Understanding Computers, Chapter 4

Report
Understanding Computers
Today and Tomorrow 12th Edition
Chapter 4:
Input and Output
Learning Objectives
• Explain the purpose of a computer keyboard and the
types of keyboards widely used today.
• List several different pointing devices and describe
their functions.
• Describe the purposes of scanners and readers and
list some types of scanners and readers in use today.
• Understand how digital cameras differ from
conventional cameras.
• Explain how audio input is accomplished.
• Describe the characteristics of a display device and
explain some of the technologies used to display
images.
• List several types of printers and explain their function.
• Understand which hardware devices are used for
audio output.
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Overview
• This chapter covers:
– Different types of keyboards and pointing devices
– Types of scanners, readers, and digital cameras
and what they are used for
– Audio input devices
– Types of display devices and how they work
– Types of printers and how they work
– Audio output
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Keyboards
• Keyboard: An input device containing keys, arranged
in a typewriter configuration, used to input letters,
numbers, and other symbols
– Can be wired or wireless
• Most PCs today are designed to be used with a
keyboard
• Contains
– Standard alphanumeric keys
– Numeric keypad
– Function keys
– Directional keys and special keys
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Keyboards
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Keyboards
• Keyboards are increasingly including alternate input
tools
– Touch pads
– Scroll wheels
– Some also include built-in display screens
• Portable PCs and mobile devices often use:
– Thumbpad
– Slide-out keyboard
– Pen or touch input
– Portable keyboard
– Virtual keyboard is an emerging possibility
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Keyboards
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Pointing Devices
• Pointing device: An input device that moves an
onscreen pointer (arrow or insertion point) to allow the
user to select objects on the screen
• Usually buttons on the device are used to select
objects
• Common types of pointing devices:
– Mouse
– Electronic pen
– Touch screen
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The Mouse
• Mouse: A pointing
device the user
slides along a flat
surface to move a
pointer around the
screen and clicks its
buttons to make
selections
– Older mechanical
mice use a ball
– Newer optical or
laser mice track
movements with
light
– Can be wireless
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The Electronic Pen and Stylus
• Electronic pen: Device used to select objects, as well
as to draw or write electronically on the screen
• Also called tablet pen, digital pen, stylus
• Commonly used with pen-based PCs
– Used to issue commands and input data
– If handwriting recognition is used, written text can
be converted to editable typed text
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Handwriting Recognition
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The Electronic Pen and Stylus
• Also used with:
– Digital writing systems
– Graphics tablets
– Signature capture devices
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Touch Screens
• Touch screen: Display device that is touched with the
finger to issue commands or otherwise generate input
to the connected PC
• Used with:
– Desktop and portable PCs
– Mobile phones and mobile devices
– Interactive whiteboards
– Consumer kiosks
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Touch Screens
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Other Pointing Devices
• Joysticks,
gamepads, and
other gaming
devices
• Trackballs
• Control buttons and
wheels
• Touch pads
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Scanners, Readers, and Digital Cameras
• Source documents: Documents containing data that
already exists in physical form (order form,
photograph, invoice, check, or price label)
• Source data automation: Capturing data directly from
a source document
– Saves time
– Increases accuracy
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Scanners
• Scanner (optical scanner): Input
device that reads printed text and
graphics and transfers them to a
computer in digital form
– Can scan photos, documents,
drawings, (flat objects)
– Data is typically input as a single
image
– If optical character recognition
(OCR) is used, text is input as
editable, typed text
• Types of scanners
– Flatbed
– Drum
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― Handheld
― 3D
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Scanners
• Optical resolution: Quality of scanned images
– Measured in number of dots per inch (dpi)
– Can often be specified when image is scanned
– Can be changed when scanned image is edited
– Varies with scanner used
•
Pixel: Smallest colorable area
in an electronic image
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Barcode Readers
• Barcode readers: Input devices
that read barcodes
• Barcode: Machine-readable
code that represents data as
a set of bars
– Common types
• Universal Product Code
(UPC)
• ISBN
• Code 39
• POSTNET code
• High-capacity color
barcode (HCCB)
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Radio Frequency
Identification Readers
• Radio frequency identification (RFID): Technology
used to store and transmit data located in RFID tags
• RFID tag: Contains tiny chips and radio antennas
– Attached to objects for identification purposes
– Read by RFID readers
– Tags only need to be within range of the reader,
rather than in the line of sight
• Applications
– Tracking inventory and assets
– Electronic tolls
– Electronic payments (Near Field Communication)
– Security
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Radio Frequency
Identification Readers
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Optical Mark Readers (OMRs)
• Optical Mark Readers (OMRs): Input data from special
forms to score or tally exams, questionnaires, ballots
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Optical Character Recognition Devices
• Optical Character Recognition (OCR): Reads optical
characters that are designed to be identifiable by
humans as well as OCR devices
– Most machines today are designed to read several
standard OCR fonts
– Used to process turnaround documents like
monthly bills
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Magnetic Ink Character
Recognition (MICR) Readers
• Magnetic ink character recognition (MICR) readers:
Read MICR characters
– Used primarily for banking
– MICR readers read the special magnetic
characters and sort/process checks
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Biometric Readers
• Biometric data: Based on unique physiological
characteristics or personal trait
– Fingerprint
– Hand or face geometry
– Iris of the eye
– Voice or signature
• Biometric readers: Used to input biometric data
– Can be stand-alone or built into another piece of
hardware (keyboard, mouse)
– Also being built into computers and storage
devices to allow access only by authorized
individuals
– Most often used for access control and to verify
transactions
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Biometric Readers
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Digital Cameras
• Digital cameras: Record images on digital storage
medium rather than film
– Can either be still cameras or video cameras
– Typically use flash memory for storage
– Images can be edited, posted to a Web page,
burned to a CD or DVD disc, etc.
• Digital still cameras
– Available in a wide variety of sizes and capabilities
– Photos can be transferred to a PC or printer
– Camera quality is measured in megapixels
• Digital video cameras
– Digital camcorders
– PC video cameras (PC cams, Web cam)
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Digital Cameras
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Audio Input
• Audio input: The process of entering audio data into
the computer
– Voice (narrations, podcasts, etc.)
– Music (from CDs, MIDI keyboards, etc.)
• Voice input systems (speech recognition systems)
– Enable a computer to recognize the human voice
– Consist of a microphone or headset and
appropriate software
– Can be used to dictate text or commands into a PC
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Voice Input Systems
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Display Devices
• Display device: Presents output visually
– Monitor: Display device for a desktop PC
– Display screen: Screen built into a variety of
devices
• Notebook and handheld PCs,
• Mobile phones and mobile devices
• E-books readers, digital photo frames, and other
consumer devices, and many other devices
• Digital signage systems
• E-paper
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Display Devices
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Display Device Characteristics
•
•
•
•
•
•
•
Color vs. monochrome displays
CRT vs. flat-panel display
Size
Screen resolution
Wired vs. wireless
2D vs. 3D
Digital TV and HDTV
capabilities
• Touch screen capabilities
• Video card being used determines some of the
characteristics (bit depth, video RAM, connections,
etc.)
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Screen Resolution
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Flat-Panel Display Technologies
• Liquid crystal displays (LCDs): Use charged liquid
crystals between sheets of glass or plastic
– Requires backlighting
• LED (Light emitting diode): Used in displays as well as
a variety of consumer products
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Flat-Panel Display Technologies
• Organic light emitting diode (OLED) displays: Use
emissive organic material to display brighter and
sharper images
– Do not need
backlighting
– Used with
consumer
devices
(portable
digital media
players, TVs,
etc.)
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Flat-Panel Display Technologies
• Special types of OLEDs
– Flexible OLEDs (FOLEDs)
– Transparent OLEDs (TOLEDs)
– Phosphorescent OLEDs (PHOLEDs)
• Interferometric Modulator Displays (IMOD): Essentially
a complex mirror that uses external light to display
images
– Designed initially for mobile phones and portable
devices
– Images are bright and clear, even in sunlight
• Plasma displays: Use layers of gas to display images
– Most often used on large displays
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Flat-Panel Display Technologies
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Data and Multimedia Projectors
• Data projector: Display device that projects all
computer output to a wall or projection screen
– Most data projectors today can project video, in
addition to computer output
– Can be wireless or integrated into devices
– FogScreen systems projects on a thin layer of fog
– Holographic projectors are in development
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Printers
• Printers: Produce hard copy
• Printer Characteristics
– Printing technology used
• Impact vs. nonimpact
– Color vs. black and white
– Personal vs. network printers
– Print resolution
– Print speed
– Possible connections
– Multifunction capabilities
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Printers
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Laser Printers
• Laser printer: Uses toner powder and technology
similar to that of a photocopier to produce images on
paper
– The standard for business documents
– Print one entire page at a time
– Generally faster and have better quality than ink-jet
printers
– Can be black and white or color
– Common print resolution for laser printers is
between 600 and 2,400 dpi
– Use toner cartridges
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Laser Printers
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Ink-Jet Printers
• Ink-jet printer: Sprays droplets of ink to produce
images on paper
– Usually print in color
– Often the choice for home use
– Print fairly slowly, one line at a time
– Quality not quite as good as a laser printer
– Use ink-jet cartridges
• Newer printers with full width printheads are much
faster
• Potential applications for the future
– Dispensing liquid metal, aromas, computer chips
and other circuitry, “printing” human tissue
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Ink-Jet Printers
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Special-Purpose Printers
• Photo printers
• Barcode, label,
and postage
printers
• Portable
printers
• Plotters and
wide-format
ink-jet printers
• 3-D printers
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Audio Output
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•
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Chapter 4
Audio output: Output in the form of voice or music
Speakers
Voice output systems
Headphones and headsets
Earphones and earbuds
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Summary
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Chapter 4
Keyboards
Pointing Devices
Scanners, Readers, and Digital Cameras
Audio Input
Display Devices
Printers
Audio Output
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