Chapter 4
Input and Output
Understanding Computers, 12th Edition, Enhanced
Chapter 4
1
Overview
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This chapter covers:
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Keyboards and pointing devices
Scanners and related devices
Biometric and multimedia input devices
Various types of display devices
Various types of printers
Multimedia output devices
Understanding Computers, 12th Edition, Enhanced
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Input and Output
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Input devices convert data from the user into a form
understood by the computer.
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Output devices convert the processed 0s and 1s
into a form that the user can understand.
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Hard copy—permanently recorded, such as on
paper.
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Soft copy—temporarily recorded, such as on a
computer screen.
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Keyboards
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Computers usually use a keyboard for text-based
input.
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Keyboards can differ in number of keys, key
arrangement, types of special keys, and touch.
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Function keys enable software packages to be
customized to meet a user's applications needs.
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The numeric keypad makes it easy to enter numbers
quickly.
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Keyboards, Cont’d.
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Portable
keyboards and
thumb pads are
increasingly being
used with portable
PCs and mobile
devices.
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Pointing Devices
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Mice
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The mouse is the most common type of pointing
device.
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Can be mechanical or optical.
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Used to select onscreen objects, issue commands,
move objects, scroll through documents, etc.
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Pointing Devices, Cont’d.
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Electronic pens (light pen, stylus)
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An alternative to the mouse to select objects or to write
or draw on the screen.
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Commonly used with:
 Graphics tablets
 Digital portfolios and digital pens
 Signature capture devices
 Pen-based computers
 Handwriting recognition technology
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Pointing Devices, Cont’d.
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Touch screens
 Used when other input
devices are
impractical.
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Often used when
consumer input is
required, as in
consumer kiosks.
Understanding Computers, 12th Edition, Enhanced
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Pointing Devices, Cont’d.
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Other common pointing devices
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Joysticks and other gaming devices
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Trackballs
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Pointing sticks
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Touch pads
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Scanners and Related Devices
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Source data automation involves converting source
documents to digital form or initially collecting data in
digital form.
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Often involves scanning or reading devices.
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Scanners
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Scanners (optical scanners) convert hard-copy images of
text pages, photographs, and drawings into digital form.
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Types of scanners:
 Flatbed
 Sheet-fed
 Handheld
 Drum
 Three-dimensional
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Quality of scanned images are measured by resolution.
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Optical Mark Readers (OMRs)
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Read optical marks, such as on:
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Exams
Census forms
Voting ballots
Lottery forms
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Bar-Code Readers
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Bar code—an optical code consisting of several bars
of varying widths that form a unique, identifiable code.
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Read by fixed or portable bar-code readers.
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Common types:
 Universal Product Code (UPC)
 POSTNET code
 Proprietary codes for shippers, hospitals, and
other businesses
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Optical Character Recognition (OCR)
Devices
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Optical characters are designed to be identifiable by
humans as well as OCR device.
Widely used in turnaround documents, such as
monthly bills.
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Magnetic Ink Character Recognition
(MICR) Readers
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Used primarily for processing checks.
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MICR readers
can read the
special magnetic
characters
and sort and
process
documents
accordingly.
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Biometric Input Devices
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Used to input biometric data about a person.
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Biometric data is based on unique physical
characteristics (e.g. fingerprint) or personal traits (e.g.
voice).
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Used for access and to verify transactions.
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Biometric readers can be stand-alone or built into
keyboards or other hardware devices.
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Multimedia Input Devices
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Digital cameras record data onto digital media
instead of conventional film or tape.
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Images can be transferred to a PC via a cable or the
storage media (such as a flash memory card with a
digital still camera).
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Can be digital still cameras or digital video cameras.
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Multimedia Input Devices, Cont’d.
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Digital still cameras
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Images are usually stored on flash memory cards.
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Photos can usually be immediately previewed and deleted, if
needed.
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Photos are easily transferred to a PC to be stored and/or
printed.
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Camera quality is measured in mexapixels.
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Digital photos can be printed at home or at a photo lab.
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Multimedia Input Devices, Cont’d.
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Digital video cameras
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Store images on digital media (typically digital tape or
optical discs).
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Video can be easily transferred to a PC for editing
and/or burning onto a DVD.
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Can be used for videoconferencing and Web cams.
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Multimedia Input Devices, Cont’d.
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Audio input devices
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Voice-input systems convert spoken words to digital
data.
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Voice input can be used to input data or commands
into a PC as well as for telephony.
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Music-input systems can input and record music (either
original compositions or via a CD or DVD player).
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Display Devices
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Display device characteristics
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Color vs. monochrome displays
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Size (measured diagonally)
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Screen resolution
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Graphic standards
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Display Devices, Cont’d.
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CRT (cathode-ray tube) monitors—display images
similar to conventional televisions.
Quality is measured in dot pitch.
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Display Devices, Cont’d.
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Flat-panel displays—form images by manipulating
electronically-charged chemicals or gases between
thin panes or glass or plastic.
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Common types:
 Liquid crystal displays (LCD)
 Gas plasma
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Used for monitors, televisions, handheld devices, and
other consumer products.
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Display Devices, Cont’d.
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Smart displays
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HDTV monitors
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Data projectors
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Emerging display technologies and applications
(e.g. flexible displays, e-paper, integrated displays,
etc.)
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Printers
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Printer characteristics
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Printer resolution—measured in dots per inch (dpi)
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Impact vs. non-impact printing
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Color vs. black and white
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Personal vs. network printers
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Speed
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Laser Printers
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The standard for business documents.
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Work similarly to photocopy machines; print
with toner powder.
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Are usually black and white, though color
laser printers are available.
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Fast print speed; print one page at a time.
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Ink-Jet Printers
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Print with tiny drops of liquid ink.
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Typically print in color.
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Often the choice for home use.
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Print fairly slowly, one line at a time.
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Quality not quite as good as a laser printer.
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Special Purpose Printers
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Photo printers
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Bar-code printers
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Label printers
Portable printers
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Plotters and wide-format
ink-jet printers
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Fax machines
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Multifunction devices
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3D Printers
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Multimedia Output Devices
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Speakers
Voice-output
systems- sometimes
called text-to-speech
systems
Headphones and
Headset
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