured in megahertz or millions of clock cycles per second.

• Typical speeds of present day microprocessors are few hundred megahertz.

• A super computer can do trillions of arithmetic and logical operations per second.

Data representation and sizeData representation and size• Typical representation of various data:

– A character is represented by one byte– An integer is represented by 4 bytes.– A floating point is represented by 4 or 8 bytes.– The size of data to represent a color picture (image)

covering one fourth of your computer screen may be a few MB.

• 1 byte = 8 bits• 1 KB (kilobytes) = 210 that is about one thousand bytes• 1 MB (megabytes) = 210 KB• 1 GB (gigabytes) = 210 MB.

Memory and Storage DevicesMemory and Storage Devices• Computer Memory, also known as internal storage device,

consists of silicon chips that are directly linked to the CPU.• There are two kinds of memory

– Read-Only Memory or ROM: Contains basic instructions of the computer stored permanently

– Random-Access Memory or RAM: In RAM the computer copies and keeps temporarily user’s programs and data, in part or full, at the time of execution.

• The size of RAM is important for speedy execution of large programs. For a personal computer, typical size of RAM is 32 or 64 or 128 MB.

Memory and Storage Devices …Memory and Storage Devices …

• In order to store user programs and data permanently or as long as user wants, computers use (external) storage devices.

• The common storage devices used in personal computers are:– Hard disks: These are disks, fixed inside

the cabinet, used for storing (read and write) very large amounts of information. Typical sizes are about 4 or 8 GB.

Storage Devices …..Storage Devices …..

– Floppy disks: Used by means of floppy disk drive(s) attached to the computer. Floppy disks in normal use today store about 800 KB or 1.4 MB of data – read and write.

– CD-ROMs: Used by means of CD-ROM drive(s). Standard capacity is about 600 MB of data – read only.

• While a hard disc is fixed to the computer, floppy disks and CD-ROMs are removable and can be used to transfer data.

Input DevicesInput Devices

• Input devices are used by the user to enter data, commands and programs to the computer. Most common devices are:– Keyboard: Used to enter text data.– Mouse: Used to point and click at any

location on the computer’s video display screen. Normally a mouse will have two or three buttons.

– Trackball: Replaces the mouse on laptops.

Input devices …Input devices …

• Other input devices– Joystick: Similar functionality as mouse – Light pen: Used to point or sketch directly

on the screen.– Scanners: To scan (input) images– Digital cameras: To capture pictures

directly.– Voice recognition systems: These accept

spoken words as input.

Display and Output DevicesDisplay and Output Devices• Monitor or Display: It is the main output device of a

computer. It displays text as well as pictures in black and white or color.– The monitor screen consists of an array of tiny dots

called pixels (picture elements). Typical sizes of this array of pixels are 640 by 480 or 800 by 600 or 1024 by 768. This is also referred as the resolution.

– Each pixel can be independently illuminated by a color. The number of colors displayable on a monitor can be 16 or 256 or 216 (high color) or 224 (true color).

– Resolution and number of colors can be set by user.

Output Devices …Output Devices …

• Printer: Another output device to which the computer can directly send the data to obtain hard copy printouts of the results. – Laser printer: Commonly used printer. In

general it will be black and white. There are also color laser printers.

– Other types of printers: Ink-jet printer, Dot-matrix printer.

ModemModem

• A device used to link two computers via (analogue) telephone lines.

• It converts digital signals into analogue signals and vice-versa.

Computer SoftwareComputer Software

• Computer software can be classified into following categories:– Operating system– User Programs– Application programs

Computer Hardware

Operating System

Application Programs

User Programs

User

Operating SystemOperating System• Operating system (OS) is the basic software

responsible for interacting with the hardware.• It is the foundation on which user programs and

application programs are built.• It helps the user to enter programs or data, store

them in files and execute programs. • Two popular operating systems in use today are

– Unix – for mainframes and minicomputers.– Microsoft Windows – for personal computers.

ProgramsPrograms• A program is a sequence of commands written

in a computer programming language that specifies a task the computer will perform.

• Some of the computer programming languages are:– FORTRAN, COBOL, BASIC, C, C++, Java

• User Programs: Written by users or programmers for themselves or for their organization.

Application ProgramsApplication Programs• Computers are increasingly being used in

almost every activity - business, industry, commerce, health, education, entertainment, sports, etc.

• Application programs is the catch-all name for all programs that are used for carrying out specific tasks - office document creation, pay roll processing, …

• We discuss a few of the highly popular application programs

Word processingWord processing

• A word processor is an application program that supports the basic tasks of entering, editing, formatting and archiving a text document.

• Microsoft Word includes a number of powerful features, such as word wrap, find and replace, tables, columns, spell check, grammar and style analysis and mail merge.

Desktop PublishingDesktop Publishing

• Provides functions that until ten years back were only possible to be carried out at a good printing house.

• A basic function is page layout, the ability to place text, diagrams and images on a page in any way, easily and accurately.

• Other functions include a variety of fonts, styles, content and index generation, etc.

SpreadsheetsSpreadsheets

• A spreadsheet application program is used to enter numeric data in tabular format, along with row/column labels and formulae that can be combined to solve a variety of business numeric problems.

• Spreadsheet applications also include facilities for drawing charts, graphs, etc. from tabulated data.

DatabasesDatabases

• Database application programs are used when very large amounts of data are to be stored in a structured manner, maintaining various relationships among the data - for example, information of all employees in a company.

• A very powerful feature is the ability to rapidly answer a variety of queries from the user about the data in the database.

NetworkNetwork

• Network applications are programs that enable us to communicate with and use facilities of remote computers.

• These applications have proliferated with the spread of the Internet and the introduction of the WWW.

• Commonly used programs are - E-Mail, Newsgroups, Chat, Games, File transfer,...

MultimediaMultimedia

• It all began with games, now it is dynamic web pages, interactive courseware and catalogues with sound and video - multimedia application programs enable us to create exciting content.

• These programs include facilities to create, edit and render on the screen, text, pictures, sound, animation, video and 3D graphics

Further ReadingFurther Reading

1. R. Carter, The Information Technology Handbook, Heinemann Professional Publishing Ltd, London, 1987.

2. P. Scharf and J. C. McNichols, Understanding the Computer Age, Hayden Book Company, New Jersey, 1994.

3. Microsoft Encarta Encyclopedia 2000 CD- ROM, India Edition, 2000.