Hardware Basics: Peripherals

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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.

• 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 computers 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 adapterconnects the monitor to the
  computer
• VRAM or video memorya 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
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Monitor Classes

• CRT (cathode ray tube)

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 non-digital movements.

• Robot arms
• Telephone switchboards
• Transportation devices
• Automated factory equipment
• Spacecraft
• Digiscents

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Rules of Thumb Ergonomics Health

• Choose equipment thats 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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