An input device sends information to a computer system for processing, and an output device reproduces or displays the results of that processing. Depending on the interaction, a device can be both, referred to as an input/output or I/O device. For example, as you can see in the top half of the image, a keyboard sends electrical signals, which are received by the computer (input). Those signals are then interpreted by the computer and displayed on the monitor as text (output). In the lower half of the image, the computer sends data to a printer, which will print the data onto a piece of paper (output). An input device can send data to another device, but it cannot receive data from another device. Examples of an input device include a computer keyboard and mouse, which can send data (input) to the computer, but they cannot receive or reproduce information (output) from the computer. An output device can receive data from another device, but it cannot send data to another device. Examples of an output device include a computer monitor, projector, and speakers, which can receive data (output) from the computer, but they cannot send information (input) to the computer.

1. Input and Output Devices
Aamir Saleem Ansari
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2. What is Output?
• What is output?
 Data that has been processed into a useful form
 Output device is any hardware component that can convey
information to one or more people

3. Display Devices
• What is a display device?
 Output device that visually conveys text,
graphics, and video information
 Information on display device sometimes
called soft copy
 Monitor houses display device that is packaged
as separate peripheral

4. Display Devices
• What is an LCD monitor?
 Uses liquid crystal display
 Have a small footprint
 Mobile devices that contain
LCD displays include
 Notebook computer, Tablet
PC, ultra personal
computer, portable media
player, smart phone, and
PDA

5. Flat-Panel Displays
• What are some mobile devices that have LCD screens?

6. Flat-Panel Displays
• What is resolution?
 Sharpness and
clarity of image
 Higher resolution
makes image
sharper, displays
more text on screen,
makes some elements
smaller
 Number of horizontal
and vertical pixels in
a display device

7. Flat-Panel Displays
•How do you use an LCD monitor with a video
card?
 Plug monitor into Digital Video Interface (DVI) port
on computer
standard monitor
port
S-video port
DVI port

8. Flat-Panel Displays
• What is a plasma monitor?
 Displays image by applying voltage to layer of gas
 Larger screen size and richer colors than LCD, but are more
expensive

9. CRT Monitors
• What is a CRT
monitor? Contains cathode-ray
tube (CRT)
 Screen coated with tiny
dots of phosphor material
 Each dot consists of a red,
blue, and green phosphor
 Common sizes are 15, 17,
19, 21, and 22 inches
 Viewable size is diagonal
measurement of actual
viewing area

10. CRT Monitors
• What determines the quality of a CRT
monitor? Screen resolution
 Refresh rate is speed at which monitor redraws
images on screen
 Text created with a smaller dot pitch is easier
to read

11. Printers
• What is a printer?
 Output device that
produces text and
graphics on a physical
medium
 Result is hard copy, or
printout
 Two orientations: portrait
and landscape
portrait
landscape

12. Speed
Printers
• How do you know which printer to buy?
Budget
Color or
black and white
Cost per page
Paper types
and sizes
Graphics and
photo printing
Multiple copies
System
compatibility
 Depends on printing needs
Wireless
capability
Future needs

13. Printers
• What are the various ways to print
documents and pictures?

14. Printers
• What is a nonimpact printer?
 Forms characters and graphics without striking paper
 Ink-jet printer sprays tiny drops of liquid ink
onto paper
 Prints in black-and-white or color on a variety
of paper types

15. Printers
• What is the resolution of a printer?
 Sharpness and clarity
 Measured by number of dots per inch (dpi) printer
can output

16. Printers
• How does an ink-jet printer work?
Step 1. A small
resistor heats the
ink, causing the
ink to boil and
form a vapor
bubble.
Step 2. The
vapor bubble
forces the ink
through the
nozzle.
Step 3. Ink
drops onto the
paper.
Step 4. As the vapor bubble
collapses, fresh ink is drawn into
the firing chamber.
print cartridge
print head
firing
chamber
nozzle
bubble resistor ink
ink dot

17. Printers
• What is a photo printer?
 Color printer that produces
photo-lab-quality pictures
 Many photo printers have a
built-in card slot
 PictBridge is a standard
technology that allows you to
print pictures directly from a
digital camera

18. Printers
• What is a laser printer?
 High-speed, high-quality
nonimpact printer
 Prints text and graphics in
high-quality resolution,
ranging from 1,200 to 2,400 dpi
 Typically costs more than
ink-jet printer, but is much
faster

19. Printers
• How does a laser printer work?

20. Printers
• What are label printers and postage
printers?
 Small printer that prints on adhesive-type material
 Postage printer has built-in
 digital scale and prints
postage stamps
 Most also print bar codes

21. Printers
• What is a plotter?
 Sophisticated printer used to produce high-quality
drawings
 Large-format printer creates photo-realistic-quality
color prints

22. Printers
• What is a dot-matrix printer?
 Impact printer that produces printed images
when tiny wire pins strike ribbon
 Impact printer forms
characters by striking
mechanism against inked
ribbon that contacts paper

23. Printers
• What is a line printer?
 High-speed impact printer
that prints entire line
at a time
 Speed measured in lines
per minute (lpm)
 Band printer prints fully
formed characters using a
hammer mechanism
 Shuttle-matrix printer is
high-speed printer that
works like dot-matrix
printer

24. Speakers, Headphones, and Headsets
• What is an audio output device?
 Computer component that produces music, speech, or
other sounds
 Speakers and headsets are common devices

25. Other Output Devices
• What is a facsimile (fax) machine?
 Device that transmits and receives documents over
telephone lines

26. Other Output Devices
• What is a fax modem?
 Modem that allows you to send and receive electronic
documents as faxes
external fax
modem
internal fax card
in system unit
fax machine

27. Other Output Devices
• What is a multifunction peripheral?
 Provides functionality
of printer, scanner,
copy machine, and
fax machine

28. Any Questions and for
more details
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