HARDWARE & SOFTWARE

Chapter 2

COMPONENTS OF COMPUTER SYSTEM The hardware and software is used as

unit to process data is called computer system.Hardware

Input Devices CPU Output Devices Storage

Software A set of instructions given to computer to solve a

problem is called software. Software is also called program Computer works according to the instructions

written in software

COMPONENTS OF COMPUTER HARDWARE Input devices

The data or instruction given to the computer is called input.

A hardware component used to enter data and instruction into computer is called input device

Output DevicesThe data processed into useful information

is called output.A hardware component used to display

information to the user is called output devices.

COMPONENTS OF COMPUTER HARDWARE CONTD… System Unit

System unit is a box that contains different electronics components of a computer system.

The electronics components in the system unit are connected to the motherboard.

Important components of system unit are CPU and memory

StorageThe hardware components used to store

data, instruction and information permanently are called storage devices.

Examples: Hard Disk, floppy Disk, CD, DVD, etc

INPUT DEVICES The data or instruction given to the computer is

called input. A hardware component used to enter data and

instruction into computer is called input device Types of input Devices

Keyboard Mouse Trackball Touchpad/Track pad Pointing Stick Graphic Tablet Touch Screen Digital Scanner Digital Camera Joystick

KEYBOARD

MOUSE

TRACKPAD/TOUCHPAD

TRACK BALL

POINTING STICK

GRAPHIC TABLETS

TOUCH SCREEN

DIGITAL CAMERA

SCANNER

JOYSTICK

MICROPHONE

OUTPUT DEVICES Hardware components that are used to

receive information from the computer are called output devices.

Output devices take information from the computer and convert it in a form that is understandable by users.PrintersPlotterDisplay devicesSpeaker& HeadsetsData Projectors

PRINTERS Printer is an output device that prints

characters, symbols and graphics on paper.

Printed output is called hardcopy. There are two types of printers.

Impact Printers Dot Matrix Printers Daisy wheel printers Line Printers

Non-Printers Laser Printer Inkjet Printer

IMPACT PRINTER Impact printer works like a typewriter. Prints characters or images by striking

print hammer or set of pins against an inked ribbon.

Ink is pressed from ribbon on the paper to produce the output.

Impact printers are used where low-cost printing is required.

DOT MATRIX Produces printed images when tiny pins

on a print head strike an inked ribbon. When ribbon presses against the paper

it creates dot that form characters and graphics.

Contains 9 to 24 pins. Higher number of pins creates more

dots that produce high quality image. Speed of most dot-matrix printer ranges

from 350 to 1100 characters per second.

DOT MATRIX PRINTER

DAISY WHEEL PRINTER It uses a print wheel. Print wheel is

called daisy wheel. Each petal of daisy wheel contains

characters A motor rotates the wheel. A hammer strikes a petal against the

ribbon when the desired character reaches the position on the paper.

This prints the character on the paper. Slower than dot matrix printer but

better in quality

DAISY WHEEL PRINTER

LINE PRINTER Line printer is a fast impact printer. It can print multiple characters on the

same line at a time. Its speed is measured in line per minute. Speed range of line printer is from

300LPM to 2400LPM Faster than dot matrix and daisy wheel. More noisy and provide limited font

capability. Example:Band printer and chain printer

LINE PRINTER

NON-IMPACT PRINTERS A non impact printer prints characters

and graphics on paper without striking paper.

The characters are printed on paper with some mean such as laser

Some printers use spray in while other use heat and pressure to create images.

These printers are faster than impact printer.

More costly than impact printers. Produce no noise during printing Print quality is better than impact

printers

LASER PRINTER Light Amplification by stimulated

emission of radiation. Similar to a photocopying machine. Uses laser beams to burn special powder

on page to create a permanent image. Prints a complete page at a time Typical laser printer provides a resolution

0f 1200 DPI or more. Produces very high quality prints. Printing speed of laser printer ranges

from 12 to 45 ppm

LASER PRINTER

INKJET PRINTER It prints characters and graphics by

spraying tiny drops of liquid ink on paper.

These printers can produce quality text and graphics in both black and white and color.

Typical inkjet printer provides resolution of 600DPI or more.

Slower than laser printer. Printers can print from 10 to 35 ppm. Inexpensive than laser printer

INK JET PRINTER

PLOTTER Plotter is an output devices that is used

to produce image quality graphics in variety of colors.

Plotters are used to create maps, architectural drawings, graphs and charts.

A plotter works by drawing lines on paper using pens held in a mechanical arm.

PLOTTER

MONITOR Monitor is most common output device. The output displayed by monitor is called

soft copy. Looks like a television and displays text and

graphics. Different display screen can be distinguished

on the following features. Size Color Resolution Refresh rate Dot Pitch Display Adapter

CRT MONITORS Cathode Ray Tube It can display text and graphics It used CRT that creates an image by an

electronic beam. CRT consists of one or more guns that fire a

beam of electrons inside the screen. The screen is coated with very tiny

phosphor dots from inside. The beam of electrons repeatedly falls on

the surface of screen. CRT in color monitor consists of three guns

RGB

CRT MONITOR

FLAT PANEL MONITORS Laptop PCs use flat panel monitors These monitor take less space. Flat panel monitor use a variety of

technologies Common technology is Liquid Crystal

display LCD monitor use much less power than

CRT. These are available in different sizes

such as 15, 17, 19, 21, 32 and so on.

FLAT PANEL MONITOR

SPEAKER & HEADSET A type of output produced in the form of

sound, voice or music is known as audio output.

Speakers and headsets are two commonly used audio outputs.

Many personal computers have internal speaker.

Headsets are also used to produce audio output

CENTRAL PROCESSING UNIT CPU is the brain of Computer It is the most important component of a

computer It is also called processor A computer cannot work without CPU CPU is located of Mother Board Performs operations on data according to

the given instructions It can performs arithmetic and logical

operations It executes and controls the computer

hardware

PARTS OF CPU ALU(Arithmetic and Logic unit)

Performs basic arithmetic functions such as addition subtraction multiplication and division

Logic unit perform logical operations like comparing two data items to find which is greater

CU(Control Unit) It generates signal to direct the entire computer

system It controls and coordinates all activities of

computer system. It does not executes program instructions Control unit communicates with arithmetic and

logical unit and other parts

REGISTERS A small high speed memory inside CPU CPU contains number of registers Registers are used to store information

being processed. Temporary storage area of instruction or

data Temporary results during processing are

also stored in registers Each registers has a predefined function

MEMORY Data in digital computers is represented

as a collection of bits. The smallest unit of data that can be

used by computer is called bit. A set of 8bit is called byte. One byte is required to store one

character.

TYPES OF MEMORY Different types of memories are random access

memory and read-only memory

RAM(Random Access Memory) It is also called Main Memory or Direct Access Memory Each individual byte in the entire memory is directly

accessible. Program must be loaded into RAM before execution RAM is Volatile

ROM(Read Only Memory) Instructions in ROM prepare the computer for use. Contents of ROM can only be read but cannot be

changed or deleted. It stores data and instructions permanently ROM is NON-Volatile

TYPES OF RAM DRAM

Dynamic Random Access Memory It is a type of memory that is used in most

computers Least Expensive kind of memory. It requires an electric current to maintain its

electrical state. Electrical charge of DRAM decreases with

time that may result in loss of data. DRAM is recharged or refreshed again and

again to maintain data. Processor cannot access data of DRAM when

its being refreshed.

SRAM Static Random Access Memory It can store its value without any need

to refresh the data. Expensive type of memory CPU does not wait to access data so it is

faster. It utilizes more power than DRAM It is normally used to built faster cache

memory.

ROM(READ ONLY MEMORY) PROM

Programmable Read-only Memory This form of ROM is initially blank Manufacturer can write data on it using special device The user can write data and instruction only once If there is an error chip becomes unusable

EPROM Erasable Programmable Read Only Memory Program and data written on it can be erased using

ultraviolet rays. EEPROM

Electronically erasable Programmable ROM User can erase and write instruction using electrical

devices Contents can be modified easily

MEMORY Cache Memory

Designed to speed up the transfer of data and instructions.

It is located inside or close CPU.Faster than RAM.Data and instruction that are most recently

or frequently used by CPUData and instructions are retrieved from

RAM when CPU uses them for first time.

STORAGE DEVICES Storage devices are used to store data

and programs permanently. Used to store large volume of data and

program. Also called secondary or auxiliary

storage devices. Important functions of storage devices

are reading and writing.

TYPES OF STORAGE DEVICES Magnetic Tape Magnetic Disk

Floppy DiskHard DiskZip Disk

Removable DevicesOptical Devices

CD DVD

Solid State Devices USB Flash Drive Flash Memory

MAGNETIC TAPE Flexible plastic tape coated with

magnetic material Used when large amount of data to be

processed sequentially Very cheap and economical storage

medium Major disadvantage is slow and it is only

sequential

MAGNETIC DISK1. Thin circular metal plate/platter coated with

magnetic material2. Information can be recorded on or read from

magnetic surface3. Disk must be formatted before it can be used4. This process prepares the disk to store data.5. Formatting process creates tracks and sectors

on disk6. Each track is divided into sectors7. Each sector holds a specific number of

characters8. Smallest physical storage unit on disk(512Bytes)9. Every part of hard disk is directly accessible

TYPES OF MAGNETIC DISK 1-Floppy Disk or diskette

Thin plastic disk coated with magnetic material Disk is enclosed in a plastic jacket Stores small amount of data Data access speed of floppy disk is slower than

hard disk. Inexpensive storage media Standard size of floppy is 3.5 inch and its

capacity is 1.44MB A piece of metal covers the reading and writing

area called shutter When disk is inserted the shutters opens to

read the stored data Read/write head is used to read and write data

TYPES OF MAGNETIC DISK 2-Hard Disk

It is called fixed disk because it is fixed in system.

Consists of circular disk called platters sealed inside a container

Containers contains a motor to rotate the disk

Also contains an access arm and read/write head to read and write data

Platter is coated with magnetic material and is used to store data

Provides large storage capacity faster and safer than floppy

TYPES OF MAGNETIC DISK 1.Zip Disk

Portable disk

More storage capacity than floppy disk

Storage capacity is up to 1000MB

Zip disk can be read/write using zip drive

It is used for backing up of large data

OPTICAL DISK TYPES Optical disk uses laser technology to

read and write data Laser stands for light amplification

through stimulated emission of radiation.

Laser beam writes on the surface by creating small holes(PIT) in the disk

Optical drives read data by focusing laser beam on the surface of the disk

TYPES OF OPTICAL DEVICES CD ROM

Stands for compact disk read only memoryData cant be deleted or changed. It is portable storage & transfer data easily. It can store upto 700MB of data. Information can be stored in CD Rom for

many Years.

CD-R Stands for compact disk recordable. User can write data once on CD-R and

read many times. Written data can not be deleted or

changed. CD-R are known as CD burners. Writing information on cd is called CD

burning. CD-R is also Called WORM( Write once

Read Many)

CD-RW Stands for compact disk rewriteable. User can write data on CR-RW many

times by erasing the existing. CD-RW normally used for applications

using large volume with little update activity.

DVD Stands for digital video disk. Similar to CD Rom. It uses laser beam with short wave

length. Data storage capacity is increased. Storage capacity of DVD is much greater

than CD Rom. It can store up 17GB of data.

SOLID STATE STORAGE DEVICES USB FLASH DRIVE

Also known as pen or keychain drive.Provide greater capacity than floppy or zip

disk. Its capacity can be GBSmall and light weight storage device. It is durable and can be carried on a key

ring. It can be plugged into any USB port.

FLASH MEMORY CARDS Flash memory cards is used in PDA,

Digital Camera, Cell Phones and notebook computers.

These cards are not interchangeable.

SOFTWARE A set of instruction given to computer to

solve a problem is called software. Also known as program. Computer software specify a sequence

of operations to be performed by computer.

A computer works according to the instructions written in software.

TYPES OF SOFTWARE The main types of software are system

software and application software.

System software

Application software

SYSTEM SOFTWARE System software is a set of programs to

control and manage the actual operations of a computer hardware.

It controls the usage and allocation of different hardware components.

It enables application programs to execute properly

Examples of system softwareOperating systemUtility programsDevice drivers

APPLICATION SOFTWARE Application software

A program needed to perform various applications on the computer by user

It helps a computer user to solve specific problems

Application software uses operating system in order to function

Application software runs on the top of the operating system software.

Example Word Processor Spread sheet Graphics Database