Useful for B. Sc. Ag. Students

1. Md I A Ansari
BAU, Ranchi

2. • The input/output devices provide the means
of communication between the computer and
the user.
• They are also known as peripheral devices
because they surround the CPU and the
memory of a computer system.
• Input devices are used to enter data from the
user into primary storage, and output devices
supply the results of processing from primary
storage to the users.
• Output devices translate the computer's
output into the form understandable by users.

3. Input Devices
• The devices which are used to input the
data and the programs in
the computer are known as "Input
Devices".
• An input device is an electromechanical
device which accepts data from the users
and translates them into a form which the
computer can interpret.

4. • Some popular input devices are keyboard,
scanner, mouse, touch screen, electronic
card reader, digitizer, light pen , track ball,
bar code reader, microphone, Magnetic
Ink Card Reader(MICR), Optical Character
Reader(OCR), etc.

7. Mouse
• It is called pointing device which is used to
point to the things on the monitor screen.
• It is a device that controls the movement of
the cursor on a monitor.
• It is the main way to interact with computer.
• Generally it has two buttons called left and
right button and scroll bar is present at the
mid.
• Mouse can be used to control the position
of cursor on screen and used to select the
options on the screen.

8. • It was invented by Douglas Engelbert of the
Stanford Research Institute in 1963.
• There are three types of mouses: two-button
mouse, three-button mouse and optical mouse.
• A two-button mouse has right and left
buttons, a three-button mouse has right, left
and center buttons and optical mouse has right,
left buttons and a scroll wheel at the centre.
• There are four mouse actions: Click, Double
click, Right click and Drag
and Drop.

9. • Microphone: A microphone is used to record
any voice or sound into
the computer.

10. • Light Pen: Light pen is a pointing device
which is similar to a pen.
• This is an input device which is used to
draw lines or figures on a computer
screen.
• It is used to
directly write and draw any figure on the
computer screen.

11. • Track Ball: Track ball is an input device
that is mostly used in notebook or laptop
computer, instead of a mouse.
• A track ball comes in various shapes like a
ball, a button and a square. It is mainly
used in the CAD, CAM.

12. • Digital camera: A type of camera that
stores the pictures or video it takes in
electronic format instead of to film.

13. • Web Camera: A web camera is used to view
images on the Internet.
• Using it with the help of Internet we can
view the photo of a far away person, but he should also
have a web camera.
• It is like a digital camera which is used
as an input device by adding to the computer.
• It capture
images in digital formate that can be easily transferred
into a computer and manipulated using graphics
software.

14. • Keyboard: Most common and very
popular input device is keyboard.
• The data and instructions are input by
typing on the keyboard. The message
typed on the keyboard reaches
the memory unit of a computer.
• The keyboard helps in inputting the data to
the computer.

15. • Scanner: Scanner is an input device
which works more like a photocopy
machine.
• An optical scanner is a device used to
read an image, convert it into binary codes
and stored in a computer’s memory. The
image may be a handwritten document, a
typed or printed document or a picture.
Flat bed scanner is the most popular
optical scanner.

16. • Digitizer: A digitizer tablet (also known as
a digitizer or graphics tablet) is a tool used
to convert graphics and pictorial data into
binary inputs. A graphic tablet is a
computer input device that enables a user
to hand-draw images.

17. • Touchpad: A touch pad is a device for
pointing on a computer display screen.
• It is an alternative to the mouse.
• Originally incorporated in laptop
computers, touch pads are also being
made for use with desktop computers.
• A touch pad works by sensing the user’s
finger movement and downward pressure.

18. • Magnetic Ink Card Reader (MICR): MICR
input device is a character recognition
technology used primarily by the banking
industry to facilitate the processing of the
cheques.
• This reading process is called Magnetic Ink
Character Recognition (MICR).
• MICR provides a secure, high speed of
scanning and processing information.

19. • Optical Character Reader (OCR): OCR
is an input device used to read a printed
text. OCR scans text optically character by
character, converts them into a machine
readable code and stores the text on the
system memory.
• This is used in office atomization,
documentation in library etc.

20. • Bar Code Readers: Bar Code Reader is a
device used for reading bar coded data
(data in form of light and dark lines).
• Bar coded data is generally used in
labelling goods, numbering the books etc.
This is used in super markets, book shops
etc.

21. • It may be a hand held scanner.
• Bar code reader scans a bar code image,
converts it into an alphanumeric value
which is then fed to the computer to which
bar code reader is connected.

22. • Optical Mark Reader (OMR): OMR is a
special type of optical scanner used to
recognize the type of mark made by pen
or pencil.
• It is used where one out of a few
alternatives is to be selected and marked.
It is specially used for checking the
answer sheets of examinations having
multiple choice questions.

23. • Touch Screen: It allows the user to
operate/make selections by simply
touching the display screen.
• A display screen that is sensitive to the
touch of a finger.
• It is the most preferred human computer
interface devices used in information
kiosks.

24. • An information kiosks is an unattended
system which is used to store information
of public interest and allows people to
access the stored information as per their
requirement.
• It may be located at an airport, railway
station, zoo etc. In touch screen, input is
given through the computer screen that
accepts input through monitor.
• Users touch electronic button displayed on
the screen.

26. • Output Devices: An output device is an
electromechanical device which accepts
data from a computer and translates them
into a form that can be understood by the
user.
• Some popular output devices are: monitor,
printer, plotter, speaker, screen image
projector, voice response systems etc.

27. • Monitor: Monitor is by far the most popular
output devices used today for producing
soft-copy output.
• It is also known as Video Display Unit
(VDU).
• The sharpness of the image depends upon
the no. of the pixels.
• The higher the pixel count, the higher the
"resolution."
• Common resolution settings are 640 x 480,
800 x 600, 1024 x 768, 1280 x 1024, etc.
1,280 pixels wide and 1024 pixels tall.

28. • Monitors come in different sizes.
• The (most important) size of the monitor is
measured diagonally on the screen and is
given in inches. Based on this, monitors
range in sizes of 12", 14", 15", 17", 19",
21", 29", etc.

29. • Types of computer monitors
• CRT (cathode ray tube) monitors. These
monitors employ CRT technology, which
was used most commonly in the
manufacturing of television screens.
• LCD (liquid crystal display) monitors.
• LED (light-emitting diodes) monitors.

30. • Cathode-Ray Tube (CRT) Monitor: CRT
(Cathode Ray Tube) Monitors are built
very similarly to older (tube) television
sets.
• In the CRT display is made up of small
picture elements called pixels for short.
• The most screens are capable of
displaying 80 characters of data
horizontally and 25 lines vertically.
• CRT monitor is large in size and consume
more power.

31. • Flat-Panel Display Monitor: Power
requirement is less as compared to the
CRT.
• Current uses for flat-panel displays include
monitors, laptop computer, graphics
display.
• The flat-panel displays are divided into two
categories: LCD and LED
• LCD (Liquid Crystal Display) Monitors are
thin and flat. They are light, compact, take
up very little desk space emit no known
radiation

33. • Printer: Printer is the most important output
device.
• It is a device that produces content available on
screen on the paper. Printing quality is
expressed in DPI. It stands for "Dots Per Inch."
• DPI is used to measure the resolution of an
image both on screen and in print.
• The two types of printers are:
• Impact Printers and Non-Impact Printers. Dot
Matrix Printers, Daisy Wheel Printer and Line
Printers are examples of Impact Printers and
Inkjet Printers and Laser Printers are examples
of Non-Impact Printers.

34. • Dot Matrix Printer: Each character
printed is in form of pattern of Dot's which
comes out to form a character that is why
it is called Dot Matrix Printer.
• Dot Matrix Printer is impact type printer.
• The printers that print the characters by
striking against the ribbon and onto the
paper are called impact printers.
•

36. • Line Printers: Line printers are printers
which print one line at a time.
• It is impact type printer. Two types of line
printers are: drum printer and chain
printer.
• Drum Printer: This printer is like a drum in
shape so it called drum printer.
• One rotation of drum prints one line.
• Drum Printers are fast in speed and speed
in between 300 to 2000 lines per minute.

39. • Chain Printer: In this printer chain of
character sets are used so it called Chain
Printers. A standard character set may
have 48, 64, 96 characters.

40. • Non-impact Printers: The printers that
print the characters without striking
against the ribbon and onto the paper are
called Non-impact Printers.
• These printers print a complete page at a
time, also called as Page Printers.
• These printers are of two types: Laser
Printers and Inkjet Printers.

41. • Inkjet Printers: Inkjet printers are non-impact
character printers based on a relatively new
technology.
• They print characters by spraying small drops
of ink onto paper.
• Inkjet printers produce high quality output
with presentable features.
• They make less noise because no
hammering is done and these have many
styles of printing modes available. Colour
printing is also possible.
• It is expensive as cost per page is high and
slow as compare to laser printer.

43. • Laser Printers: These are non-impact
page printers.
• They use laser lights to produces the dots
needed to form the characters to be
printed on a page.
• It gives very high quality print output.
• It is expensive.
Its printing speed ranges from 12 to 20 pages
per minute.

45. • Plotters: Plotters are ideal output device
for architects, engineers, city planners, to
generate high precision, hard copy,
graphic output of varying sizes.

46. • Speaker: It is an output device which
allow user to listen to voice like music,
even conversation with people.

47. • Screen Image Projector: Screen image
projector is an output device which is used
to project information from a computer on to
a large screen (such as a cloth screen or a
wall), so that it can be simultaneously
viewed by a large group of people.
• This output device is very useful for making
presentations to a group of people with the
direct use of a computer.
• Like monitors, screen image projectors
provide a temporary, soft-copy output.