IO Devices and Storage Devices

Input Devices• Input devices are those devices from

which we can input data and instructions into the computers. A number of input devices have been developed.

Input devices

keyboard

KEYBOARDIt is most commonly used input device. It is used to input data into written form. Keyboard is merely a collection of momentary switches.

Input devices

keyboard

Input devices

keyboard

Normalkeyboard

NORMAL KEYBOARD• A normal keyboard has 101-104 keys

which are distributed in five categories.• Function keys

F1 to F12• Alphanumeric keys

A-Z, a-z, 0-9• Special keys

Alt, Ctrl, Enter, Insert, Home, End, Esc etc.

• Numeric keypad 0-9,+,-,*,%,@ etc.

Input devices

keyboard

Normalkeyboard

Multimedia keyboard

MULTIMEDIA KEYBOARD

• Multimedia keyboard has some additional keys to operate multimedia operations like volume up, volume down, play, pause, stop etc.

Input devices

keyboardmouse

Normalkeyboard

Multimedia keyboard

MOUSE• It is a pointing device used to

insert instructions into the computers. It is a hand held device that controls the pointer on the screen. It has two buttons viz. left button & right button & one scrolling wheel. With the help of mouse you can draw images, select options & move text & images.

Input devices

keyboardmouse

Normalkeyboard

Multimedia keyboard

Traditional mouse

TRADITIONAL MOUSE

• Traditional mouse is used a ball built into the bottom with two small rollers placed two sides of the ball at 90 degree angle from each other. They spin when the ball rolls. A sensor detects how much each roller spins and sends the information to computer and the pointer on the screen moves into the same direction.

Input devices

keyboardmouse

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

OPTICAL MOUSE• Optical mouse is a advance

pointing device that uses a light diode (LED)(1), an optical sensor (2) and a digital signal (3) processing in place of traditional mouse ball. Optical mouse need plan surface to produce high performance efficiency. Each time the mouse is moved, the beam of light is interrupted by the surface.

Input devices

keyboardmouse

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

Input devices

keyboardmouse

joystick

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

JOYSTICK• Joystick is a pointing device

mostly used for playing games. This is a device used to control the actions in a computer game. It consist of a lever used to move the pointer on the screen and buttons used to select options.

Input devices

keyboardmouse

joystick

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

Input devices

keyboardmouse

joystick

Touch screen

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

TOUCH SCREEN• Touch screen is the easiest way

to data input into computer. Touch screen allows the user to select the item by touching the screen at appropriate spot. It has another feature that the user’s finger become the input device to operate touch screen.

Input devices

keyboardmouse

joystick

Touch screen

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

Input devices

keyboardmouse

joystick

Touch screen

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

microphone

MICROPHONE• Microphone is an input device

used to inputting the voice signal into the computer. microphones are commonly used for live chat. Microphones are also used to record voice into the computer.

Input devices

keyboardmouse

joystick

Touch screen

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

microphone

Input devices

keyboardmouse

joystick

Touch screen

microphone

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

scanner

SCANNER• Scanner is an input device used

to insert a picture into the computer. This is a peripheral device that converts a printed image into digital information. There are two types of scanners:

Input devices

keyboardmouse

joystick

Touch screen

microphone

scanner

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

Flat bed scanner

Hand held scanner

FLAT BED SCANNER

• A flat bed scanner uses a flat surface just like photocopier. We can place a picture on the surface of the scanner:; scanner scans the image and convert into digital form. The picture can be seen on the monitor screen after scanning.

Input devices

keyboardmouse

joystick

Touch screen

microphone

scanner

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

Flat bed scanner

Hand held scanner

Input devices

keyboardmouse

joystick

Touch screen

microphone

scanner

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

Flat bed scanner

Hand held scanner

Bar code reader

Bar code reader

• Bar code reader are used to read the values printed on the product in form of vertical lines. Bar codes are recorded on the products by the manufacturers and usually carry the product number.

Input devices

keyboardmouse

joystick

Touch screen

microphone

scanner

Normalkeyboard

Multimedia keyboard

Traditional mouse Optical mouse

Flat bed scanner

Hand held scanner

Bar code reader

OUTPUT DEVICES

What are OUTPUT DEVICES?

- Output devices are hardware devices that display or present information to the user or other people. The monitor, printer and the speaker are one of the examples.

MONITOR

MONITOR

- The monitor is a visual display device to present output information in the form of text, graphics, or video on the monitor screen.

MONITOR

- There are two kinds of monitor; the flat panel or LCD (Liquid Crystal Display) monitor and the older CRT (Cathode Ray Tube) models.

CRT (Cathode Ray Tube)

- It is basically a vacuum tube with an electron gun and a fluorescent screen. A coating of red, green and blue are used to form images in the form of light emitted from the fluorescent screen.

CRTMONITOR

TFT LCD (Thin Film Transistor Liquid Crystal Display)

- LCDs are thin, flat display device made of color pixels arrayed in front of a light source (backlight) or reflector. The advantage of LCD monitors is less space, low power and low radiation.

TFTLCD

PRINTER

PRINTER

- It is a computer device that produces a permanent copy on paper of information from the computer. There are several kinds of printers: ink jet, dot-matrix and laser jet printers.

DOT MATRIX PRINTER

- Prints by hammering or striking an ink-soaked cloth ribbon against a paper. The advantage of this kind of printer is that it can easily create carbon copies because of the impact action of the printing process. The cost per page of printing is relatively cheap.

DOTMATRIX

INK JET PRINTER

- Operates by propelling or spraying different sizes of very small and precise amount of ink onto a paper or other media. Printing quality of this printer is better than the dot matrix.

INK JET PRINTER

- The ink comes form a cartridge of liquid ink and this printer is simply black and white or in full color.

INKJET

LASER JET PRINTER

- It produces high quality prints or graphics on paper. Color and black and white printing is available. It is based on the principle of electrostatic printing and photography wherein the source of ink is a toner.

LASERJET

PLOTTER

- It comes in 2 types: pen plotter and electrostatic. Pen plotter is a vector graphics printing device which operates by moving a pen over the surface of paper.

PLOTTER

- It is usually used for large printing requirements of CAD drawings of houses, buildings, cars, airplanes and others. It is also used for vinyl and plastic used for billions and posters.

PLOTTER

THERMAL PRINTERS

- Produce prints on thermal paper by selective heating wherein heated areas turns black creating an image. It is mostly used in groceries and department stores. They print faster and quieter than dot matrix.

THERMALPRINTER

SPEAKERS

SPEAKER

- It is an output device for sounds music, audio from movies and computer alerts are heard from this device. There are several speaker system for computer, from 2 piece simple system to as man as 5 and more speakers.

HEADPHONE

HEADPHONE

- It is a small speaker with a way to hold them close to the ears of the user. The headphone allows the user to listen music and sounds all alone.

DATAPROJECTOR

DATA PROJECTOR

- It displays computer information on big screen so that many will able to see the show.

STORAGE DEVICES

CD-ROM - CD Read Only Memory. When you buy the disk, it already has the data or program stored on it. You can read it, but can't save to it. For example would be a music CD.

CD-WORM - CD Write Once Read Many. This means that you are able to save to this disk one time, so you can store your data or an application on it. However, once you have saved onto the disk once, you can access the data many times but can't save onto it again.

CD-RW - CD Read Write. This means that you can save data to your disk over and over again, just like you can with a floppy disk.

Optical Storage Devices- CDCompact disks are known as optical storage devices. Data is

burned onto the surface of the disk using a laser beam in the CD drive. A laser beam is also used to read the data stored on the disk.

A typical CD can store around 650 Mb of data - equivalent to 450 floppy disks.

Advantages Small and portable Very cheap to produce Fairly fast to access the data

- quicker than a floppy disk or magnetic tape

Disadvantages× Fairly fragile, easy to snap or

scratch × Smaller storage capacity

than a hard drive or DVD × Slower to access than the

hard disk.

Optical Storage Devices-DVD• DVDs are amongst the most common methods of

copying and backing up data at home.• A DVD is similar to a CD in that it is an optical device

and that a laser is used to store the data and read the data.

• A single sided DVD can store about 4.7Gb of data. DVDs which store data on both sides can hold over 9Gb of data.

Advantages

Very large storage capacity

Sound and picture quality is excellent, making them ideal for storing films with video and sound.

DVDs are now mass produced so they are relatively cheap

DVD players can read CDs

Disadvantages

× DVDs do not work in CD drives

× There is no single standard of DVD

× They can be easily damaged by breaking or scratching

CD Rom & DVD Rom Application which require the prevention of deletion of

data accidental .CDs use by software company for distributing software programs and data, by Music companies for distributing music albums and by book publishers for distributing reference books.DVD used by film distributor.

Advantage : Can store data permanently Not expensive

Disadvantage :× Cannot edit or delete data

Applications which require a single ‘burning’ of data, e.g. CDs– recording of music downloads from the Internet, recording of music from MP3 format, recording of data for archiving or backup purposes. DVDs – recording of film movies and television programs

Advantage :Light and thinNot expensiveFast responding

Disadvantage :×Single Burning ×Can be written once

CD R & DVD R

CD RW & DVD RW Applications which require the updating of information

and ability to record over old data. Not suitable for music recording but is very useful for keeping generations of files. DVDs have between five and ten times the capacity of CDs.

Advantage : Hold 650 mb of data 74 mins of audio Less expensive than Blu-ray and HD-DVD

Disadvantage :× Slower to write

Blu-ray is a high-density optical disc format similar to DVD. Blu-ray is the type of disc used for Playstation 3 games and for playing high-definition movies, formerly competing against the now obsolete HD DVD format. One dual-layer Blu-ray disc can store up to 50GB (gigabytes) of data. That is five times more than a DVD, and 70 times more than a CD or VCD.

Advantage : Greater storage space allows for greater amounts of

information on one disc this results in the ability to carry 7.1 surround

Support from more movie studios Uncompressed soundDisadvantage :× More expensive than HD DVD

Blu-ray

Floppy disks are one of the oldest types of portable storage devices still in use.

A floppy disk can store up to 1.44 Mb of data which is equivalent to around 300 pages of A4 text. They used to be the ideal storage device for transferring small files from home to work/school or from one office computer to another. But nowadays, many files contain graphics that are larger than the size of the floppy disk.

Floppy disks are a magnetic storage device. All disks must be formatted before data can be written to the disk.

Formatting divides the disk up into sections or sectors onto which data files are stored.

Magnetic Storage Devices-Floppy Disk

Advantages

Portable - small and lightweight ,inexpensive

Useful for transferring small files between home and school

Security tab to stop data from being written over

Can be used many times

Disadvantages

× Not very strong - easy to damage

× Data can be erased if the disk comes into contact with a magnetic field

× Quite slow to access and retrieve data when compared to a hard disk

× Can transport viruses from one machine to another

× Small storage capacity

Solid State Devices – Flash memory card &Memory stick

Flash memory storage devices are typically small, lightweight, removable and rewritable. They consist of a small printed circuit board which is encased in plastic or metal casing. They usually have a removable cap which covers and protects the part of the stick which is inserted into a USB port.

Memory stick are available from 1GB up to 8GB

Advantages They are more compact than floppy disks or CDs/DVDs.

They hold more data than a floppy disk, nowadays often more than a CD.

They are being developed with fashionable looking outer casings and are almost becoming a 'fashion accessory.

Disadvantages

× The cost per megabyte of storage is more expensive than floppy disks, CDs or DVDs.

× They can be easily lost .

× The metal part which is inserted into the USB port can be snapped off if they are handled roughly.