Transcript Chapter 6

Chapter 6: Input & Output
Taking Charge of Computing &
Communications
Key Questions
6.1 How is input and output hardware used by a
computer system?
6.2 What are the three categories of input
hardware, what devices do they include, and
what are their features?
6.3 What are the two categories of output
hardware, what devices do they include, and
what are their features?
6.4 What are some examples of the future of
input and output technology?
I. Input Hardware
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Keyboards
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Pointing Devices
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Source Data-Entry Devices
II. Pointing Devices
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Mice, Trackballs, & Joysticks
– Mouse
– Trackball
– Pointing stick
– Touchpad
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Light Pen
Digitizing Tablet
Pen-Based Systems
III. Common Hardware for
Source Data-Entry
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Bar-Code Readers
– Bar codes(Universal Product Code or UPC)
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Mark-Recognition & Character-Recognition
– Magnetic-ink char recognition (MICR)
• Banking industry
– Optical-mark recognition (OMR)
• Tests and examinations
– Optical-char recognition (OCR)
• Utility companies using turn-around documents
• Convert printed text to digital form
MICR technology
Checks use magnetized ink that
can be read by a bank’s magneticink character-recognition equipment.
Other Input Devices
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Scanning Devices: Imaging Systems
– Flatbed image scanners
– Sheetfed image scanners
– Handheld image scanners
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Audio-Input
Video-Input
Digital Cameras
Summary of input devices
IV. Output Hardware
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Softcopy
– data that is shown on a display
screen or is in audio or voice form
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Hardcopy
– Printed on paper, microfilm and
microfiche
V. Softcopy: Display Screens
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Cathode-Ray Tubes (CRTs)
Flat-Panel Displays
– Substances between plates
• Liquid crystal display (LCD)
• Electroluminescent (EL)
• Gas-plasma display
– Arrangements of transistors
.Active-matrix:brighter, sharper and $$$
.Passive-matrix: need less power
How a CRT works
Display Screen

Screen Clarity
– Resolution: image sharpness
• horizontal & vertical pixels: 800x600, 1024x768
– Dot pitch: space between adjacent pixels
• dot pitch < .31 millimeter provide clear images
– Refresh rate:
• how often the pixels are recharged
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Monochrome Versus Color Screens
Bitmapped Displays
Video Display Adapters
VI. Hardcopy Output
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Impact Printers
– Print char or images by striking a
mechanism (hammer) against an inked
ribbon, leaving an image on paper
– Dot Matrix Printer
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Nonimpact Printers
– Laser printer
– Ink-jet printer
– Thermal printer
Printer comparisons
Type
Technology
Advantages
Dot-matrix
IMPACT: Print
head strikes an
inked ribbon
against paper
Laser
Disadvantages
Typical
Speed
Approximate
Cost
Inexpensive; output
Noisy; low quality
char & graphics; can
print multi-part forms;
low cost per page
30 to
500+
cps*
$100-$2000
Laser beam
directed onto a
drum, “etching”
spots that attract
toner, which is
then transferred
to paper
Quiet; excellent
quality; output of text
and graphics; very
high speed
High cost,
especially for color
8-200
ppm*
$500-$20,000
Ink-jet
Electrostatically
charged drops
hit paper
Quiet; prints color,
text, and graphics;
less expensive; fast
Relatively slow;
clogged jets; fewer
dots per inch
35-400+
cps
$150-$2000
Thermal
Temperaturesensitive paper
changes color
when treated;
Quiet; high-quality
color output of text
and graphics
Special paper
required;
expensive; slow
11-80
cps
$2000$22,000
*cps = characters per second; ppm = pages per minute
In & Out
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Terminals:
– Used to access another machine
– Monitor & Keyboard
– Dumb: no local processing power
– Intelligent: CPU and RAM
– Special Purpose: Point-of-sale (POS)
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Touch Screens
Summary of output devices