Chapter 2:
Input & Output Devices
Computers Are Your Future, Bill Daley
Learning Outcomes
Identify the various types of input and output
devices
Explain the purpose of special keys and list the most
frequently used pointing devices
List the types of monitors and the characteristics
that determine a monitor’s quality
Identify the various types of printers
Identify the devices used to get sound, video, and
images into the computer
2
Input
Input is any data or instructions entered into the
computer’s memory
3
Input Devices: Giving Commands
Keyboard
Mouse
Stylus
Input devices are types of hardware that enable you to get programs,
data, commands, and responses into the computer’s memory
4
Keyboard
The keyboard allows the computer user to enter
words, numbers, punctuation, symbols, and special
function commands into the computer’s memory
5
Types of Keyboard
Enhanced / Extended
Ergonomic
Keyboard
Keyboard
Enhanced or Extended keyboard – Typically 101 keys laid
out in the QWERTY fashion; connected to the computer by
a serial cable
Cordless keyboard – Uses infrared or radio wave signals
Ergonomic keyboard – Designed to help prevent
Cumulative Trauma Disorder (CTD) or damage to nerve
tissues in the wrist and hand due to repeated motion
6
Mouse
The mouse is the most widely used pointing device
A mouse is palm sized
Asthe mouse is moved, its movements are mirrored by the on-
screen pointer
Mouse pad – clean, flat surface for mouse movement
7
Types of Mouse
Wheel
Mouse
Cordless
Mouse
Wheel mouse – Contains a rotating wheel used to scroll
vertically within a text document; connects to PS/2 port
or USB port
Cordless mouse – Uses infrared signals to connect to
the computer’s IrDA port; it must be within sight of the
receiving port
8
PS/2 Port
The color-coded PS/2 connection ports:
Purple for keyboard
Green for mouse
Other Types of Pointing Devices
Trackball Touch
Screen
Pointing
Stick Joystick
Touch Pad Pen
10
How a Mouse Works
Mouse buttons enable the user to initiate actions
Clicking (left-, right-, or double-clicking) allows
the user to select an item on the screen or
open a program or dialog box
Click and drag – Holding down the left mouse
button and moving the mouse enables the user
to move objects on the screen
11
Image Processing Systems: Scanners
Image processing systems are used in business,
industry, and science to input data without manually
keying it in
Scanners
12
Image Processing Systems: Scanners
Magnetic-ink character recognition (MICR) – Used by
banks to process checks
MICR
13
Optical Mark Reader (OMR) – A scanning device that
senses the marks from pencils
Alternative Input Devices
Scanners
Flatbed Barcode reader
Microphone – Speech
recognition
15
Alternative Input Devices
Digital Camera Digital Video
Video-conferencing
Web Cam
16
Speech Recognition - Microphone
Speech recognition is a type of input in which the computer recognizes
words spoken into a microphone
Special software and a microphone are required
A microphone – an input device that converts sound input into electrical
signals
Latest technology uses continuous speech recognition where the user does
not have to pause between words
17
Digital Cameras
The image’s light falls on a charge-coupled device
(CCD) which transforms the light’s patterns into
pixels
Images are stored in the camera using flash memory.
The most popular types are CompactFlash, SD,
MICRO SD, MINI SD, Memory Stick and etc...
Photo-editing programs enable the user to edit the
images
18
Memory card
19
Digital Video camera
A video capture board transforms analog video
into digital video
Codecs or compression/decompression standards
are used to compress digital video files
A frame rate of 24 frames per second (fps) is
needed to produce a continuous smooth action
20
Video-conferencing
Videoconferencing uses digital video technology to
simulate face-to-face meetings
Whiteboards, which are a part of the screen, can be
used to write or draw
21
Web Cam
A Web cam provides low-
resolution video-conferencing
for Internet users
The images are small and jerky
22
Output Devices
Output devices are peripheral devices that enable
users to view or hear the computer’s processed data
Visual output – Text, graphics, and video
Audio output – Sounds, music, and synthesized
speech
23
Visual Display System
A visual display system is composed of two parts:
Display card
Monitor
24
Display card
A display card is also called video card or graphics card
It plugs into an expansion slot on the motherboard
It contains memory called video RAM (VRAM)
It is designed to work with digital or analog monitors
It converts digital signals to analog
It determines a monitor’s maximum resolution
(VGA/Super VGA)
It determines a monitor’s refresh rate
3D display card – Enables 3-dimensional images
Multi-display video adapter – Permits a connection of two
monitors at a time
25
Monitors
CRT LCD
A monitor is a peripheral device which displays
computer output on a screen.
Screen output is referred to as soft copy.
Types of monitors:
Cathode-ray tube (CRT)
Liquid Crystal Display (LCD or flat-panel)
26
Cathode-ray tube (CRT)
Resembles televisions
Uses picture tube technology
Less expensive than a LCD monitor
Takes up more desk space and uses more energy
than LCD monitors
27
Liquid Crystal Display (LCD)
Cells sandwiched between two
transparent layers form images
Used for notebook computers,
PDAs, cellular phones, and personal
computers
More expensive than a CRT monitor
Takes up less desk space and uses
less energy than CRT monitors
28
Monitor Specifications
Screen size – The diagonal measurement of the screen
surface in inches (15, 17, 19, 21)
Resolution – The sharpness of the image determined by
the number of horizontal and vertical dots (pixels) that the
screen can display (800 x 600, 1024 x 768, 1600 x 1200)
Refresh rate – The speed at which the screen is redrawn
(refreshed) and measured in Hertz (Hz) (60Hz, 75Hz)
29
Printers
A printer is a peripheral device that produces a
physical copy or hard copy of the computer’s output
Two basic types:
Impact printer
Non-impact printer
30
Impact Printer
Impact printer
Dot-matrix
An impact printer is a printer that has a print head that contacts the
paper to produce a character
It uses ink ribbon
It is noisy, produces Near-letter quality printouts, and is not commonly
used today
Dot-matrix – Pins are used to make characters
31
Non-impact Printer
Inkjet Laser
The non-impact printer is the most commonly used printer
today
It works quietly compared to an impact printer
Laser printer works like a
Inkjet printer, also called a
bubble-jet, makes characters copier
by inserting dots of ink onto Quality determined by dots
paper per inch (dpi) produced
Color printers available
Letter-quality printouts
Cost of printer is inexpensive High initial costs but
but ink is costly cheaper to operate per page
32
Multifunction Printer
A multifunction printer combines the functions of a
non-impact printer, scanner, fax machine, and copier
in one unit
33
Plotter
A plotter is a printer that uses a pen that moves over
a large revolving sheet of paper
It produces high-quality images
It is used in engineering, drafting, map making, and
seismotology
34
Audio Output
Audio output is the ability of the computer to
output sound
Two components are needed:
Sound card – Plays contents of digitized
recordings
Speakers – Attached to sound card
Digital formats include WAV, MPEG, MP3, and MIDI
35
Summary
•• Input
Inputisisthe
thesoftware,
software,data,
data,and
andinformation
informationthat
thatisis
entered
enteredintointothe
thecomputer’s
computer’smemory
memory
•• Input
Inputdevices
devicessuch suchasasthe
thekeyboard,
keyboard,mouse,
mouse,andand
trackball
trackballenable
enablethetheuser
usertotoenter
enterdata
data
•• AApointing
pointingdevice
deviceenables
enablesthetheuser
usertotocontrol
control
movements
movementsofofan anon-screen
on-screenpointer
pointer
•• Speech
Speechrecognition
recognitionsoftware
softwareenables
enablesthetheuser
usertoto
enter
enterdata
datainto
intoaacomputer
computerby byspeaking
speakinginto
intoaa
microphone
microphone
•• Monitors
Monitorsenable
enablethe theuser
usertotoview
viewthe
thecomputer’s
computer’s
processed
processeddata; data;the
theoutput
outputisisknown
knownas assoft
softcopy
copy
36
Summary
•• The
Thetwo
twotypes
typesofofmonitors
monitorsarearethe
theCRT
CRTandandthe
theLCD
LCD
•• AAmonitor’s
monitor’squality
qualityisismeasured
measuredby byscreen
screensize,
size,
resolution,
resolution,and
andrefresh
refreshrate
rate
•• Printers
Printersproduce
producepermanent
permanentversions
versions(hard
(hardcopies)
copies)ofof
the
thecomputer’s
computer’soutput
output
•• The
Thetwo
twobasic
basictypes
typesofofprinters
printersare
arethe
theinkjet
inkjetand
andlaser
laser
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