Hardware devices that are used to input and output data to a computer are called I/O devices. Input devices capture information from the external environment and convert it into a format that can be processed by the computer. Examples include keyboards, mice, scanners, microphones, and webcams. Output devices take the processed data from the computer and present it to the user. Common output devices are monitors, printers, speakers and plotters. Monitors display soft copy output while printers provide hard copy printouts.

1. Hardware
Input/Output (I/O) Devices
Instructor : Muhammad Hammad Waseem
Email: m.hammad.wasim@gmail.com
Course : Introduction to Computer
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2. Hardware
 Hardware is a comprehensive term for all of the
physical parts of a computer.
 All the input and output devices of the computer lies in
hardware.
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3. Input Devices
 Input device captures information and translates it
into a form that can be processed and used by other
parts of your computer.
 In computing, an input device is any peripheral (piece
of computer hardware) used to provide data and
control signals to a computer or
other Systems.(Wikipedia)
 The computer follows the instructions given to it by an input
device.
 A variety of input devices are used with the computer
depending on the type and purpose of input information.
 For example, a keyboard is commonly used to transfer data
or information from human readable form to machine
readable form.
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4. Examples of Input Devices
 Keyboards
 Pointing devices
 Scanners
 Game controllers
 Microphones
 Digital cameras
 Webcams
 Styluses
 Barcode reader
etc
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5. Keyboard
 A keyboard is the most commonly used input device which
helps us in simply keying in required information in a
computer.
 A keyboard can be used effectively to communicate with the
computer but considered to be relatively slow as compared to
other input devices.
 The keyboard is divided into following divisions:
 ALPHABETIC KEYPAD
 These keys are similar to a standard typewriter and is used
to type general information.
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6. Keyboard (cont.…)
 NUMBERIC KEYPAD
 These keys are used to input numeric data only. These are
very useful in case of large numeric data input because all
numeric keys can be accessed by one hand only. These
keys can also be used as an alternative to the screen
navigation and editing keys.
 FUNCTION KEYS
 These are keys marked as F1 - F12, located normally at
the top of the keyboard.
 Each of these function keys are given some special
function in different packages.
 SCREEN NAVIGATION AND EDITING KEYS
 These keys are provided to move around in the screen. May
programs use these keys to let the user move around the screen
display. In some keyboards these keys are also provided inside
the numeric keypad as alternate keys.
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7. Parts of Keyboard 7
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8. Mouse
 The mouse is an input device that usually contains one or
two buttons.
 The mouse is used to control the on-screen pointer by
pointing and clicking, double-clicking, or dragging objects on
the screen.
 As a user moves the mouse on a flat surface, the mouse
controls the cursor movement on the screen.
 When the user presses one of the buttons, the mouse either
marks a place on the screen or makes selection from data or
menu on the screen.
 A mouse can be used for many application, ranging from
games to drawing and designing products with computer
graphics.
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9. Scanner
 Scanner is an input device. It is also called Optical Reader
or Digital Scanner.
 Scanner scans or reads text and picture printed on a
paper and enters them directly into the computer
memory.
 The advantage of a scanner is that the user needs not type
the input data in.
 The scanner takes electronic images, of text or pictures from
the paper and stores them into the computer.
 Optical Character Recognition (OCR) software translates the
scanned document into text that can be edited.
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10. Game Controllers
 Game controllers are used mainly to play games
 Types of gaming devices
 Gamepads
 Joysticks
 Gaming wheels
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11. Microphone
 Microphone allows the user to record sounds as input to
their computer.
 Speech recognition is increasingly being included in
application software therefore the use of microphone is also
increased.
 Microphone can be used individually and also used with the
headphone.
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12. Digital Cameras
 Digital cameras are used to:
 Download images to a computer
 Post pictures to the Web
 Produce videos
 Resolution is measured in megapixels/
 Higher the resolution, better the image quality, but the more
expensive the camera.
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13. Web Cam
 Web cam is a video camera that can be used to take images
for uploading to the Web.
 A webcam is a video camera that feeds its images in
real time to a computer. (Wikipedia)
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14. Stylus
 A Stylus is an input device consisting of a thin stick that uses
pressure to enter information or to click and point.
 Styluses are used with:
 PDAs
 Tablet PCs
 Graphics tablets
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15. Barcode Reader
 An input device that converts a pattern of printed bars into a
number that a computer can read.
 They are often used by businesses to quickly input price and
product information.
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16. Question Answer Session….
1. Most commonly used input device is___?
2. The keyboard is divided into ___ divisions?
3. Pointing device which we have studied so far?
4. Scanner is an ___device. It is also called___?
5. Which software translates the scanned document
into text?
6. Types of gaming devices?
7. Resolution is measured in ___?
8. Web cam is used for?
9. What is stylus?
10. What is barcode?
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17. Output Devices
 Output Devices take information within your
computer and present it to you in a form that you can
understand.
OR
 The devices which are used to display the data to the
user either in the form of hard copy or soft copy are
called Output Devices.
OR
 An Output Device is any piece of computer
hardware equipment used to communicate the results
of data processing carried out by an information
processing system (such as a computer) (Wikipedia)
 The output devices gives us output in two form
 Hardcopy
 Softcopy
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18. Output Devices (Cont.…)
Hard Copy:
 Hard Copy is a permanent copy, in the form of a
physical object.
 Like print out on the paper.
Soft Copy:
 A Soft Copy is an electronic copy of some type of data,
such as a file viewed on a computer's display (Screen).
 Examples of Output Devices are:
 Monitors
 Printers
 Speakers
 Plotters
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19. Monitors (Computer Display)
 To display result or output from computer, a T.V like device is
used which is called monitor.
 The monitors are also referred as C.R.T (Cathode Ray
Tube), V.D.U (Visual Display Unit).
 The monitor assist during input from the keyboard, this
display is called a soft copy.
 The monitor can be of various kinds, depending on the type
of application.
 Monitors are categorized into two groups:
 Monochrome monitors
 Color monitors
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20. Monitors (Cont.…)
Monochrome Monitor
 A monochrome monitor has two colors, one for foreground
and the other for background. The colors can be white,
amber or green on a dark (black) background.
 The monochrome monitors display both text and graphics
modes.
Color Monitors
 Color monitors implement the RGB color model by using
three different phosphors that appear Red, Green, and Blue
when activated.
 A color monitor displays more than two colors. Color monitors
have been developed through the following paths.
 Enhance Graphic Array (EGA),
 Colour Graphic Array (CGA),
 Video Graphics Array (VGA),
 Super Video Graphics Array (SVGA).
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21. Forms of Monitor
 There are two forms of monitor:
 Cathode-Ray Tubes (CRTs)
 Flat-panel Display.
Cathode Ray Tubes (CRT)
 The CRT monitors are a lot like television set,
using the same CRT or Cathode Ray Tube technology.
 The CRT monitor has two major parts;
 the screen and
 the cathode ray tube (CRT).
 The screen is the front of the monitor and
CRT is fitted inside the monitor.
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22. Forms of Monitor (Cont.…)
Flat Panel Displays
 Portable computers such as a laptop use flat panel displays,
because they are more compact and consume less power
than CRTs.
 Portable computers use several kinds of flat panel screens:
 Liquid-Crystal Displays (LCDs)
 Electroluminescent (EL) Displays
 Gas Plasma Displays
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23. Forms of Monitor (Cont.…)
Liquid-Crystal Displays (LCDs)
 A display technology that creates characters by means of
reflected light and is commonly used in digital watches and
laptop computers.
 LCDs replaced LEDs (light emitting diodes) because LCDs
are difficult to read in a strong light, because they do not emit
their own light.
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24. Forms of Monitor (Cont.…)
Electroluminescent (EL) Displays
 A flat panel display technology that actively emits light at
each pixel when it is electronic charged.
 This provides a sharp, clear image and wide viewing angle.
 The EL display type of flat panel is better than LCD.
Gas Plasma Displays
 This is also called a gas panel or a plasma panel and is
another flat screen technology.
 A plasma panel contains a grid of electrodes in a flat, gas
filled panel.
 The image can persist for a long time without refreshing in
this panel.
 The disadvantages of the gas plasma displays are that they
must use AC power and cannot show sharp contrast.
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25. Printers
 A printer is an output device that produces a hard copy of
data. The resolution of printer output is expressed as DPI.
 Printer can be categorized in several ways the most common
distinction is
 Impact and
 Non-Impact.
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26. IMPACT PRINTING NON – IMPACT PRINTING
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Printers
 Is the method used by the
conventional type writers.
 In some type of impact
printing a metal “hammer”
embossed with a character
strikes a print ribbon, which
presses the characters
image into paper.
 No physical contact at all
occurs between the printing
mechanism and the paper.
The most popular non-
impact methods today
utilize thermal transfer, ink-
jet.
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27. Types of Printers
Dot Matrix Printer
 Dot-matrix printers are printers that write characters and
form graphic images using one or two columns of tiny dots on
a print head.
 The dot hammer moving serially across the paper strikes an
inked-ribbon and creates images on paper.
 The quality of output from a dot matrix printer depends
largely on the number of dots in the matrix.
 Dot matrix printers are often categorized by the number of
pins in the printer head typically, 9 or 24. Several kinds of dot
matrix printers are available with print heads that have 7, 9,
18, or 24 pins.
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28. Types of Printers (Cont.…)
Daisy-Wheel Printer
 Daisy wheel printer are some times called letter quality
printer because they are often used to produce attractive
correspondence.
 The D.W.P is a flat circular device made of metal with
character embossed on it. As this wheel spins at a very high
speed the hammer hits the specific character against the
ribbon which presses against the paper.
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29. Types of Printers (Cont.…)
Line Printers
 Any printer that prints one line at one time, as opposed to
one character at a time or one page at a time.
 They are high speed devices and are often used with
mainframes, minicomputers, or networked machines rather
than with single user system.
 Types of line printers include
 chain printers.
 band printer.
 Line printers are very reliable and can
speed up to 3000 lines per minute (LPM).
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30. Types of Printers (Cont.…)
Ink-Jet Printer
 Ink-jet is a printer mechanism that sprays one or more color
of ink at high speed onto the paper and produces high-quality
printing.
 This printer also produces color printing as well as high-
quality image.
 Ink-jet printers can be used for variety of color printing at a
relatively low cost.
 Ink-jet printing has two methods:
 Continuous stream method
 Drop-on- demand method.
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31. Types of Printers (Cont.…)
Laser Printers
 An electrophotographic printer that is
based on the technology used by
photocopiers.
 Laser printer resolution is typically
from 300 to 1200 dpi, but specialty
printers can reach imagesetter
resolution of 2400 dpi.
 Low-end laser printers print in the 4
to 8 ppm range, while typical office
workgroup units print 17 to 32 ppm.
 Midrange units print in the 40-60
ppm range.
 High-end printers that print from 150
to more than 1,000 ppm.
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Working of Laser Printer
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32. Speakers
 A device containing a transducer that converts
electrical signals (electric current) into sound waves
(acoustic energy) for the production of sound.
 This device produces a human speech like sound, but
actually is prerecorded vocalized sounds.
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33. Plotter
 Plotter is a special output device, which is used to produce
high quality, perfectly proportional hard copy output.
 Plotters are designed to produce large drawings or images
such as construction plans for buildings or blue prints for
mechanical devices.
 A plotter is composed of a pen, a move-able carriage, a drum
and a holder for chart paper.
 Both the pen and the paper can move up and down and back
and forth. This permits very detailed drawings.
 There are two types of plotters, which are as follows:
 Drum Plotter
 Flatbed Plotter
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34. Plotter (Cont.…)
DRUM PLOTTER
 On the drum plotter, the pens, and the drum move
concurrently in different axes to produce the image.
 Drum plotters are used to produce continuous output, such
as plotting earthquake activity, or for long graphic output,
such as structural view of a skyscraper.
FLATBED PLOTTER
 On some flatbed plotters, the pen moves in both axes while
the paper remains stationary.
 However, on most desktop plotters, both paper and pen
move concurrently in much the same way as on drum
plotters.
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35. 35
Plotter (Cont.…)
Drum Plotter
Flatbed Plotter
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36. Question Answer Session….
1. Define output devices.
2. What is diff. b/w hard and softcopy?
3. Name Forms of monitor?
4. RGB stands for?
5. Define monochrome monitor.
6. CRT & LCD stands for?
7. Printers are categories into__ divisions?
8. How many no. of pins are used in Dot matrix
printers?
9. What is the Speed of Line printers in (LPM)?
10. There are two types of plotters, which are?
11. Diff. b/w drum & flatbed plotters.
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