3
Hardware Basics:
Peripherals
Chapter Outline
• Input: From Person to
Processor
“We swim
in a sea of
• Output: From Pulses to People
information.”
• Storage Devices: Input meets
Gary Snyder
Output
• Computer Systems: The Sum
of Its Parts
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3.2
The Omnipresent Keyboard
Keyboards are used to input and
manipulate information with keys
such as Letters and Numbers…
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3.3
The Omnipresent Keyboard
…Function Keys that send
special commands…
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…and Cursor Keys that
allow you to move
around the screen
3.4
Reading Tools
• Optical-mark readers
• Bar-code readers
• Magnetic-ink character
readers
• Wand readers
• Pen scanners
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3.5
Digitizing the Real World
Audio digitizing and
Speech recognition software
Sensing devices
Video digitizing
Scanners
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3.6
Scanners
Scanners capture
and digitize
images from
external paper
sources
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3.7
Video Digitizers
Video digitizers contain
circuitry to digitize
frames from camcorders
and other video sources.
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3.8
Digital Cameras
Digital cameras turn real-world
scenes into digital images that
can be stored and manipulated
by the computer
The images, stored in memory,
can be transferred to a computer
for either editing or storage
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3.9
Audio Digitizers
• Audio digitizers
contain circuitry to
digitize sounds from
microphones and
other audio devices.
• Spoken words, music,
and sound effects can
be captured.
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3.10
Output: From Pulses to People
Paper
Video Monitor
Sound
Controlling
Other Machines
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3.11
Screen Output
• Video Monitor
– Also called Video Display Terminal
(VDT)
– Image exists in video memory—VRAM
– Monitor size is measured diagonally
across the screen
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3.12
Pixels
• Images are made up of
dots called pixels for
picture elements
• The number of pixels
affects the resolution
of the monitor
• The higher the resolution,
the better the image quality
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3.13
Color Depth (Pixel Depth)
• The amount of information per pixel is
known as the color depth
– Monochrome (1 bit of information per pixel)
– Gray-scale (8 bits of information per pixel)
– Color (8 or 16 bits of information per pixel)
– True color (24 or 32 bits of information per
pixel)
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3.14
Examples of Color Depth
1-bit depth
4-bit depth
8-bit depth
16-bit depth
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3.15
Classes of Monitors
CRT (cathode ray tube)
LCD (liquid crystal display)
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3.16
CRT (Cathode Ray Tube)
A CRT is a television-style monitor
featuring:
– Clear image
– Quick response
time
– Low cost
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3.17
LCD (Liquid Crystal Display)
• LCDs are flat-panel monitors
• Features include:
– Lighter weight
– More compact
• More expensive
• Dominate the portable computer
market
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3.18
Paper Output
• Paper output is
sometimes called
hard copy
• Hard copy can come
from one of two
kinds of printers:
– Impact printers
– Nonimpact printers
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3.19
Impact Printers
• Line printers
– Used by mainframes for
massive jobs
– Limited characters available
• Dot-matrix printers
– Image formed from dots printed on paper
– Good for text and graphics
– Inexpensive
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3.20
Nonimpact Printers
• Laser printers
– Image transferred to paper
with laser beam
– Faster and more expensive
than dot-matrix
– High-resolution hard copy
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3.21
Other Nonimpact Printers
• Ink-jet
– Dots of ink are sprayed onto the paper
to form the image
– High-resolution hard copy
– Some models print can print color
photographs
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3.22
Rules of Thumb:
Ergonomics and Health
• Choose equipment that’s
ergonomically designed
• Create a healthy workspace
• Build flexibility into your work
environment
• Rest your eyes
• Stretch tight muscles
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3.23
Output You Can Hear
• Synthesizers can be
used to generate
music and sounds
• Many computers
have synthesizers
• Sound cards have
built-in synthesizers
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3.24
Controlling
Other Machines
• Output devices turn
bit patterns into nondigital movements
Robot arms
— Telephone switchboards
— Transportation devices
— Automated factory
equipment
— Spacecraft
—
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3.25
Storage Devices:
Input Meets Output
• Peripherals with both input and
output functions provide semipermanent storage for data
• Examples include:
– Magnetic tape and disks
– Zip, Jaz and SuperDisks
– Magneto-optical disks
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3.26
Optical Disks
• Optical disks use laser beams rather than
magnets to read and write information
• CD-ROM drives are optical drives that
read CD-ROMs
• CD-RW drives can write, erase, and
rewrite CDs
• DVD’s can hold between 3.8 and 17
gigabytes of data, they are replacing CDROMs
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3.27
Alternatives
• Flash memory
– Compact alternative
– No moving parts
– May eventually replace
disk and tape storage
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3.28
Ports and Slots…again
• The system board (motherboard)
includes several ports:
– Serial Port for attaching devices that
send/receive messages one bit at a time
(modems)
– Parallel Port for attaching devices that
send/receive bits in groups (printers)
– Keyboard/Mouse Port
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3.29
Ports and Slots…again
• Other ports that are generally included on
expansion boards instead of the system board:
– Video Port used to plug in a color monitor
into the video board
– Microphone, speaker, headphone, MIDI
ports used to attach sound equipment
– SCSI port allows several peripherals to be
strung together and attached to a single
port
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3.30
Internal and External Drives
• Hard drive
• CD or DVD
• Floppy disk
• Zip Drive
• SCSI port
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3.31
Expansion Made Easy
• USB and Firewire ports allow multiple devices
to be connected to the same port and to be hot
swapped:
– USB (Universal Serial Bus) transmits a
hundred times faster than a PC serial port
– Firewire (IEEE 1394) can move data between
devices at 400 or more megabits per second
 2001 Prentice Hall
3.32
Putting It All Together:
Networks
• Networks blur the boundaries
between computers
– Networks can include hundreds of
different computers
– Can span the globe by using satellites
and fiber optic cables
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3.33