Ccp-unit 1 Chapter11

UNIT-ONE CHAPTER 1-INTRODUCTION TO COMPUTER CONCEPTS

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UNIT-ONE

INTRODUCTION TO COMPUTER SYSTEMS, INTERACTING WITH THE

COMPUTER, COMPUTER ORGANIZATION AND PROCESSING OF DATA .

CHAPTER_ONE: INTRODUCTION TO COMPUTER SYSTEMS

1.1 Definition of computer:

The word computer is derived from the word COMPUTE.

A Computer is an electronic device, which takes input from the user in the form of data

(i.e. text, numerals, audio, video and image) and instructions.

Once the computer receives the data, it waits for the user‟s instruction to process the data.

On receiving the instructions from the user, the computer processes the data and generates

some output and displays it to the user.

A Computer can perform the following tasks,

INPUT: Data and command which is sent to the computer is known as input.

PROCESSING: Work done by the computer with the help of processing hardware and

software to produce results is known as processing.

OUTPUT: The result displayed by the computer is known as output.

STORAGE: The result which is stored in a place inside or outside the computer is known

as storage.

1.2 Features of Computer:

The common features of the Computer are as follows,

Speed: The speed of the computer can be determined to process all computations in fractions of

seconds, it actually process large amount of information in seconds and displays the output.

Storage and Reliability: The storage capacity of the computer, i.e. how much amount of

information can be stored in the computer easily.

Accuracy: The accuracy of the computer is providing accurate results of the computation

performed by it, it actually does not commit mistake until input data has some error.

Versatility: Where the computer can be used such as in the field of teaching, training,

entertainment, accounting and hospitality.

Diligence : For how many hours computer can work without getting tiered, it gives acceptable

output even after running for long time.


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1.3 Early days of computer

The seeds of modern computer were sown 3500 years ago, when a huge stone carved structure

spread in a circular pattern over the huge ground was used to perform astronomical calculations

by considering the position of sunrays. This stone carved structure is known as NEOLITHIC

COMPUTER and the mode of calculation is known as STONEHENGE calculation.

The computer has evolved from a simple calculating machine over the centuries in the following

ways,

ABACUS:

Abacus may be termed as a sort of ancient computer.

Abacus was generally used for numerical calculation and still it is widely used by

merchants in Asia and Africa continent.

Abacus is also very popular among children in many parts of the world, as it helps them

to learn basics of calculation, it comes in different forms, size, colours and constructions.

BLAISE PASCAL:

In 1642, French mathematician Blaise Pascal invented a machine, called as NUMERICAL

WHEEL CALCULATOR.

Numerical wheel calculator became popular as PASCALINE.

In 1673, German mathematician Gottfried Leibniz invented a MECHANICAL

CALCULATING MACHINE that multiplies, divides, adds and subtracts faster than

Pascaline.

CHARLES BABBAGE:

In 1821, an English mathematics professor Charles Babbage invented a machine known as

DIFFERENCE ENGINE to perform mathematical calculations.

In 1856, he developed another machine that could perform not only mathematical task but

also any type of calculation and named it as ANALYTICAL ENGINE.

He is also known as “FATHER OF COMPUTERS”.

ENIAC &EDVAC:

ENIAC: Electronic Numerical Integrator And Calculator was the first electronic computer.

Two American scientists, John Presper Eckert and John W. Mauchly, jointly developed

ENIAC on February 19, 1946.

The speed of ENIAC was very fast, it could perform 5000 additions or subtractions and 360

multiplications in just one second.

ENIAC was big in size as compared to today‟s computer, it was 80 feet long , weighed 30 tons

and consumed lot of electricity and it was very expensive.

It was used to calculate the trajectories of bombs and shells

It had short memory and its components need a manual reset of wiring for performing

different calculations.

John Von Neuman proposed a new concept of storing information in a large internal memory

that overcomes the disadvantages of ENIAC.

This concept is also known as stored program concept, based on this concept a new computer

came into the market and called Electronic Discrete Variable Automatic Computer-EDVAC.


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IBM Personal Computer:

In 1970s IBM –International Business Machine decided to provide computers to common

people.

In 1981, IBM developed a personal computer (PC).

A personal computer can be used anywhere and by anyone.

1.4 Five Generations of Modern Computer

First Generation of Computer (1941-1956)

First generation computers distinguish different versions of operating systems particularly

designed to complete a single task and concurrent tasks were not able to process.

It uses vacuum tubes and magnetic drums for the purpose of data storage.

Each computer contains a different binary coded program known as machine language that

helps the computer to operate, due to this computer performance limited its versatility and

speed.

Breakthrough in first generation of computers came when an engineer at IBM developed first

electronic computer.

In 1944, Howard H. Aiken at IBM came up with electronic computer.

The major contribution on the first generation computers was the invention of ENIAC.

In 1945, EDVAC developed by John Von Neuman and it contains memory to hold both the

stored program and data.

This stored memory and conditional control transfer techniques that provides versatility in

computer programming that allows the computer to be stopped during the process and then

resumed.

In 1951, UNIVAC I-Universal Automatic Computer developed by Remington Rand was and

this was recognized as the first commercially available computer.

Second Generation of Computer (1956-1963)

Vacuum tubes were replaced by transistors in second generation.

Due to use of transistors the computer were small, fast, and precise, in making calculations

and consumes less electricity.

It was comprised of printers, primary memory, storage media to save documents and retrieve

later on, and operating systems.

It was programmed with assembly language instead of machine language.

The various manufacturers of this generation computes were Burroughs, Control Data,

Honeywell, IBM, and Sperry-Rand.

The use of stored program and programming language transformed computers as flexible,

cost effective and productive for business use.

The stored program refers to instructions that run on a computer for a specific function or

program is stored inside the computer‟s memory, these instructions could quickly be replaced

by a different set of instructions to perform a different function.

COBOL –Common Business-Oriented language and FORTRAN-Formula Translator

languages came into use.


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Third Generation of Computer (1964-1971)

Though the transistors were better than vacuum tube, but they produce enough heat to damage

internal circuitry and other heat sensitive electronic devices of the computer.

To overcome the above mentioned problem Integrated Circuit(IC) was developed in 1958 by

Jack Kilby.

IC added together three electronic components on to a small silicon disc which was made

from quartz.

After sometimes scientists started to fit more components on a single chip such as

semiconductor, thus the size of computers started to decrease as more components were

squeezed onto the chip.

In this generation the usage of the operating system was developed much more, which

allowed machines to run different programs simultaneously with a central program, that

monitor programs and helps them to coordinate with the computer‟s memory.

Fourth Generation of Computer (1971-Present)

The size of the computers reduces enormously and thousands of components were squeezed

onto a single chip.

In 1971, Intel a major chip manufacturer came up with its own chip, known as 4004.

The 4004 chip of Intel was one step ahead than IC, as it brings central processing unit,

memory, input and output that control a single chip.

At present one microprocessor could be programmed to meet any number of requirements.

Computer starts coming with user friendly interface that offered the non technical users to run

applications such as word processing and spread sheet programs on the computer.

In 1981, IBM launched PC to use in homes, offices and schools.

Macintosh computer introduced an operating system to help users to move screen icons

instead of typing instructions.

The computers can be linked together or networked to share memory space software,

information and communicate with each other.

The computer networks such as the internet is the most famous for electronic mail (E-mail)

which allows user to send messages to a specified address through network terminals across

the domain or world.

Fifth Generation (Present and Beyond)

The major contribution of this generation computer is ARTIFICIAL INTELLIGENCE.

Many researchers are going on around the world to develop a SELF AWARE computer

which could be implanted in Robot to create a Replica of human being.

This generation computers are capable of recognizing speech, translate foreign language,

assist doctors in diagnosing the patients.


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1.5 Basic Parts of a Computer:

The basic parts of a computer are as follows:

1. CPU-Central Processing Unit

It consists of different smaller components such as Motherboard, Hard disk, RAM (Random

Access Memory), Floppy Disk Drive and Sound card.

CPU is usually is located in a tower shaped cabinet.

2. MONITOR

It is used to display the output of computer.

It is Television like equipment which can be monochrome (black & white), LCD (Liquid

Crystal Display), VGA (Video Graphics Array) or SVGA (Standard Video Graphic Array).

Monitors can be analogue or digital.

3. MOUSE

It‟s a component that fits inside a palm.

It contains buttons (2 or 3) that help to work on a computer conveniently.

4. KEY BOARD

It‟s a device that contains keys to feed information into the computer.

Keyboards are available in two models, i.e. the standard model with 83-84 keys and the

enhanced model that contains 104 or more keys.

In addition to the basic parts (components) mentioned above, there are some optional component

which is shown in the table below.

BASIC COMPONENTS OPTIONAL COMPONENTS

Processor Hard Disk RAM Display/Video CardKeyboard Drives: Hard Disk, FloppyMouse Monitor

Printer Scanner Modem DVD Drive Speakers Zip Disk and CD-ROM Drive


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1.6 Basic Structure of a Computer:

A Computer is an electronic device which performs the following tasks:

Sending and accepting the data and command. User needs the input device to

send and accept the data.

Saving the result in the memory. A memory device is required for storing

information.

Processing the information stored in the memory. CPU is required to process the

information stored in the memory.

Displaying the processed information as output. Computer displays the output on

the output device such as monitor or computer screen.

I. SYSTEM UNIT

System unit is the important part of the computer system and it resembles as a rectangular

box.

The system unit contains some buttons and disk drives at the front side and sockets of

different shapes and sizes at the back side .

All input and output devices are linked to the system unit through cables which are plugged

into the back side of the system unit.

The core devices such as Motherboard, CPU, BIOS (Basic Input Output System), RAM, Hard

Disk, Power Supply Box, are safely kept inside the system unit.

INPUT

DEVICE

CPU

OUTPUT DEVICE

Control

Unit

Arithmetic

Logic Unit

Memory


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Front side of the system unit:

The various components seen in the front part of the system unit are as follows:

1. Power Switch: Turn ON or OFF the power to the PC.

2. Reset Button: To restart the computer without disconnecting the power supply.

3. Lights : Indicates whether the Hard disk, Floppy Disk or CD-ROM is been read or written.

4. Floppy Disk Drive :

It is the component which enables to read or store information on floppy disks.

The system unit contains a slit in which the floppy disk can be inserted, motor to spin the disk

and recording or reading device that moves across the disk to read or write data.

5. DVD/CD Combo Drive :

Allows reading and saving the data on CD.

In DVD it allows only to read the data on DVD but not to save any data on DVD.

We need an enhanced version in Combo drive which includes the functionality to save data

on DVD.

Back side of the system unit:

The back side of the system unit contains the various connection points of different shapes which are

known as PORTS.

Different Types of Ports are,

1. Parallel Port: It connects the computer to the printer, it is also known as printer port.

2. Serial Port: It is a general purpose interface for almost any type of devices such as modems,

mouse and keyboard.

3. Universal Serial Bus (USB) Port:

It‟s a plug and play port of the computer with which we can attach devices such as Audio

players, Joysticks, Keyboards, Telephones, Scanners and Printers.

A single USB port can be used to connect up to 127 peripheral devices.

4. Power Socket:

Supplies the electricity to the computer.

A power cable is plugged in to the power socket which carries the power from the electrical

outlet to the system unit and from the system unit to the monitor.

5. Fan:

It works like an exhaust fan.

When computer is switched on and work is done continuously its machinery produces a lot of

heat. If this heat is not moved out from the system unit it causes havoc to the computer

machinery. The fan stops this from happening.

When the computer is switched on the fan starts rotating and throwing out the heat from the

system unit.

The fan keeps on rotating until the computer is switched off.


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Inside the system unit:

The various devices present inside the system unit are as follows,

1. Motherboard

A motherboard is a component that contains the computer‟s basic circuitry and other

components of the computer.

An electronic circuitry is printed or fixed on the surface of the motherboard and this task is

done at the time of manufacturing the motherboard.

A motherboard contains the connector for attaching additional boards i.e. the controllers for

all the standard devices such as display screen, keyboard and disk drive.

The chips that reside on the motherboard are known as mother board‟s chipset.

A motherboard is also called a Printed Circuit Board (PCB).

These days‟ motherboards have dual processor capability which means two processor can

work simultaneously.

2. CPU-Central Processing Unit

It is the Brain of the computer.

It looks like a small chip and is placed on the motherboard.

The power of CPU lies in its ability to process data rapidly and flawlessly.

The speed of CPU is measured in MHZ (Mega Hertz).

The processors such as Intel Pentium, Celeron and AMD.

Two typical components of CPU are

I. ALU (Arithmetic Logic Unit)-Performs arithmetic and logical operations.

II. CU (Control Unit)-Extracts instructions from memory, decodes and executes

instructions and takes help of ALU if required.

II. BIOS-Basic Input Output System

BIOS is built in software which keeps track of all devices attached to the computer and

provide intercommunication channel between devices such as keyboard, monitor and disk

drives.

Types of BIOS are,

1. Read Only BIOS- That could not be altered, this means that new components could not be

added to the computer because the BIOS would not know how to communicate with them.

2. Flash BIOS- When a new component is installed in a computer the flash BIOS can be

electronically upgraded so that it can recognize and communicate with the new devices.

3. ROM BIOS- BIOS is typically placed in a Read Only Memory (ROM) chip, this ensures that

BIOS will always be available and will not be damaged by disk failures.


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III. Memory

A computer stores data in units called Bits and Bytes.

Bits are grouped together in sets of 8 which is called a Byte.

i. 8 bits= 1 byte

ii. 1024 bytes = 1 kilobyte (KB)

iii. 1024 Kilobytes = 1 megabyte (MB)

iv. 1024 megabyte =1 gigabyte (GB)

The memory stands for data storage i.e. in the form of chips and the term storage is used for

memory that exists on tapes or disk.

RAM/ROM-Primary memory of computer

RAM-Random Access Memory

It stores instructions from operating system, application programs and data to be processed so

that they can be quickly accessed by the computers processor.

It is faster to read from and write to other kinds of storage, i.e. Hard disk, Floppy disk and CD

–ROM.

A more appropriate name for RAM is RWM (Read Write Memory).

Data stays in RAM only as long as computer is working, once the computer is turned off

RAM loses its data and hence it is called as volatile memory.

RAM chips are of different sizes such as 256 MB, 512 MB and 1 GB.

The types of RAM are,

1. Dynamic RAM (DRAM)

It‟s a temporary physical memory of the computer.

The term dynamic indicates that the memory must be constantly refreshed or it will lose its

contents.

It has more access time and is more volatile than SRAM.

2. Static RAM (SRAM)

It‟s a type of temporary memory.

It is faster and more reliable than DRAM.

It does not need to be refreshed like DRAM.

The access time is as low as 10 seconds.

Its cycle time is much shorter than that of DRAM, because it does not need to pause between

accesses.

3. Extended Data Out RAM (EDO RAM)

It is an improved version of DRAM.

It can perform more than one task at a time, when some data is sent to the processor another

chunk of data is retrieved from the RAM module.

This process enables the chips data to be accessed at very high speed.


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Read Only Memory (ROM)

It is a built in computer memory containing data that normally can only be read not written.

It contains the program that allows the computer to boot up or regenerate each time when

turned on.

The data stored in ROM is not lost even when the computer is turned off, there it is termed as

non volatile memory.

It is sustained by a small long life battery in the computer.

ROM‟s are extensively used in calculators and peripheral devices.

The types of ROM are,

1. Programmable Read Only Memory (PROM)

It represents a memory chip on which data can be written only once.

It retains its content when the computer is turned off.

PROM is manufactured as blank memory, where as ROM is programmed during the

manufacturing process.

A special device called PROM programmer or PROM burner to write data on to a PROM

Chip.

The process of programming PROM is called burning the ROM.

2. Erasable Programmable Read Only Memory (EPROM)

It‟s an erasable and reusable memory.

The data stored in EPROM is erased by an intense ultraviolet light passing through a window

that is designed in to the EPROM Chip.

3. Electrically Erasable Programmable Read Only Memory (EEPROM)

Content can be electronically erased and new information can be stored.

Secondary Memory of a Computer

Any internal or external storage device used by the user for storing data and programs is

known as secondary memory of a computer.

It cannot be directly accessed by the CPU.

It will not lose the data when the computer is turned off, so it is known as volatile memory.

1. Hard disk

It is the memory bank of the computer.

It is placed inside the system unit and connected to the mother board

The capacity of the hard disk is measured in Giga bytes and Tera bytes.

This is a magnetic storage device.

Magnetic storage devices are flat objects in a round shape, which spins around its centre, it

has read /write head which reads the data from the disk or writes the data to the disk.

It is a non removable storage device.

It uses electromagnetism to encode data.


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2. Floppy Disk

The floppy disk drive is an internal device mounted into an open drive bay of the system

keys.

This is the magnetic storage device and also a removable storage device.

The floppy disk is of different sizes such as 8 inch, 5.25 inch and 3.5 inch.

The 3.5 inch is the most popular disk from many years.

It uses electromagnetism to encode data.

3. CD/DVD

Compact Disk (CD) has very large storage capacity but they are not as fast as hard disk.

This is a removable storage device.

Optical disk systems such as CD/DVD use a laser beam to read and write data.

Inexpensive optical disk drives are Read only.

4. Blu-ray Disc

It is an optical disk storage media format.

It is used to store high resolution video and pictures and large volume of data.

This disk has the same dimension as standard DVD/CD.

The name of this disk is derived from the BLUE-VIOLET LASER used to read and write this

type of disk.

This disk can store more amounts of data as compared to DVD.

A dual layer Blu-ray disk can store 50 GB of data almost 6 times the capacity of dual layer

DVD.

This is the removable storage device.

5. USB Flash Drive (Data or Memory stick)

It is a type of flash memory data storage device integrated with a USB (Universal Serial Bus)

connector.

It is typically small, light weight, removable and re-writable.

USB drives use the USB mass storage standard, supported natively by modern Operating

System (OS) such as Windows, Linux, Mac OS X and UNIX like systems.

IV. Cards

All standard motherboards are built in support for hardware devices.

A card is printed circuit board that can be inserted into an expansion slot of motherboard

to give additional capabilities to the computer.

Expansion slots are long and narrow connectors which allow us to plug in cards.

Cards are also called expansion boats, adapters, add -ins or add- ons.


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The commonly used cards are

A). Display/Video/Graphic Card-Displays the data to the user.

It is indirectly linked with computer memory.

There are 2 types of display cards,

a. The PCI graphics card

b. The AGP card

B). Sound Card

The sound card converts the digital information into electrical signals that speakers use.

When the speaker is connected to the sound card, the sound can be heard on the speaker.

It allows to play sound and music.

C). Network Interface Card (NIC)

It allows connecting to the network.

Most NIC‟s are designed for particular type of network, some can serve multiple networks.

V. Switch Mode Power Supply (SMPS)

The power supply is the metal box usually found in a corner of the system unit.

The power supply box is visible from the back side of the system unit because it contains the

power cord receptacle and the cooling fan.

It is often referred as a switching power supply.

It uses switcher technology to convert the AC current to DC current.

When the current is converted into DC the power supply sends the required power to the

different components of the computer such as Monitor, Hard Disk, CD-ROM and Floppy

Disk Drive.

The measurement unit of voltage is Watts.

1.7 Categorizing Computers

Computers are of various shapes and sizes; it can be as small as your palm.

It can also occupy many rooms of building.

Earlier computers were categorized on the basis of principles of working and the categories

are

i. Analog Computers

ii. Digital Computers

iii. Hybrid Computers

Analog Computers Digital Computers Hybrid Computers

Process the analog datarepresented in a continuousrange.

Process the digital datarepresented in the binary form.

Process the digital data by usingthe analog solution of theequations.

Process the data bymeasuring

Process the data by counting. Uses combination of processingtechniques

Process mathematical andscientific data easily.

Process mathematical and scientific data by using complexlogics.

Process mathematical andscientific data easily.

Require less or no memory Require memory necessarily Require less amount of memory


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Besides shape and size computer also vary from each other in terms of speed to process the

data.

Based on the above mentioned factors such as shape size and speed, the computers are

categorized into two types,

i. Computer for Individuals

ii. Computer for Organization

i) Computer for individuals:-

A single user can work on a computer at one time, and then a computer is for individual user.

This computer includes

a). Desktop computer

This is small in size and primary used in office or home without the need to be connected to

the large computer.

It is also called Personal computer.

In early 1980‟s the first low cost fully assembled units were mass marketed with a typical

configuration consist of video display, keyboard, mouse, logic unit, memory, storage device

often modem.

PC‟s are generally in two shapes

1. Tower

2. Desktop

b). Handheld computer or Personal Digital Assistant (PDA)

PDA is a light weight handheld computer that is designed to use has a personal organizer with

communication capabilities.

PDA has no keyboard instead it relies on recognition of hand written input through the use

of stylus.

Stylus is a special type of pen used to write text and select option on the LCD screen.

It includes applications such as word processor, spread sheet, calendar and address book.

PDA „s are envisioned has notepads appointment schedulers and wireless communicators for

sending and receiving data , faxes and electronic mail messages.

c). Laptop computers

Laptops are portable computers that are integrated with display screen, keyboard track ball

processor and memory.

Entire machinery of laptop computer is rechargeable battery oriented

We can carry laptop computer anywhere and need not stick at one place to work on a

computer.

Laptops are expensive than personal computers and they are generally used by the users who

travel frequently.


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d). Tablet PC’s

It is a kind of micro computer which offers a host of new features to the IT world.

It is the venture of Microsoft in to the world of natural interfaces.

It involves new data transfer techniques such as hand writing recognition, voice command

and finger print authentication.

With its electromagnetic pen, touch screen and software, it recognises letters written on the

screen.

The pen can act as a mouse when moving over a tablet PC, when the pen touches the screen it

acts a ink pen and the user can write directly on the screen.

Tablet pc hope s to be the notepad of the 21st century.

e). Smart Phone’s

Smart phones are basically the mobile phones providing additional features required to

perform day to day task.

The additional features include sending mails and accessing the internet , built in camera and

music player

We can perform almost all the task with smart phone that can be performed using desktop

computer.

ii). Computers for Organization

When multiple users are required to work and perform multiple task we make use of

computers which are designed for the need of organizations

The computers used by organizations are as follows

a). Mainframe Computers

These are the large size computers which occupy a large air conditioned room full space and

main memory size up to 128 mega bytes.

All its peripherals are mounted in a large cabinet type of frames, hence these computers are

known as main frame computers.

128 users can use main frame computers simultaneously in the time sharing mode and

employing mini computers as a front end processor.

First to third generation computers which work with the speed of 5-100 million instructions

per second fall under this group.

IBMs 308x-580 series, IBM -3090, 4300, 4381, DEC1090, 10, 20, Cybers170, ICLs series 9,

Honeywells DPS 88/860, Burrough 7800, UNIVAC 1100/60, ACOS100 are examples of

popular mainframe computers.

A mainframe computer is associated with centralized rather than distributed computing.

b). Super computers

Super computer means a computer having main memory of 256 mega bytes, working on

vector architecture with 64 bit words and performance peak time in range of 500 million flops

o (Floating Point Operations per Second) where ENIAC and Colossus were in the

region of 100 flops only.

Super computers speed of processing has helped in the development of 3 very important

concepts in computer architecture


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o Pipelining

o Vector processing and

o Parallel processing

Super computers are the largest, fastest and most extensive computers.

The processing speed of data exceeds 400,000,000 – 600,000,000 operations per second.

Cray-2 is an example for super computers which operates at a speed of 1.2 billion flops,

and can perform calculations in one minute which a personal computer could perform in 3

weeks.

c). Self destructing computer

When a computer is stolen from the computer thieves, they can retrieve data from the stolen

computer.

In order to limit the amount of data that can be retrieved from the computer thieves a device is

being developed that can locate and if necessary destroy a computer hard drive.

Cyber group network corp. (CGN) developed the first self destructing computer and the name

of the device is C-4 chip.

If a computer equipped with C-4 chip is discovered missing or stolen the computers owner

will be able to call a toll free number that will be available 24 /7 in more than 20 countries.

This phone service will give the owner 4 options

o Track the computer

o Track the computer and retrieve the data from the hard drive

o Track the computer and destroy the hard drive and mother board

o Notify the authorities

According the manufacturers of the device a computer embedded with C-4 chip can guarantee

99.9% that al information stored on your hard drive is secured.

The manufacturers intend to expand the devices capability so that it can be used with PDAs

and other electronic devices.

The company also plans to form alliances with several computer manufacturers such as apple,

Compaq and dell with the goal of installing the device in those company products.

1.7 Information processing Life Cycle

Consider an example of mixer which is used in daily life. It is a food processing device.

If Cold coffee is to be prepared, then merely collecting the ingredients used in cold coffee

(Milk, coffee, sugar and ice) does not mean that cold coffee is prepared.

Until and unless the ingredients are mixed in mixer, the cold coffee is not prepared.

For preparing the cold coffee, all ingredients should be put in jar and press mixer‟s button.

Mixer starts mixing the cold coffee ingredients and once it is done the mixer is turned off.

Then it can be either served or stored in some cold storage such as thermo flask for later use.

Now, relate mixer in context of preparing cold coffee with data processing by computer.

Comparison between a Mixer and a computer is shown in the below table.


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Mixer Computer

Ingredients of cold coffee

The mixer

Ingredients put in the jar

Button pressed by the user

Mixer starts mixing ingredients

Button pressed by the user to stop mixing

A glass of cold coffee

Thermo-flask

Putting coffee in thermo-flask

Bring coffee out of thermo-flask

Data

Computer system

Data input to the computer

Instruction to start processing the data

Data is being processed

Instruction to display result

Output/ Information

Memory device

Saving the output/ Information in memory

Retrieving the output/ information from the

memory

Therefore, from the preceding analogy, it can be concluded that computer has the following

basic operations:

o Similar to a mixer that can start and stop mixing on pressing its buttons; a computer

system has devices, which the user uses to input or feed data and instructions to the

computer. Such devices are known as Input devices. Some commonly used input

devices are keyboard, mouse, track ball and scanner.

o Like mixer, computer also has machinery to process the data input by the user. Such

machinery is called the system unit of the computer. System unit consists of several

parts that work together to produce the results.

o As anything being prepared in the mixer can be seen, computer also has device to

display the output to the user. Such devices are known as Output devices like monitor

and printer.

o A thermo-flask is used for keeping the cold coffee; computer also provides some way

or devices to save the output for later use. Commonly used storage devices are

floppy, hard disk, CD-ROM and magnetic tape.

1.8 Essential Computer Hardware

Any computer or device that we can see and feel is known as hardware.

The two categories of Hardware devices are,

A). Input devices

Any device which lets to enter the data or instructions is known as input device.

Examples of input devices are as follows

a.) Keyboard


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A keyboard looks like a typewriter.

Numeric keypad is located to right of the keyboard.

The keyboard is also known as QWERTY keyboard.

It is also called as the universal keyboard.

The Christopher Sholes, the inventor of the typewriter designed the arrangement of

characters on a QWERY keyboard in 1868.

Keyboards are available in 2 models

1.) Standard model- with 83-84 keys

2.) Enhanced model- 104 or more keys.

Various keys present on the keyboard is as follows,

1.) Typewriter keys- include letters, numbers and punctuation symbols and these keys are used

for typing and designing.

2.) Function keys- The keys are labelled from F1-F12 located at the top end of the keyboard, the

functions they perform depend on the software that we use.

3.) Cursor Control keys- Appears as left, right, up and down arrow keys and these keys enable us

to move cursor to the left, right, up or down the screen one line or one character at a time.

4.) Numeric keys-

It is just below the function keys along with some special characters printed on the

top side.

The right hand side of the keyboard contains the numeric keypad, comprising

calculator like keys and these keys have double functions.

The switch over between the two functions of numeric keypad is controlled by the

key marked unlock.

5.) Page up and Page down keys- It allows to move to preceding and next pages of the document

respectively

6.) Home and End keys- It allows to move the cursor to the top and end of the document, line or

window respectively.

7.) Caps lock key- Once we press the Caps lock key. it allows to type text in uppercase and once

again if we press the Caps lock key it allows to type in the lower case.

8.) Shift key-

It allows to type text in uppercase by holding the shift key and then pressing letter key

creates an uppercase letter, if the caps lock is on then this effect is reversed.

When there are two symbols or characters on a key using the shift key causes the upper

symbol to appear example- !,@,#.$ and so on.

9.) Control and Alt keys- Allows carrying special actions such as by pressing control- alt- delete

keys simultaneously the machine automatically restarts.

10.) Enter key- Allows to start processing the data, when the Enter key is used in the MS-word it

will lead to the starting of the next line and it is also referred as return key.

11.) Tab key- It moves the cursor along a line to a preset point and it is also used to move from

one option to another in a Menu.


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12.) Esc(Escape) key- It allows to cancel or ignore the entry or command that have been just

entered in an application.

13.) Delete and Backspace keys- Delete key erases a space or a character that is placed to the

right side of the blinking cursor and the Backspace key erases the character to the left side of

the blinking cursor and it moves the cursor back one character at a time and erases the letter

which was typed last.

b.) Mouse

Mouse is a hand held device that allows to control the computer without

typing the instructions from the keyboard.

User places the palm over the mouse moves it across a mouse pad and as a

result pointer moves on the screen.

Using the mouse we can select icons, open programs and select commands

present in a program by moving the mouse pointer.

Mouse has a primary button-left button, it is used to carry out most of the

task.

As a secondary button-Right button, it is used in special cases such as

opening short cut menus.

The selection of icons and commands by positioning the tip of the arrow over

the desired choice and clicking the mouse button.

A small wheel between the mouse buttons is used to scroll documents and

webpage‟s backward-scroll down or forward-scroll up.

Wireless mouse means that the mouse is not connected to the computer, it

relies on the infrared or radio waves to communicate with the computer.

It is more expensive than normal mouse.

c.) Scanner

Scanner is a device that can transfer typed or hand written text, graphs, diagrams

and photographs to the computer.

Instead of making a duplicate copy on a paper of the required data or photograph

scanners stores them in the memory of the computer.

Two types of scanners are as follows

i.) Desktop scanner-Scans single sheet of paper and pages of a book and it is very

expensive and less compact.

ii.) Handheld scanner- Helps to manually move the image that we want to scan and it is

inexpensive and portable.

B). Output Devices

The device which displays results is known as output device.

Examples of output devices are ,

a.) Monitor

Monitor of a PC works like television screen.

It displays text, characters and graphics in colours or shades of grey.

It is also known as screen, display or CRT (Cathode Ray Tube).

An image is made up of tiny dots called Pixels.


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Anything typed from the keyboard is displayed on the monitor and when the program is

executed the information is displayed on the monitor.

The result on the screen is shown temporarily and is not permanent unless they are saved in

the hard disk.

Various types of monitors are,

a. Monochrome- Single colour

b. Colour monitor

Monitors differ in terms of their resolution.

Resolution means sharpness of the image on the screen.

Higher the resolution more expensive is the monitor.

Colour monitors have higher resolution.

High resolution monitors are used for special jobs such as creating graphics and images.

b.) Printer

A device that prints images, numbers, alphabets and graphs on a sheet of paper is known as

printer.

After creating a document on a computer it can be sent to the printer for printing its hard copy

and the hard copy printed from the printer is called as printout.

The speed of printer is rated either by pages per minute (ppm) or characters per second

(cps).

Printout can be in full colours or in black colour.

c.) Speakers

Computer has a set of two speakers.

Speakers have a built in amplifier and is magnetically shielded so that it does not interfere with the

picture quality of the monitor.

Other Hardware devices

Modem

It is known as the modulator or the de modulator.

It is an electronic device which helps transmit programs and data locally or around the world

through the telephone line.

The main function of modem is to transform digital signals into the analogue signals and vice

versa.

The two modes of connecting modems are,

i. A modem may be card mounted inside the PC called as internal modem

ii. A modem can be a separate piece of equipment that connects to the serial port of the PC

through a cable is called as external modem.

Any mode of the modem is then connected through the telephone lines and the data is

downloaded from the internet.


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It incorporates a diverse range of features such as e-mail, banking, travelling and reservations.

Web Camera

A web camera is a video camera attached directly to the computer.

A live camera is a camera that continuously provides new images which are transmitted in

rapid succession.

Cameras are easy to connect through a USB port.

Web cameras are mainly used for Video chatting, Video conference etc.

Fax

Fax is the transmission of scanned in printed material through a telephone number associated

with the printer for other device.

The original document is scanned in the fax machine which treats the content as a single fixed

graphic image and converts it into 0‟s and 1‟s.

The information is transmitted as the electrical signals through the telephone system.

The receiving fax machine re-converts the coded image and prints the paper copy of the

document.

The components of a fax machine are as follows,

1.) Optical Scanner- Converts the outgoing page into the digital format, then the scanned

document is handled to the modem for transmitting through the phone line.

2.) Paper supply Tray- Allows to keep papers in supply bin and is fed to the printer.

3.) Control Panel- It contains the number of buttons to control the working of fax machine and it

displays the incoming phone number and the number of pages sent or received.

4.) Paper Feed Tray- Stores outgoing documents, the paper feed mechanism passes each page of

the document to the optical scanner.

5.) Modem- Converts the electronic information into a signal that can be transmitted over the

telephone wires.

6.) Printer- prints incoming faxes, it uses ink jet printing technology to give a high quality print.

7.) Head phone and Mike- Head phones are used to listen music without disturbing others and it

head phones come with built in mike which can be used for voice based chatting and making

phone calls over the internet and we can hear the voice and speak to our friends

simultaneously by using head phone.

1.9 Essential Computer Software

Software is the set of programs necessary to carry out operations for a specified job.

Programs are step by step instructions that tell the computer how to carry out operations for specific

job.

The two types of software‟s are,

1.) System Software

System software consists of programs, languages, and documentation supplied by the

manufacturer of the computer.

System software is required to use the computer efficiently and conveniently.

It allows the application developer to write and develop their own programs.


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Examples of system software are Operating systems (Windows 2000, Windows XP, Windows

Vista), Drivers (Sound card driver, Display Driver).

2.) Application Software

It is not possible to imagine this modern world without computers.

There are different types of programs for managing different types of information and they

are as follows,

i.) Word Processing Program

It allows PC to work like a typewriter.

It allows typing a letter or report, and change words or move blocks of text around easily.

Word processing programs also count words and even check spellings.

Examples of word processing programs are Microsoft Word and WordPad.

ii.) Spreadsheet Program

Allows us to do a lot of calculation or financial planning.

A spreadsheet is made up of cells arranged in a grid.

Each cell contains a numeral value stored in rows and columns as a graph or chart.

iii.) Database program

Allows us to store, sort and retrieve large amount of data.

Invoices or orders which may be in large numbers can be managed better by using a

database.

Database software allows adding new information, search information through previously

stored data and print records.

Most widely used database program is Microsoft Access 2007.

iv.) Presentation Program

Enables us to represent information in a number of attractive formats.

These programs are useful for people who have to prepare reports and presentations very

frequently.

The most commonly used presentation program is Microsoft PowerPoint 2007

v.) Browser

Allows us to view web pages.

The two most popular web browsers are Netscape Navigator and Microsoft Internet

Explorer.

Both of the above mentioned popular web browsers are graphical browsers, which mean

that they can display graphics as well as text.

Most modern browsers can even present multimedia information, such as sound and

video though they require some kind of plug-ins for some formats.

vi.) Personal Information Manager

It helps to organize information and PIM enables to enter various kinds of textual notes

such as reminders, lists, and dates, and to link these notes together in useful ways.

PIMs such as Outlook also include calendar, scheduling and calculator programs.


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We can easily organize our contacts, phone numbers, and set reminders for a meeting or

task using Outlook 2007.

vii.) Multimedia Software

Allows creating and modifying animation.

Using these programs we can create 3D objects, move objects on a definite or random path,

and animate objects in a number of ways.

Examples of the multimedia programs are Flash, Director, Maya, and Sound Forge.

Documents

Ccp-unit 1 Chapter11