Chapter 3
Hardware Basics:
Peripherals
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Chapter Outline
Input: From Person to Processor
Output: From Pulses to People
Storage Devices: Input meets Output
Computer Systems: The Sum of Its Parts
“We swim in a sea of information.”
Gary Snyder, poet
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Input: From Person to Processor
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The Keyboard
The most common input device is the keyboard,
which is used to enter letters, numbers and special
characters.
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Working with the Keyboard
• Function keys are special purpose keys whose function
depends on the software being used.
• Cursor keys are used to move the cursor up, down, left,
or right.
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Variations on Keyboard Design
Ergonomic
 to address repetitive stress injuries
Wireless
Folding
Half
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Pointing Devices
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Reading Tools
Input devices “read” directly from paper and convert
printed information into bit patterns that can be
processed by the computer.
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Optical-mark readers
Bar-code readers
Magnetic-ink character readers
Wand readers
Pen scanners
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Digitizing the Real World
Scanner
Digital camera
Speech recognition
Sensing devices
Audio and video digitizers
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Scanners
Scanners capture and digitize printed images. There
are several types of scanners:
 Flatbed scanners
 Handheld scanners
 Sheet-fed scanners
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Digital Cameras
Digital cameras capture snapshots and store them
as bit patterns on disks or other storage media.
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Video Digitizers
Video digitizers capture input from video sources such as
video camera and convert it to a digital signal that can be
stored in memory and displayed on a computer screen.
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Audio Digitizers
Audio digitizers capture
spoken words, music and
sound effects and convert
them to digitized sounds.
These sounds can be
stored in a computer’s
memory and modified
with computer software.
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Sensing Devices
Sensing devices are used to monitor temperature,
humidity, pressure and other physical quantities.
The data collected provides data for use in
robotics, environmental climate control, weather
forecasting and other applications.
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Output: From Pulses to People
Screen Output
Paper Output
Sound Output
Controlling Other Machines
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Screen Output
A monitor or video display terminal (VDT)
displays characters, graphics, photographic
images, animation and video.
 Video adapter—connects the monitor to the computer
 VRAM or video memory—a special portion of RAM
to hold video images (the more video memory, the
more detail of a picture displayed)
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Screen Talk
Monitor size - measured as a diagonal line across
the screen.
Pixels (or picture element) - tiny dots that compose
a picture
Resolution - the number of pixels displayed on the
screen (the higher the resolution, the closer
together the dots)
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Image Quality
Image quality is affected
by resolution and color
depth (or bit depth)
Color depth refers to the
number of different colors
a monitor displays at the
same time
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Examples of Color Depth
1-bit depth
4-bit depth
8-bit depth
16-bit depth
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Monitor Classes
CRT (cathode ray tube)
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LCD (liquid crystal display)
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Cathode Ray Tube (CRT)
The cathode ray tube has the following
characteristics:
 Low cost
 Speedy response time
 Clear image
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Liquid Crystal Display (LCD)
Light-weight
Compact
Flat-panel
Used in overhead projection panels and video
projectors to project computer images
More expensive than CRTs
Increasingly being seen with desktop computers
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Paper Output
Printers produce paper
output or hard copy
2 kinds of printers:
 Impact printers
 Non-impact printers
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Impact Printers
Line printer
 Used by mainframes to
produce massive printouts
 Limited to printing characters
Dot matrix printer
 Images created by a matrix of
tiny dots
 Low print quality
 Low cost
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Non-impact Printers
Laser Printer
 A laser beam reflected off
a rotating drum to create
patterns of electrical charges
 Faster and more expensive
than dot matrix printer
 High-resolution output
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More on Non-impact Printers
Ink-jet Printer
 Sprays ink onto paper to
produce printed text and
graphic images
 Prints fewer pages/minute
than laser printer
 High-quality color costing
less than laser printer
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Additional Output Devices
Multifunction peripheral or MFP combines a
scanner, printer and a fax modem.
A plotter is an automated drawing tool that can
produce large, finely scaled engineering
blueprints and maps.
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Output You Can Hear
A sound card allows the
PC to accept microphone
input, play music and
other sounds through
speakers or headphones.
Synthesizers are included
in sound cards and have
specialized circuitry
designed to generate
sounds electronically.
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Controlling Other Machines
Output devices take bit patterns and turn them into nondigital movements.
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Robot arms
Telephone switchboards
Transportation devices
Automated factory equipment
Spacecraft
Digiscents
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Rules of Thumb: Ergonomics &
Health
Choose equipment that’s ergonomically designed
Create a healthy workspace
Build flexibility into your work environment
Rest your eyes
Stretch to loosen tight muscles
Listen to your body
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Storage Devices: Input Meets
Output
Secondary storage devices are computer
peripherals capable of performing both input
and output functions
Information is stored semi-permanently on
tape and disk drives
Examples of storage devices
 Magnetic tapes and disks
 Zip, Jaz and SuperDisks
 Optical disks
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Magnetic Media
Magnetic tapes
 Sequential access
 Can store large amounts of information in a
small space at a relatively low cost
 Limitation: sequential access
 Used mainly for backup purposes
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Magnetic Media
Magnetic drives
 Random access
 Floppy disks for inexpensive, portable
storage
 Hard disks are non-removable, rigid disks
that spin continuously and rapidly thus
providing much faster access than
a floppy disk.
 Removable media (Zip & Jaz disks)
provide high-capacity portable storage.
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Optical Media
Optical disk drive uses laser beams to read and
write bits of information on the disk surface.
 Not as fast as magnetic hard disks
 Massive storage capacity and reliability
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Types of Optical Media
CD-ROM drives are optical drives that read CD-ROMs.
CD-R are WORM media (write-once, read many).
CD-RW can read CD-ROMs and write, erase and rewrite data
onto CD-R & CD-RW disks.
DVD (digital versatile disks) store & distribute all kinds of
data. They hold between 3.8 and 17 gigabytes of information.
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Solid-state Storage Devices
Flash memory is an erasable memory chip.
 Compact alternative
 No moving parts
 Designed for specific applications such as storing
pictures in digital cameras
 Likely to replace disk and tape storage
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Ports and Slots Revisited
The system or motherboard includes several
standard 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 for attaching a keyboard
and a mouse
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More on Ports and Slots
Other ports are typically included on expansion
boards rather than 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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Internal and External Drives
Hard drive
 Bays
 Hot swapping
CD or DVD
Floppy disk
Zip Drive
SCSI port
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Expansion Made Easy
With the open architecture of the PC and the introduction
of new interfaces, you can hot swap devices.
 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
– high speed makes it ideal for data-intensive work like digital
video
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Putting It All Together with
Networks
A typical computer system might have several
different input, output, and storage peripherals.
The key is compatibility.
Networks blur the boundaries between computers.
Networked computers may have access to all the
peripherals on a system.
The computer is, in effect, just a tiny part of a global
system of interconnected networks. b
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