Using Information Technology
Chapter 5
Hardware--Input & Output
Hardware--Input & Output
Taking Charge of Computing &
Communications
5.1 Input & Output
5.2 Input Hardware
5.3 Output Hardware
5.1 Input & Output
• Input hardware devices that
translate data into a
form the computer
can process
• Output hardware devices that
translate
information
processed by the
computer into a
form that humans
can understand
5.2 Input Hardware
• Keyboard - a device that
converts letters,
numbers, and other
characters into electrical
signals that can be read
by the computer’s
processor
Braille keyboard
• Traditional keyboards…
One-handed keyboard
Keyboards
• Specialty keyboards
and terminals:
• Dumb terminal,
VDT, display &
keyboard, but no
processing
• Intelligent terminal
• Internet terminal
Dumb terminal
Keyboards
• Specialty keyboards
and terminals:
• Dumb terminal
• Intelligent terminal
Has own memory
& processor
• Internet terminal
• Examples of intelligent
terminals:
• Automatic teller
machine (ATM)
• Point-of-sale (POS)
terminal
Keyboards
• Specialty keyboards and
terminals:
• Dumb terminal
• Intelligent terminal
• Internet terminal:
–
–
–
–
–
Web terminal
Network computer
Online game player
PC/TV
PDA
PDA (Internet terminal)
Pointing Devices
• Pointing devices control the position of
the cursor or pointer on
the screen
•
•
•
•
Mouse
Trackball
Pointing stick
Touchpad
Mouse for right-handed user
Pointing Devices
• The mouse and
its variants:
Touch pad
– Mouse
– Trackball
– Pointing
stick
– Touchpad
Ergonomic trackball
Pointing stick
Pointing Devices
• Touch screen - a video display screen that has been
sensitized to receive input from the touch of a finger
Touch screen
Pointing Devices
Pen input:
• Pen-based computer system allows users to enter
handwriting and marks onto a
computer screen by means of a
penlike stylus rather than by
typing on a keyboard
• Light pen - a light-sensitive
penlike device connected by a
wire to the computer terminal
Pointing Devices
Pen input:
• Digitizer - converts
drawings and photos
to digital data using a
mouselike device
called a puck
• Digitizing tablet electronic plastic
board on which each
specific location
corresponds to a
location on the screen
Digitizing tablet
Source Data-Entry Devices
Scanning devices imaging systems:
• Scanners - devices that
use light-sensing
equipment to translate
images of text, drawings,
photos, and the like into
digital form
Source Data-Entry Devices
Scanning devices –
bar-code readers:
• Bar codes - vertical zebrastriped marks you see on
most manufactured retail
products
• Bar-code readers - optical
scanners that translate the
symbols in the bar code into
digital code
Source Data-Entry Devices
Scanning devices - mark- & character-recognition:
•
MICR - Magnetic-ink character recognition. Reads
the strange-looking numbers printed at the bottom of
checks
•
OMR
•
OCR
Source Data-Entry Devices
Scanning devices - mark- & character-recognition:
•
•
•
MICR
OMR - Optical mark recognition. Uses a device
that reads pencil marks and converts them into
computer-usable form
OCR
Source Data-Entry Devices
Scanning devices:mark- & character-recognition:
•
MICR
•
OMR
•
OCR - Optical character recognition. Uses a
device that reads preprinted characters in a
particular font and converts them to digital code
Source Data-Entry Devices
• Scanning devices fax machines…
• Types of fax
machines:
• Dedicated fax
machine
Dedicated fax machine
• Fax modem
Fax modem
Other Source Data-Entry Devices
• Audio-input devices
• Webcams and videoinput cards
• Digital cameras
• Voice-recognition
systems
Other Source Data-Entry Devices
• Audio-input devices
• Webcams and video-input
cards
• Digital cameras
• Voice-recognition systems
• Human-biology input
devices (biometrics)
5.3 Output Hardware
•Softcopy - data that is shown on a display
screen or is in audio or voice form
•Hardcopy - printed output
Softcopy Output: Display Screens
• Display screens - output devices that show
programming instructions and data as they are being
input and information after it is processed
Softcopy Output: Display Screens
• Screen clarity…
• Pixel (picture element) - the
smallest unit on the screen
that can be turned on and
off or made different shades
Softcopy Output: Display Screens
• Screen clarity…
• Dot pitch (dp) - the
amount of space
between the centers of
adjacent pixels; the
closer the dots, the
crisper the image
Softcopy Output: Display Screens
• Screen clarity…
• Standard resolutions
• (horizontal x vertical)
• Resolution - the image
sharpness of a display
screen; the more pixels
there are per square
inch, the finer the level
of detail
• dpi = dots per inch
•
•
•
•
•
•
640 x 480
800 x 600
1024 x 768
1280 x 1024
1600 x 1200
1920 x 1440
Softcopy Output: Display Screens
•Screen clarity…
•Refresh rate - the number of times per second that the
pixels are recharged so that their glow remains bright
•The higher the refresh rate, the more solid the image
looks (less flicker).
Softcopy Output: Display Screens
Two types of monitors:
• CRT - a vacuum tube
used as a display screen
in a computer or video
display terminal
• Flat-panel display made up of two plates
of glass separated by a
layer of a substance in
which light is
manipulated
Softcopy Output: Display Screens
Active-matrix versus passive-matrix flat-panel
displays:
– Active-matrix - each pixel on the screen is
controlled by its own transistor (brighter & sharper,
but more expensive)
– Passive-matrix - a transistor controls a whole row or
column of pixels (provides sharper image for single
color screens but more subdued for color)
Softcopy Output: Display Screens
Color & resolution standards:
• SVGA – Super video graphics array (most common w/ 15”
monitors)
• XGA – Extended graphics array (17-19” monitors)
• SXGA – Super extended graphics array (19”-21” monitors)
• UXGA - Ultra extended graphics array (popular w/ design &
graphic artists
Hardcopy Output: Printers
•Printer - an output device that prints characters,
symbols, and perhaps graphics on paper or
another hardcopy medium
•Dpi (dots per inch) - resolution measure for
printers. Specifies the number of dots that are
printed in a linear inch
Hardcopy Output: Printers
•Impact printer - forms characters or images by striking a
mechanism such as a print hammer or wheel against an inked
ribbon, leaving an image on paper (dot matrix printer)
•Non-impact printer - forms characters and images without
direct physical contact between the printing mechanism and
paper
–Laser printer - creates images on a drum which are treated with a
magnetically charged toner, & then transferred from drum to paper
–Ink-jet printers - spray small, electrically charged droplets of ink
from four nozzles through holes in a matrix at high speed onto
paper
–Thermal printers - use colored waxes and heat to produce high
quality images by burning dots onto special paper
Hardcopy Output: Printers
• Multifunction printer - output device that combines
several capabilities, such as printing, scanning,
copying, and faxing
Other Output
•Sound output - devices which produce digitized
sounds, ranging from beeps and chirps to music
•Voice output - devices which convert digital
data into speech-like sounds
•Video output - photographic images which are
played at 15-29 frames per second to give the
appearance of full motion
Concept Check
• Which type of scanning technology reads the
special characters printed at the bottom of
checks?
• Magnetic-ink character recognition (MICR)
Concept Check
• What is the smallest unit on the screen that can
be turned on and off or made different shades?
• Pixel (short for picture element)
Concept Check
• What is the measure specifying the number of
times per second that screen pixels are
recharged?
• Refresh rate
Concept Check
• How is screen resolution specified--vertical x
horizontal, or horizontal x vertical?
• Horizontal x vertical
Concept Check
• What is the measure of resolution for printers?
• Dots per inch (dpi)
Concept Check
• What is the amount of space between the
centers of adjacent pixels?
• Dot pitch (dp)
Concept Check
• What type of scanning technology is used to
read pencil marks, such as those made by
students on examination forms?
• OMR (Optical mark recognition)
Concept Check
• What is an example of an impact printer?
• Dot-matrix printer
Concept Check
• Which type of printer produces the very
highest-quality color output?
• Thermal printer
Concept Check
• What type of input device consists of a small,
flat surface over which you slide your finger,
using the same movements as you would with
a mouse?
• Touchpad
Concept Check
• What is the term for printed output?
• Hardcopy
Concept Check
• Does a very crisp image require a small dot
pitch or a large dot pitch?
• A small dot pitch (the closer the dots, the
crisper the image)