Chapter-2
INPUT AND OUTPUT DEVICES
INPUT DEVICE: The hardware device that allows data to be input
into a computer.
1- KEYBOARDS: It is used to input text. Most commonly use is
QWERTY. Ergonomic layout is used to avoid muscle strain.
USES:
a- Input data into application software such as word
processor.
b- Typing in commands to the computer.
Advantages:
a- Easy to use for most people.
b- Fast entry of new text into a document.
Disadvantages:
a- Slower data entry as compared to OMR reader.
b- Take desk space.
c- Difficult to use for handicapped people.
2- CONCEPT KEYBOARD: It has icons or phrases instead of
standard letters.
INPUT AND OUTPUT DEVICES
USES:
a- Fast food restaurants.
b- Where limited range of choices is available.
Advantages:
a- Allow fast entry of data as compared to standard keyboard.
b- Waterproof.
c- Easier to give commands.
Disadvantages:
a- Only limited instructions can be given.
b- Limited options are shown on the keyboard.
3- NUMERIC KEYPAD: It has number keys only.
USES:
a- In Automatic Teller Machines (ATMs) to input the amount
of money.
b- AT POS to input amount manually.
c- On CHIP and PIN machines to enter the amount of money.
Advantages:
a- Faster than standard keyboard.
b- Easy to carry around as they small devices.
INPUT AND OUTPUT DEVICES
Disadvantages:
a- Small keys can make input more difficult.
b- Order of the numbers can be different.
2- POINTING DEVICES :
1- MOUSE: It controls the position of a pointer on the screen.
USES:
a- Opening, closing and minimizing the software.
b- Moving or deleting the folders.
Advantages:
a- Does not need a large desk.
b- Quickly move on the screen.
c- Faster way to choose an option.
Disadvantages:
a- Difficult to use for handicapped people.
b- Does not work on shiny or uneven surface.
INPUT AND OUTPUT DEVICES
2- TOUCHPAD: In laptop computers the pointer is controlled
by the user moving their finger on the touchpad. Its uses are
the same as those of mouse.
Advantages:
a- As it is integrated into the laptop computer there is no need
for a separate mouse.
b- Faster than keyboard for choosing option.
Disadvantages:
a- Difficult to use for people having limited hand/wrist
movement.
b- Often difficult to use during drag and drop.
3- TRACKERBALL: Same as mouse except the ball is on the top
or the side of the device.
USES:
a- Used in applications where user has a disability.
b- Used in a control room environment to navigate through.
c- Often used in luxury cars to select feature.
Advantages:
a- Does not need same fine control as mouse.
INPUT AND OUTPUT DEVICES
b- Easier to use than mouse for disabled persons.
c- More accurate positioning of the pointer.
d- Needs less desk space.
Disadvantages:
a- Not available with standard computers.
b- User may need a training.
3- REMOTE CONTROL: A keypad used to control other devices
remotely.
USES:
a- It is used in television, satellite system, DVD players etc to
control and alter the functions.
b- Used in industrial applications to remotely control
processes.
Advantages:
a- Can be operated from a reasonable distance.
b- Can be used in hazardous places to control processes.
INPUT AND OUTPUT DEVICES
Disadvantages:
a- Difficult to use if operator has limited hand/wrist
movement.
b- Its signals can be easily blocked.
4- JOYSTICKS: By gripping the stick a pointer on the screen can
be controlled, buttons are used to make selections.
USES:
a- Used in video/computer games.
b- Used in simulators.
Advantages:
a- Easier than keyboard to navigate the screen.
b- Control is more realistic than using a mouse.
Disadvantages:
a- Difficult to use it other than playing video games.
DRIVING WHEEL: A steering wheel similar to a joystick in
many ways. It connects to a computer using a USB. Its uses
are same as that of joystick
INPUT AND OUTPUT DEVICES
Advantages:
a- Easier than keyboard or joystick.
b- Driving experience is nearer to reality.
Disadvantages:
a- Expensive.
b- Movement can be too sensitive.
5- TOUCH SCREENS: User can choose an option simply by
touching a button/icon on the screen without any pointing
device.
USES:
a- Self-service tills.
b- ATMs.
c- POS.
d- Interactive white boards.
e- Computer based training where answers are selected
during on screen testing.
f- Mobile phones and tablets screens.
Advantages:
a- Faster entry of options than using keyboard or mouse.
INPUT AND OUTPUT DEVICES
b- Easy to choose options.
c- User friendly.
Disadvantages:
a- Screen can get dirty, this reduces its responsiveness.
b- Limited number of options on the screen.
6- SCANNERS: They enter the information from hardcopy into
the computer in the form image.
USES:
a- Scan in documents and convert into a format for use in
various software packages.
b- Scan in old/valuable document/book, thus saving it into
digital format.
c- Scan in photographs and can be sent via internet.
Advantages:
a- Images or text can be stored in digital format and can be
editing at a later date.
b- It is possible to recover damaged documents.
INPUT AND OUTPUT DEVICES
Disadvantages:
a- Quality can be limited depending on the resolution of the
scanner.
b- Can be slow sometimes if the color scanning chosen
resolution is high.
7- DIGITAL CAMERAS: It takes the photographs and images
and stores in a memory card. It has replaced the traditional
film based cameras.
Advantages:
a- Easier to produce better-quality photographs than
traditional camera.
b- No need to develop film.
c- Memory cards can store several photographs.
d- Easily connectable to the computer using USB.
Disadvantages:
a- Need to be computer literate for taking pics and
transferring them into computers.
b- Loss of photographic artists.
c- The resolution is not still good.
INPUT AND OUTPUT DEVICES
VIDEO CAMERA: It is capable of taking moving images thus
video is simply a footage of still photos stitched together.
Advantages:
a- Video footage can easily be manipulated.
b- DVD format gives a very high quality image.
Disadvantages:
a- Expensive.
b- Memory card storage capability is not high.
8- MICROPHONES: It converts sound into electrical signal.
USES:
a- To input speech/sound to be used in various applications.
b- Input speech/sound in voice-recognition software.
c- It can also be used as sensor to pick up sound in burglar
alarm.
Advantages:
a- Faster to read text than to type it using keyboard.
b- Sound can be manipulated easily using special software.
INPUT AND OUTPUT DEVICES
c- Voice-recognition system improves the security of a
system.
Disadvantages:
a- Sound files can take a lot of memory.
b- Voice-recognition software is not as accurate as typing
manually.
9- SENSORS: A device which measures a physical quantity and
inputs the data to a computer.
USES:
a- It is used in control and monitoring systems such as burglar
alarm system, greenhouse control system etc.
b- It helps in controlling a hazardous chemical reaction or
process.
Advantages:
a- Takes more accurate reading as compared to human being.
b- Readings are continuous.
c- Can be used remotely as well as at hazardous place.
Disadvantage:
a- Faulty sensor can give false readings.
INPUT AND OUTPUT DEVICES
10- GRAPHIC TABLET: The device used with stylus produces
freehand drawings.
USES:
a- Used to produce computer graphics or computer-aideddesigns.
b- It is easier to input complex language as compared to
keyboard.
Advantages:
a- Drawing can be modified before the input to the computer.
b- Often offer very accurate method of drawing.
c- It can record level of pressures unlike other point and click
devices.
Disadvantages:
a- Expensive.
b- It may take longer time to draw by using stylus.
c- Difficult to produce larger drawings,
d- Screen can be damaged easily.
INPUT AND OUTPUT DEVICES
13- WEBCAMS: It is similar to video cameras, however, they
are connected directly to the computer and don’t have the
memory.
USES:
a- It is used as a personal way of having communication.
b- It enables video conferencing.
Advantages:
a- Provides immediate face to face video chat for
conferences etc.
b- People can keep in contact without traveling.
Disadvantages:
a- Limited features, often have poor quality.
b- Need to be connected with the computer.
12- LIGHT PENS: This device only work with CRT monitors,
and they contain sensors that send signal to a computer
whenever light changes are detected.
USES:
a- Selecting the objects on CRT screens.
b- Drawing on screen.
INPUT AND OUTPUT DEVICES
Advantages:
a- Greater accuracy than touch screens.
b- Small in size.
c- Easy to use.
Disadvantages:
a- Lags when drawing on the screen.
b- Only works with CRT monitors.
DIRECT DATA ENTRY DEVICES
1- DEVICES FOR READING INFORMATION FROM CARDS
1- MAGNETIC STRIP READER: These devices read useful
information from the magnetic strip found on the back of
debit or credit cards etc.
USES:
a- On credit/debit cards for use at ATMs, EFTPOS terminals.
b- Security devices to allow entry to building, hotel rooms
etc.
Advantages
a- Faster to enter data as compared to keyboard.
b- Error free entry.
c- Secure because nobody can observes the entered data.
INPUT AND OUTPUT DEVICES
d- Prevents access to secure area.
e- Not effected by oil, water and moisture etc.
Disadvantage
a- If magnetic stripe gets damaged.
b- Does not work at a distance.
c- Since the information is not readable, this can be a
disadvantage.
2- CONTACTLESS CARD READER: It allows debit or credit
cards customers to pay worth up to $25 without entering
their PIN. It has small chip that emits radio waves in
them.
HOW IT WORKS:
a- Shop worker enters the amount for payment.
b- The card reader informs the customer to present his
contactless card.
c- Customer holds the card in front of the card reader.
d- The terminal display will show that the card has been
read.
INPUT AND OUTPUT DEVICES
Advantages:
a- Faster transaction.
b- Customers do not have to worry about typing and
remembering the PIN
c- Retailors have no access to the customer’s debit/credit
card.
d- The card does not give information about the customer’s
account number.
Disadvantages:
a- Expensive than normal credit/debit card.
b- Can take money twice if customer does not place the card
properly on the card reader.
c- Transactions are usually limited to small value.
3- CHIP and PIN READERS: This device has slot into which
card is placed and chip is read. The PIN is entered using
the keypad.
USES:
a- It is used at EPOS where payments are made using cards.
INPUT AND OUTPUT DEVICES
Advantages:
a- More secure system than contactless card reader.
b- Faster than magnetic stripe cards.
Disadvantages:
a- Fraud can happen if somebody steals the PIN number.
2- RADIO FREQUENCY IDENTIFICATION (RIFD) READER: It use
radio waves to read and capture information stored on a
tag. The tag can be read from a distance. Tag consists of a
microchip and an antenna.
USES:
a- Livestock tracking and observe the whereabouts of each
animal.
b- Retail shop.
c- Admission and tracking f people in a park etc.
d- In Libraries books can be tracked in and out easily.
Advantages:
a- Tags can be read from a distance.
b- It is robust and reliable.
c- Information can be read and written.
d- Bulk detection is possible.
INPUT AND OUTPUT DEVICES
Disadvantages:
a- Radio waves can be interrupted.
b- It is easier to hack.
c- It is expensive.
3- MAGNETIC INK CHARACTER RECOGNITION READER
(MICR): This device can read characters printed in a special
ink.
USES:
a- It is used reading characters at the bottom of bank cheques.
Advantages:
a- Great security than OCR.
b- Errors are reduced as there is no manual input.
c- Ink can be read even if somebody writes on it.
Disadvantages:
a- Only certain characters can be read.
b- Expensive method of data entry
4- OPTICAL
MARK RECOGNITION READER (OMR): It reads
marks written in pen or pencil. The position of the mark is
saved in computer’s memory after being read by the OMR
device.
INPUT AND OUTPUT DEVICES
USES:
a- Used to read MCQs papers and Questionnaires.
Advantages:
a- Accurate way of getting input.
b- Very fast way of inputting results of a survey or MCQ paper.
c- More accurate than OCR.
Disadvantages:
a- Forms need to be carefully designed.
b- If the forms have not filled properly problem in reading may
occur.
5- OPTICAL
CHARACTER RECOGNITION/READER (OCR): It
takes scanned text and converts it into a computer readable
form.
USES:
a- Scanned text can be used in various application software
such as word processor.
b- Reading and processing passports and identity cards.
INPUT AND OUTPUT DEVICES
Advantages:
a- Faster way of getting input as compared to manually entry.
b- More accurate.
Disadvantages:
a- Sometimes its very difficult to read bad handwriting.
b- Still not highly accurate technique.
COMPARISON of OCR and OMR
OCR
OMR
It reads handwriting, so It involves
customers can write answers information
in their words.
limited.
shading
obtained
so
is
This
method
reads It detects the mark or
handwriting, however, poor shading, however, improper
handwriting may cause filling may cause reading
reading errors.
errors.
It converts printed document It simply reads position of the
to an editable electronic mark.
format.
It
requires
complex It requires complex and
recognition system
expensive forms to be filled.
INPUT AND OUTPUT DEVICES
6- BARCODE READERS: It reads the information in the form of
a barcode. A barcode reader scanner is used to read the
information.
USES:
a- Used at supermarkets, POS and other shops where the
goods are marked with barcode.
b- Used in libraries to keep track of books on loan.
c- Used in warehouses for identifying and counting the items.
Advantages:
a- Much faster to enter items in stock.
b- Accurate way of billing at any POS.
c- Faster way of identifying items in a stock
Disadvantages:
a- Relatively expensive system to administer as compared to
manual system.
b- Not a fool proof system.
c- Can be easily damaged than RIFD or magnetic strips.
d- It holds less data as compared to QR code.
INPUT AND OUTPUT DEVICES
7- QUICK RESPONSE CODES (QR): It is made up of a matrix of
filled in dark squares on a light background. The code may
contain a website link or some form of advertising. It can be
easily scanned through mobile phone built-in camera or
through appropriate application.
USES:
a- It stores advertising links or item lists.
Advantages:
a- It can store advertising website addresses/URL that appear
in magazines, trains, buses or even business cards.
b- User does not need to provide or key in the website
manually.
Disadvantages:
a- QR code has to be scanned through camera.
OUTPUT DEVICES AND THEIR USES
MONITORS:
1- CATHODE RAY TUBE MONITORS (CRT): A CRT
monitor contains millions of tiny red, green, and blue
phosphor dots that glow when struck by an electron beam.
USES:
INPUT AND OUTPUT DEVICES
a- Primary output device for computers.
b- Used with light pens.
Advantages:
a- Angle of viewing is still better than with most TFT monitors.
b- They work with light pens in CAD/CAM applications.
Disadvantages:
a- Heavy and large in size.
b- They run very hot especially as they get old.
c- Consumes more power than TFT monitors.
d- They can flick a lot.
2- THIN FILM TRANSISTOR MONITORS (TFT): The screen is
made up of thousands of pixels, each pixel has three
transistors colored red, blue and green controlled by a
microprocessor.
USES:
a- Integral part of laptop.
b- Primary output device for computers.
Advantages:
a- Lightweight.
b- Consumes less power as compared to CRT monitors.
INPUT AND OUTPUT DEVICES
c- Produce less glare and emit less radiation.
Disadvantages:
a- The viewing angle is not that great.
b- Definition is sometimes not as good as CRT monitors.
3- LIQUID CRYSTAL DIODE/DISPLAY (LCD): The front layer of
the monitor is made up of liquid crystal diodes which are
grouped together and known as pixels. They use CRT as the
backlighting method.
4- LIGHT EMITTING DIODE/DISPLAY (LED): These are the
modern LCDs which use light emitting diode as backlighting.
5- ORGANIC LIGHT EMITTING DIODE (OLEDs): They use
organic material. They do not use any backlighting.
6- MUTIMEDIA PROJECTORS: It receive signals from a
computer, television or DVD player. The image is magnified
and projected onto a large screen.
USES:
a- Home cinema systems.
b- Training presentations.
c- Advertising presentations.
INPUT AND OUTPUT DEVICES
Advantages:
a- Enables many people to see a presentation.
b- Avoids the need for several network computers showing
the same video.
Disadvantages:
a- Images can sometimes be fuzzy.
b- Expensive to buy the outset.
c- Setting up projectors can be little difficult.
3- PRINTERS
1- LASER PRINTER: It includes a positive charge drum and
negative charge toner. They have large buffer memories
where data is stored before pages can be printed.
USES:
a- It is used where high quality and high volume printing is
required.
b- They are used where low noise is required.
Advantages:
a- Fast printing.
INPUT AND OUTPUT DEVICES
b- Bulk printing can be possible.
c- Printing quality is high.
d- Toner cartridges last for a long time.
Disadvantages:
a- Color laser printer is expensive.
b- Use organic compounds and have been linked to the health
hazards in the office.
c- Only fast if several copies are made.
2- INKJET PRINTERS: It sprays the ink onto the paper to
produce a hard copy.
USES:
a- Used where low volume of printing is required.
b- They are good at producing photo-quality print outs.
c- 3-D inkjet printers are now being used in industry.
Advantages:
a- High quality output.
b- Less expensive than laser printers.
c- Lightweight.
d- Does not produce volatile organic compounds.
INPUT AND OUTPUT DEVICES
Disadvantage:
a- Slow output if bulk volume is printed.
b- Ink cartridge run out too quickly.
c- Can be expensive if used a lot.
3- DOT MATRIX PRINTERS: It a type of impact printer where a
print head presses against an ink ribbon.
USES:
a- They can be used in noisy environments.
b- Printing carbon copies.
Advantages:
a- Very cheap to run and maintain.
b- Easy to use if continuous printing jobs are required.
c- Does not affected by dust as compared to laser printer.
Disadvantages:
a- Very slow.
b- Poor quality.
c- Very noisy.
INPUT AND OUTPUT DEVICES
4- 3-D PRINTERS: It is based on inkjet or laser printer
technology but builds a 3-D object layer by layer using
material such as powdered metal, paper or ceramic.
USES:
a- Prosthetic limbs can be made to fit exactly on to the injured
body.
b- Used in precise reconstruction surgery i.e. facial
reconstruction.
c- Aerospace manufacturing.
d- Fashion and art 3-D printing.
e- Manufacturing industry.
HOW 3-D PRINTER WORKS:
1- A design is made using CAD.
2- The design is imported into a special software from where
3-D printer can understands the design.
3- The 3-D printer is set up to allow the solid object to be
made.
4- The object is built up layer by layer.
5- The object is removed from the printer and is then may be
given final touch by hand sometimes.
Advantages:
a- Customized products can be manufactured.
INPUT AND OUTPUT DEVICES
b- It manufacture accurate, precise and relatively quickly.
c- It produces artificial limbs.
d- It saves labor cost.
Disadvantages:
a- Expensive.
b- In the hands of wrong people can lead to dangerous and
illegal activities.
c- People can lose jobs due its commercial use.
4- SPEAKERS: It produces a sound output. The sound data
from the computing device is converted into analogue using
DAC card and then speakers produce output.
USES:
a- Output sound from multimedia presentation.
b- Play downloaded sound files.
c- Audio output of text from the screen.
5- CONTROL APPLICATIONS
ACTUATORS: These are transducers which take signals from
computer and convert them into some form of motion.
They are primarily used in control processes to perform
some specific functions according to their build up.
TYPES OF ACTUATORS:
1- MOTORS: It is turned on or off by the actuator.
INPUT AND OUTPUT DEVICES
USES:
a- Automatic washing machines.
b- Control of robot movement.
c- Control of water pumps in central heating systems.
2- BUZZERS: The buzzers are switched on or off by the
actuator.
USES:
a- Used in burglar alarm.
b- Used in control applications to tell the operator something
wrong has happened or times up.
3- HEATERS: The actuator is connected to switches that turn
the heater on or off.
USES:
a- Automatic temperature control applications such as room,
oven or hot plate.
b- Automatic washing machines to heat up the water if
necessary.
c- Heat control in automatic glasshouse.
4- LIGHTS: The actuator is connected with a switch which
turns on or off the light.
USES:
a- Security lights.
b- Automatic glasshouse to control the light.