UNIT 4: Information Input and
Output
Input/ Output Devices and Storage
Objectives
Understand common input devices
Understand common output devices
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Why are Peripheral devices important
to you!
Understanding what input/output devices are
available will enable you to take full advantage
of your computer
Learning about input/output devices can help
you make informed decisions related to
ergonomic purchases
Using certain input/output devices can help you
to be more productive at work and in your
personal life
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Information Input and Output
Input and Output Devices
Input device converts our
commands and data into a form a
computer can understand
Output device converts computer
data into a form humans can
understand
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Information Input and Output
The Keyboard
Traditional alphanumeric keyboard
QWERTY
Special-function keyboard
Fast-food cash registers
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Information Input and Output
The Mouse
Used in a GUI (Graphical User
Interface)
Point and select (click)
Mouse pointer cursor
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Information Input and Output
Other Pointing Devices
Trackpad
Used mostly on notebook computers
Move your finger over the touch-sensitive pad
Trackpoint similar to a miniature joystick
Trackball similar to an upside-down
mouse
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Information Input and Output
Other Pointing Devices
Joystick vertical stick used to move
the pointer
Digitizer tablet and pen allow for
the digitizing of images
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Additional Point-and-Draw Devices
Joystick
Trackball
Digitizer Tablet
and Pen
Trackpad
Trackpoint
Photos Courtesy of:
Imation Corporation
Houston Instrument Div. AMETEK, Inc.
Advanced Gravis Computer Technology Ltd.
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Information Input and Output
Scanners
Scanners convert printed matter into
a format that can be stored in a
computer
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Information Input and Output
Scanners for Source Data Automation
Handheld label scanner or wand
scanner
Stationary label scanner
Document scanner
Turnaround document
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Information Input and Output
Bar Code
UPC Universal Product Code
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Information Input and Output
OCR Technology
OCR (optical character recognition)
scans characters into a computer
MICR (magnetic-ink character
recognition) used in banking
industry
OMR (optical mark recognition)
used to grade tests or questionnaires
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OCR and Bar Code Scanners
Optical character
recognition (OCR)
Reads coded
information and text
Types
Contact and Laser
Handheld
Label
Document
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Optical Mark Recognition
Grades test
Checks survey
The sense marks are
compared on the test
by the scanner
Corrections are
calculated
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Information Input and Output
Image Scanners
Image scanner capable of
translating text or images into a form
a computer can read
Image processing manipulating
scanned images
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Information Input and Output
Page and Hand Image Scanners
Page image scanner works like a
copy machine
Hand image scanner manually
rolled over the image to be scanned
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Information Input and Output
Magnetic Stripes
Magnetic stripes like the ones on
credit cards
Badge reader device to read an
employees badge to determine
clearance
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Information Input and Output
Smart Card
Can store information or money
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Magnetic Stripes and Smart
Cards
Magnetic stripes on the
back of bank cards and
ID badges are encoded
with data
When they are swiped
the device reads the card
Smart cards look like a
regular bank card, but
contain 32 KB of memory
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Pattern Recognition
Uses a camera to digitize
the image
Stores digitized image in
a database
Continually compares
new images to stored
images in database
Suited to very specialized
tasks like quality-control
inspections
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Information Input and Output
Speech Recognition
Speaker-dependent can interpret
spoken words from only one person
Speaker-independent will accept
words from anyone, but has a limited
vocabulary
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Information Input and Output
Digicams
Digital camera records images
digitally
Digital video camera captures
motion video
Webcams digital video cameras
connected to the Internet
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Information Input and Output
Digicams
Digital camcorder captures video
digitally
Video capture card expansion card
that allows for the capture of video to
disk
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Information Input and Output
Handheld and Wearable Data Entry
Devices
Limited keyboard
Small touch-sensitive display
Storage capability probably solidstate
Scanning device capable of OCR
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Handheld and Wearable Data Entry Devices
Actually a small computer
which includes:
Limited external keyboard
or soft keyboard
Small display (touch
sensitive)
Storage capacity (flash
memory)
Scanning device for OCR
Capture data and upload
to a central computer
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Touch Screen Monitors
Touch screen
monitors have
pressure-sensitive
overlays that detects
pressure
Users touch the icon
or menu item to make
their selections
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Output
Monitors
Projectors
Printers
Speakers
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Monitors
CRT monitors
Excellent resolution
Larger size
Flat-panel monitor
Found on all
notebooks
More expensive
Takes up less space
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Information Input and Output
Flat-Panel Monitors
LCD (liquid crystal display)
Active matrix more brilliant display,
also called TFT (thin film transistor)
Passive matrix
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LCDs
Most LCD displays use active matrix technology = more
brilliant display, also called TFT (thin film transistor)
An LCD is made of two pieces of polarized glass (also
called substrate) that contain a liquid crystal material
between them. A backlight creates light that passes
through the first substrate. At the same time, electrical
currents cause the liquid crystal molecules to align to
allow varying levels of light to pass through to the second
substrate and create the colors and images that you see.
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LCDs
The signal comes in and, as with a CRT, the
signal from the video controller is decoded and
understood by a display controller on the monitor
itself. The controller has two things to control the electrics of the pixels and the light source.
The actual image on a TFT is made up of a
matrix of pixels.
Unlike with CRTs, there's no complex equation of
dot pitch and image area to try and calculate
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LCDs
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CRTs
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CRTs
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CRTs
CRTs receive their picture through an analogue cable, and
that signal is decoded by the display controller, which
handles the internal components of the monitor - think of it
as the mini-CPU for the monitor.
CRTs have a distinctive funnel shape. At the very back of
a monitor is an electron gun. The electron gun fires
electrons towards the front through a vacuum which exists
in the tube of the monitor.
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Projectors
Use DLP Digital Light Processing
Array of mirrors
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Information Input and Output
Monitors
Graphics adapter monitors device
controller
Video Ram or VRAM memory on
the graphics adapter where images are
prepared for display on the monitor
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Information Input and Output
Monitors
Dual monitor high-end graphics
adapters, allow for multiple monitors
to be connected to one PC
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Information Input and Output
Monitors
Touch screen monitor user indicates
choice by touching the screen
LCD projector allows the user to
project what is on the computer
monitor onto a large screen for an
audience
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Graphics Adapters
Device controller for the monitor
Inserted into expansion slot
Most graphics adapters have their own
video RAM (VRAM)
Size of video RAM is important
VRAM determines the number of possible
colors and the resolution of the display
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Monitor Size
Measured diagonally
5 to 60 inches
15 inch
17 inch
19 inch
21 inch
The bigger the more
costs
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Information Input and Output
Monitor Resolution
Pixel (picture element) a dot on the
screen
Gray scales number of shades of a
color that can be displayed
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Monitor Resolution
1024 pixels
768
pixels
Students are great!
The size of the screen image
is measured in pixels.
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Monitor Resolution Bits Used
Grayscale
RGB monitors
Color depth
8-bit
(246 colors)
16-bit (high color, 65,536
colors)
24-bit or 32-bit (true color,
>16 million colors)
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Monitor Resolution-Dot Pitch
The distance between centers of adjacent pixels.
Low Resolution
Higher Resolution
.28mm (millimeters) or less is recommended
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Refresh Rate
The number of times
per second the
screen image is
redrawn
Faster refresh rates
have fewer flickers
and is easier on the
eyes
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CRTs vs. LCDs (Summary)
Advantages/Disadvantages of LCD /Flat Panel
Monitors
Require less power & LCDs also produce less heat.
Smaller and weigh less - takes up less desktop
space.
More adjustable.
Less eye strain - Because LCD displays turn each
pixel off individually
resolution not as clear as a CRT monitor
lightweight and portable
more expensive
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CRTs vs. LCDs (Summary)
Advantages/Disadvantages of CRT
Monitors
Less expensive - competitive price
Better color representation
More responsive - faster response times
Multiple and excellent resolutions
More rugged
Take up a lot of space in a work area and
are bigger and heavier
Produces more heat, requires more power
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LCD Projectors
Presentation graphics
Multimedia projectors
LCD panels
LCD projectors
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Information Input and Output
Printers
Printers produce hardcopy such as term
papers, reports, labels,
and more
Considerations:
Budget
Black/white or color
Volume
Quality
Special needs
Network considerations
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Information Input and Output
Printers
Laser printer prints a page at a time
Ink-jet printer ink is sprayed onto
paper to form characters and images
Large-format ink-jet printer used to
create large documents such as
blueprints
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Considerations when buying a printer:
Printers produce hard copy output.
What is the budget?
Is color needed or will black and white do?
What will the volume of output be (pages per hour,
day, or week)?
How important is the quality of the output?
What special features are needed (ability to print
envelopes, on legal size paper, on multipart forms, on
both sides of the paper, and so on)?
Can printing needs be met with an all-in-one device?
(printer/copier/scanner/fax)
If the printer is to be shared on a network, what do the
other users want?
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Printers
Laser printer prints a page at a time
Ink-jet printer ink is sprayed onto paper
to form characters and images
Large-format ink-jet printer used to
create large documents such as blueprints
All-in-one multifunction device has all
of the capabilities of a printer, fax
machine, scanner, and copier
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Page Printers
Nonimpact
Laser, LED, LCS
High speed 4-32 ppm
Near-typeset-quality
600 dpi to 1200 dpi
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Ink-Jet Printers
Nonimpact
Budget-minded
consumers choice
1200 dpi for
black/white
4800 dpi for color
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Inkjet Printer For e.g. HP Inkjet
Ink not bonded to paper. Microscopic jet of Ink
squirted/sprayed unto paper
ink blots with contact with liquids
There is no head the head to write/print data is
located in the ink cartridge
Expensive ink higher maintenance/operating cost
when cartridges must be replaced often with regular
use
Every a couple hundred pages at best, the cartridge
needs to be replaced with a new one = more
expensive per page.
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Inkjet Printer
Individual color mixing tanks/cartridges
pictures printed better than laser and may
be cheaper when different colors depleted.
Cheap print and poor quality
Good for domestic or personal use, and
intermittent printing ; on-and-off printing
Lower initial purchase cost for printer
slow speed (up to 20 ppm) and variable
print quality
Smaller footprint and waste
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Laser Printer- For e.g. Canon laser
Use electrostatics and a laser beam- Laser uses a constant
laser which is a positively charged ion, and a mirror.
Permanently fixed head in the body of the laser printer
Holes in the print head tend to clog if printer is not used
frequently
Cheaper toner compared to ink cartridge cheaper
operating cost; Higher toner capacity over time which lowers
total cost per page.
Ink is sprayed then burnt/bonded to paper
Ink doesnt blot when paper comes into contact with liquids
Uses toner cancer causing if ink makes contact with skin
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Other Printers
Dot-matrix
Prints one character at
a time
All-in-one
multifunction device
Print
Fax
Scan
Copy
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Information Input and Output
Sound
Sound card
Speaker system,
Headphones
Integrated or adapter audio card
amplifier
I/O of audio signals
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Information Input and Output
Voice Output
Voice Response System
Reproduction of a human voice
Speech synthesis
Speech synthesis system converts
data into electronic speech
Text-to-speech software produces
speech by combining phenomes
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Device Drivers - importance
Technology for the Disabled
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