Hardware Computer and Peripherals Computer Hardware Overview

Hardware Computer and Peripherals Computer Hardware Overview
Computer and Peripherals
n Computer
uRefer only to the Central processing unit
(CPU), the circuitry that processes the data, and
the computer’s memory.
n Peripherals
uAll additional hardware components grouped
around the CPU and memory
Hardware
Part 1: Inside the System Unit
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1
Computer Hardware Overview
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System Unit
nIt is a Box-like case
that contains
computer’s
electronic
components
nSometimes called
the Chassis
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1
Exposed System Unit
How do computers represent data?
n Most computers are digital
n Recognize only two discrete states: on or off
on
1
off
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Binary System
Electronic
Charge
0
1
0
1
0
1
0
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0
6
What is a byte?
n Number system with two unique digits: 0 and 1
Binary
Digit (bit)
1
n Eight bits grouped together is a byte
Electronic
State
8-bit byte for the number 3
8-bit byte for the number 5
8-bit byte for the capital letter T
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2
Three Popular Coding Systems to
Represent Data
°
°
°
How is a Character Sent from
Keyboard to Computer?
ASCII - American
Standard Code for
Information Interchange
EBCDIC - Extended
Binary Coded Decimal
Interchange Code
Step 1: Press letter T
Step 2: Electronic signal for
letter T sent to system unit
Step 3: Signal changed to its
ASCII code (01010100) and
stored in memory
Unicode - coding
scheme capable of
representing all world’s
languages
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Step 4: After processing, binary
code for letter T is converted to
image on output device
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Central Processing Unit (CPU) ?
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Components of the CPU
n Interprets and carries out basic instructions that operate a
computer
n Also called the Processor
CPU
Control
Unit
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Arithmetic/
Logic Unit
(ALU)
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3
Control Unit
Machine Cycle?
°Four operations of the CPU comprise a machine cycle
°Also called instruction cycle
° Directs and coordinates
operations in computer
Control unit repeats
four basic operations:
Control Unit
• Instruction time (i-time) - time taken to fetch and decode
• Execution time (e -time) - time taken to execute and store
° Fetch - obtain program
instruction or data item from
memory
° Decode - translate instruction into
commands
° Execute - carry out command
° Store - write result to memory
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An example of a machine cycle
e-time
i-time
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Available CPU Packages
100 x 52
Student enters
math problem
(100 x 52) into
computer’s
memory
single edge contact (SEC) cartridge
dual inline package (DIP)
Result in
memory
displays on
monitor ’s
screen
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flip chip-PGA
(FC-PGA) package
15
© Peter Lo 2002
pin grid array (PGA)
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4
CPU’
CPU
’s speed Measuring
°
Two Designs used for the CPU
According to
how many
millions of
instructions per
second (MIPS) it
can process
CISC
(complex instruction se t
computing)
° Supports large number
of instructions
° CPU executes complex
instructions more
quickly
RISC
(reduced instruction
set computing)
°
°
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Arithmetic/Logic unit (ALU)
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Supports smaller
number of
instructions
CPU executes simple
instructions more
quickly
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Pipelining
n CPU begins executing second instruction before
completing first instruction. Results in faster processing
n CPU component that performs execution part of
the machine cycle
Machine Cycle (without pipelining)
Comparison
(greater than, equal
to, or less than)
Arithmetic
(addition, subtraction,
multiplication, and
division)
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d.
.an
r. .not.
.oLogical
Machine Cycle (with pipelining)
Instruction 1
Instruction 2
(AND, OR,
NOT)
Instruction 3
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Instruction 4
20
5
Register
°
Temporary
storage area
that holds
data and
instructions
System Clock
Stores
instruction
while it is
being decoded
Stores location
from where
instruction was
fetched
n Synchronizes all computer operations
n Each tick is clock cycle
Stores results
of calculation
Stores data while
ALU processes it
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MHz - one million
ticks of system clock
GHz – one billion ticks
of system clock
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How do personal computer
processors compare?
Microprocessor
n Single processor chip found in personal computers
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Coprocessor
Parallel Processing
° Using
multiple processors
simultaneously to execute
program faster
Chip that assists
processor in
performing
specific tasks
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One type is a
floating-point
coprocessor,
also known as a
math or numeric
coprocessor
° Requires
25
Memory: The CPU’
CPU’s Electronic
Scratchpad
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special software
to divide problem and
bring results together
26
How is memory measured?
n Memory is the temporary storage area for
operating system, application programs, and data
n It consists of one or more chips on motherboard
n Each byte stored in unique address
n Memory is measured by number of bytes available
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Random Access Memory (RAM)
Two types of System Unit Memory
volatile memory
Loses its contents when
thecomputer's
computer'spower
power is
isturned
turnedoff
off
n Memory chips that can be read from and written to
by processor
n Most RAM is volatile
n The more RAM a computer has, the faster it
operates
nonvolatile
memory
Does NOT lose its
contents when
computer ’s power is
turned off
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memory
module
29
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Two Basic Types of RAM chips
Cache
n Dynamic RAM (DRAM)
uMost common type
uAlso called main memory
n Static RAM (SRAM)
u Used for special applications such as cache
u Faster and more reliable than DRAM chips
n Helps speed computer processes by
storing frequently used instructions
and data
n Also called Memory Cache, Cache
Store , or RAM Cache
n L1 cache built in processor
n L2 and L3 cache not built in
processor
n L2 advanced transfer cache most
common
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Read--Only Memory (ROM)
Read
Types of ROM
n Memory chips that contain data, instructions, or
information that is recorded permanently
Data can only
be read;
cannot be
modified in
ROM
ROM is
nonvolatile —
Contents not lost
when computer is
turned off
n Firmware
uROM chips manufactured with permanently written
data, instructions, or information
BIOS
(basic input/output system)
Stored on ROM
Sequence of instructions
computer follows to load
operating system and other
files when you turn on the
computer
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n PROM (Programmable Read-Only Memory)
uBlank ROM on which you can place items permanently
n EEPROM (Electrically Erasable Programmable Read-Only Memory)
uType of PROM containing microcode programmer can
erase
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Flash Memory
CMOS
n Nonvolatile memory that can be erased
electronically and reprogrammed
n Used with handheld computers and digital
cameras, cellular phones, and automobiles
n CMOS stand for Complementary Metal-Oxide
Semiconductor memory
n Stores information about the computer
utype of disk drives
ukeyboard
umonitor
ucurrent time and date
n Uses battery to retain information when computer
is turned off
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Memory Access Time
BUS
°
n Speed at which processor can access data from memory
directly
n Measured in nanoseconds (ns), which is one billionth of a
second
n It takes 1/10 of a second to blink your eye; a computer can
perform up to 10 million operations in same amount of
time
°
°
°
Channel that allows devices inside
computer to communicate with
each other
System bus connects processor
and RAM
Bus width determines number
of bits transmitted at one time
Word size determines number
of bits processor can interpret
and execute at a given time
processor
system
bus
RAM
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Expansion Bus
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Expansion Slot
n Allows processor to communicate with peripherals
fastest
next fastest
next fastest
slowest
memory
° An opening, or
socket, where
circuit board is
inserted into
motherboard
° Expansion card
inserted in
expansion slot
processor
expansion
card
PCI© bus
Peter Loexpansion
2002
slots
ISA bus expansion slots
39
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expansion
slot
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How are expansion cards used?
Plug and Play
n Computer automatically can configure cards and
other devices as you install them
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PCMCIA card
Flash Memory Card
n Credit card-sized device used to add capabilities to
notebook computers
n PCMCIA stand for Personal Computer Memory Card
International Association
n Uses include modem, additional memory, and storage
n Adds memory to handheld computers, digital
music players, cellular telephones, and similar
devices
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Port
°Connects
external
devices to
system unit
mouse
keyboard
Different Types of Connectors
USB
USB
serial port
printer (parallel
port)
speaker
monitor
microphone
game port
network
telephone
line out
telephone line
in
FM reception
svideo out
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Serial Port
°Transmits one bit of
data at a time
°Used to connect
slow-speed devices,
such as mouse,
keyboard, modem
45
cable TV
serial
transmission
of data
byte
representation
for number 5
(00110101)
byte
representation
for number 5
(00110101)
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byte representation
1
Parallel Port forbytenumber
representation
for number 3
byte representation
byte
representation
for number 5
(00110101)
° Connects devices fornumber 5
that can transfer
more than one bit
at a time, such as a
printer
DB-9 female
connector
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DB-9 male
connector
46
DB-25 male
connector
47
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DB-25 female
connector
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12
DVD-ROM
drive
Universal Serial Bus port (USB)
Bay
n Connector that supports newer peripherals and plug and
play
n Other popular ports include 1394, MIDI, SCSI, and IrDA
n Open area inside
system unit used
to install additional
equipment
CD-RW
drive
Zip drive
empty drive
bay
floppy disk
drive
1394 port
USB port
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What ports are on a notebook
computer?
Power Supply
n Converts alternating current (AC) to direct current
(DC)
n Some peripheral devices have AC adapter
keyboard/mouse
port
IrDA
port
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51
serial port
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parallel
port
video port
USB port
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How is data transferred from a
handheld computer?
n An IrDA port allows the handheld computer to
communicate wirelessly with other computers or devices
n Handheld computers also can rest in a cradle, so you can
transfer data to your desktop computer
Hardware
Part 2: Data Storage
IrDA port
cradle
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How does storage differ from
memory?
What is storage?
n Media and devices used to store and retrieve data,
instructions, and information
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n Stores items for
future use, rather
than temporarily
n Storage is
nonvolatile, rather
than volatile
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When you
want to work
with a file,
you read it
from storage
and place it in
memory
When you are
finished with
the file, you
write it from
memory into
storage
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14
What is a storage device and a
storage Medium?
How does volatility compare?
storage
device
Contentsof
of
Contents
storage
storage
retainedwhen
when
retained
powerisisoff
off
power
Screendisplay
displayand
andcontents
contents
Screen
ofmost
mostRAM
RAM(memory)
(memory)
of
erased
when
power
off
erased when power isisoff
57
Reading and Writing
What is access time?
writing
Memory
(RAM)
Hard Disk
speed
cost
Process of
transferring items
from memory to a
storage medium
59
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r
we
slo
les
se
xp
en
siv
e
Compact Disc
Serves as a
source of output
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ter
fas
Serves as a source
of input
Physical material on
which a computer
keeps data,
instructions, and
information
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n Amount of time it
takes device to
locate item on disk
n Defines speed of
disk storage device
reading
Process of transferring data,
instructions, and information
from a storage medium into
memory
storage
medium
mo
re
exp
en
siv
e
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Hardware that records
and retrieves items to
and from a storage
medium
Floppy Disk
Tape
60
15
What is capacity?
n Capacity is the
number of bytes
(characters) storage
medium can hold
Storage
Term
Memory vs. Storage (Summary)
Device
Access Speed
Cost per MB
Cache Memory
Fastest
Highest
RAM
Fast
High
Hard disk
Medium
Medium
1 trillion
CD-ROM Disc
Slow
Low
1 quadrillion
Backup Tape
Very Slow
Lowest
Abbreviation
Number
of bytes
Kilobyte
KB
1 thousand
Megabyte
MB
1 million
Gigabyte
GB
1 billion
Terabyte
TB
Petabyte
PB
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Memory
Storage
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Floppy Disk
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What are the parts of a floppy disk?
n Thin, circular,
flexible film
enclosed between
two liners
n Portable, inexpensive storage medium
n Today’s standard disk is 3.5” wide
liner
shutter
metal
hub
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shell
magnetic
coating
flexible
thin 64
film
16
How are floppy disk drives
designated?
How does a floppy disk drive work?
1: Shutter moves to
expose recording
surface on disk
4: Motor causes
floppy disk to spin
One floppy drive
drive A
5: Motor positions
read/write heads
over correct
location on disk
Two floppy
drives
2: Signal sent to control movement
of read/write heads and disk
3: If write instruction, circuit board
verifies whether disk can be written to
Step 2
Step 1
Step 6
drive A
6: Read/write
heads read data
from or write data
on the floppy disk
drive B
Step 5
Step 4
Step 3
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Tracks and Sectors
n Track is narrow
recording band that
forms full circle on
disk surface
n Sector can store up
to 512 bytes of
data
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Format (for Disk)
n Process of preparing disk for
reading and writing
sector
18 per track
track
80 per
side
80 tracks per side x 18 sectors per track x 2 sides per
disk x 512 bytes per sector = 1,474,560 bytes 67
n Formatting marks bad sectors as
unusable
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How to take care a floppy?
What is a writewrite -protect notch?
n Small opening
with a cover that
you slide
n Protects floppy
disks from being
erased
accidentally
n Proper care helps maximize disk’s life
n Floppy disk can last at least seven years
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notchopen
open
notch
meansyou
you
means
cannotwrite
write
cannot
onthe
thedisk
disk
on
notchclosed
closed
notch
meansyou
you
means
can
write
on
can write on
thedisk
disk
the
write-protected
not write-protected
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High--capacity Disk Drive
High
Hard Disk
n Uses disks with capacities of 100 MB and greater
n Primarily used to backup files and transfer files
n High-capacity storage
n Consists of several inflexible, circular platters that store
items electronically
70
n Components enclosed in airtight, sealed case for protection
hard disk
installed in
system unit
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18
How does a hard disk work?
1: Circuit board controls
movement of head
activator and small motor
4: Head actuator
positions
read/write head
arms over correct
location on
platters to read or
write data
2: Small motor
spins platters
What is a Cylinder?
3: When software
requests disk
access, read/write
heads determine
location of data
Step 2
Step 1
cylinder
track
n Location of a single track
through all platters
n Single movement of
read/write head arms can
read same track on all
platters
Step 3
Step 4
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A head crash!
Disk Cache
n Occurs when read/write head touches platter surface
n Spinning creates cushion of air that floats read/write head
above platter
gapis
ishalf
halfthe
the
gap
n Portion of memory processor uses to store
frequently accessed items
processo
r
diameterof
ofaa
diameter
dust particle
particle
dust
clearance
clearance
betweenhead
head
between
andplatter
platteris
is
and
approximately
approximately
twomillionths
millionths
two
ofan
aninch
inch
of
disk cache
hair
hard disk
read/write head
first request for data
— to disk cache
dust
smoke
gap
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platter
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second request for data — to hard disk
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19
What is a Partition?
n Formatted hard disk
divided into separate
areas called
partitions
n Each partition
functions as if it
were a separate hard
disk drive
Removable Hard Disk?
drive C
Designation for first
partition or for a single
partition on hard disk
one hard disk
divided into
two partitions
© Peter Lo 2002
n Disk drive in which a plastic or metal case
surrounds the hard disk so you can remove it from
the drive
n Used for backup or to transfer files
drive D
Designation for second
partition on hard disk77
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What Windows Utilities Maintain
a Hard Disk Drive?
How does RAID work?
n Disk system that duplicates data, instructions, and
information to improve data reliability
uMirroring has one backup disk for each disk
uStriping stores data across multiple disks
mirroring
(RAID Level 1)
striping
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System
Tools
80
20
Internet Hard Drive?
Advantages of Internet hard drive
n Service on Web that provides storage to computer users
n Most offer free storage
n Revenues come from advertisers
Large audio, video,
and graphics files can
be downloaded to an
Internet hard drive
instantaneously
Others can be
authorized to access
data from your Internet
hard drive
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Compact Disc (CD)
M
-RO
D
C
CD-R
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Allows offsite
backups of data
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How do you use a compact disc?
n Storage medium
n Most PCs include some type of compact disc drive
n Available in variety of formats
+RW
DVD
Files can be
accessed from any
computer or device
with Web access
n CD drives can read
compact discs,
including audio
discs
Pushbutton
button
Push
toslide
slideout
out
to
thetray
tray
the
Insertdisc,
disc,
Insert
labelside
sideup
up
label
CD
- RW
M
-RO
D
V
D
83
© Peter Lo 2002
Pushthe
thesame
same
Push
buttonto
toclose
close
button
thetray
tray 84
the
21
How does a laser read data on a
compact disc?
1: Laser diode shines light
beam toward compact disc
3: Reflected light
deflected to light- sensing
diode, which sends
digital signal of 1.
Absence of reflected
light read as digital
signal of 0.
Compact disc
label
Step 3
1
2
2: If light strikes pit, it
scatters. If light strikes
land, it is reflected back
toward laser diode.
pit
lens
n Typically stores items in single track
n Track divided into evenly sized sectors that store items
land
Compact disc
sectors
lens
0
prism
laser
diode
How data stored on a compact disc?
1
prism
Lightsensing
diode
© Peter Lo 2002
laser
diode
Lightsensing
diode
85
© Peter Lo 2002
Single track spirals
to edge of disc
86
How should you care for a
compact disc?
1: Do not expose
What is a jewel box?
n Protective case for compact disc
to excessive
heat or sunlight
2: Do not eat,
smoke, or drink
near a disc
3: Do not stack
4: Do not touch
underside
5: Store in jewel
box when not in
use
jewel box
© Peter Lo 2002
6: Hold disc by its
edges
87
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88
22
What is a CDCD-ROM?
CD--R (Compact DiscCD
Disc -Recordable
Recordable))
n Compact disc that uses same laser technology as audio
CDs for recording music
n Cannot erase or modify contents
n Compact disc onto which you can record text, graphics,
and audio
n Write on CD-R using CD burner (recorder) or CD-R drive
and special software
n CD-R drive can read and write both audio CDs and
standard CD-ROMs
n Cannot erase disc’s contents
n Typical CD-ROM holds about 650 MB
n Commonly used to distribute software and games
© Peter Lo 2002
89
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CD--RW (compact discCD
disc-rewritable
rewritable))
90
How to Create Audio CD?
1
Step 1: Artist composes song and
creates CD
n Erasable disc you can write on Multiple Times
n Must have a CD-RW disc, CD-RW software,
and CD-RW drive
2a
OR
Step 2b: Song compressed and
stored on Internet
Step 3a: User inserts audio CD into
CD-ROM drive, plays song, and
copies it to hard disk
OR
© Peter Lo 2002
2b
Step 2a: Song stored on audio CD
and purchased by user
91
Step 3b: User downloads song as
audio file to hard disk
Step 4: User copies file to CD-RW
disc
Step 5: User listens to
song on personal
computer or removes
© Peter
2002 to song
CD
and Lo
listens
on portable CD player
3a
5
3b
4
92
23
DVD -ROM (Digital Video DiscDVDDisc ROM)
How does a DVDDVD -ROM store data?
n High capacity compact disc capable of storing
from 4.7 GB to 17 GB
n Must have DVD -ROM drive or DVD player to
read DVD-ROM
n Primarily used for movies
n Next -generation software will be delivered on
DVD
© Peter Lo 2002
n Two layers of pits are used, where lower layer is
semitransparent
n Laser can read through it to upper layer
n DVD+RW is a rewritable DVD
93
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Tape
Sequential Access vs. Direct Access
n Magnetically coated ribbon of plastic capable of storing
large amounts of data and information at a low cost
n Primarily used for backup
n Sequential Access
uReading and writing data consecutively
uMethod used for tape
n Direct Access
uCan locate a particular data item or file
immediately
uMethod used for floppy disks, hard disks, and
compact discs
uAlso called Random Access
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96
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Enterprise Storage System
n Strategy that
focuses on
availability,
protection ,
organization, and
backup of storage
in a company
Miniature Mobile Storage Media
tape
tape library
library
n Handheld devices use to augment internal storage
CD-ROM
CD-ROM
jukeboxes
jukeboxes
RAID
CompactFlash
40 MB
Cartridge
Digital cameras, notebook
computers
Memory Stick
2 to 256 MB
Memory Card
Digital cameras, handheld
computers, notebook computers,
printers, cellular telephones
servers
Microdrive
1 GB
Memory Card
Digital cameras, handheld
computers, music players, video
cameras
SmartMedia
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Storage area network
Network
Network Storage
storage
2 to 128 MB
Digital cameras, handheld
computers, photo printers, 98
cellular telephones
Internet backup
Smart Card
Types of smart cards
n Intelligent smart card contains
processor and has input,
process, output, and storage
capabilities
n Stores data on thin microprocessor embedded in
credit card
n Memory card has only storage
capabilities
Store data such as
photographs, music, books,
and video clips
Store a prepaid dollar amount
that is updated when the card is
used
Store patient records,
vaccination data, and other
healthcare information
smart card
© Peter Lo 2002
Memory Card
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Store tracking information such
as customer purchases or
100
employee attendance
25
Electronic Money
n Means of paying for
goods and services
over the Internet
n Also called
e-money or digital
cash
Bank issues
unique digital
cash numbers
that represent an
amount of money
Microfilm and Microfiche
n Store microscopic images of
documents on a roll or a sheet of film
n Images recorded using a computer
output microfilm (COM) recorder
When you
purchase digital
cash, the amount
of money is
withdrawn from
your bank
account
Microfilm
To use the card,
swipe it through
a card reader
© Peter Lo 2002
Uses a 100- to 215foot roll of film
101
Life expectancies of various media
© Peter Lo 2002
Microfiche
Uses a small sheet
of film, usually
4” x 6”
102
What is a backup?
n Duplicate of file, program, or
disk that you can use if
original is lost, damaged, or
destroyed
ns
io
ct
ru
st
in
inf
orm
ati
on
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103
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ta
da
104
26
What is input?
uUnprocessed
facts, figures, and
symbols
n Instructions
uPrograms
uCommands
Hardware
Part 3: Input and Output
DATA
Susan works 42 hours at $300/hr
n Data
uUser responses
ect
orr ect
re c orr
ES tries a not c
S
are
ON n
SP rd e ies
RE eca entr
ER he tim card
S
U s, t ime
DS rd
Ye , the t
AN eca
No
MS
MM tim
RA
CO nt the
OG ard
i
R
r
p
P ec
tim
hard disk
© Peter Lo 2002
105
© Peter Lo 2002
INSTRUCTIONS
106
What is an input device?
How is the keyboard divided?
n Any hardware component used to enter data, programs,
commands, and user responses into a computer
n Typing area
n Numeric keypad
n Function keys
video input
voice input
function keys
keyboard
scanners
and reading
devices
pointing
device
typing area
© Peter Lo 2002
digital
camera
107
© Peter Lo 2002
numeric keypad
108
27
Portable Keyboard
Ergonomic Keyboard
n Full-sized keyboard you conveniently can attach and
remove from a handheld computer
n Designed to minimize strain on hands and wrists
n Ergonomics incorporates comfort, efficiency, and
safety into design of items in workplace
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© Peter Lo 2002
110
Alternative forms for commands
Mouse
n Many programs allow you to use button, menu, or
function key to obtain same result
n Pointing device that fits under palm of hand
n Controls movement of pointer, also called mouse
pointer, on screen
n Pointer on screen takes several shapes
Command
Button
Menu
Function Key(s)
Copy
Edit|Copy
SHIFT+F2
Open
File|Open
CTRL+F12
Print
File|Print
CTRL+SHIFT+F12
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© Peter Lo 2002
112
I-beam
block arrow pointing hand
28
How does mechanical mouse work?
n Rubber or metal ball is
on its underside
n Movement of mouse
translates into signals
computer understands
mouse
mouse
buttons
buttons
wheel
wheel
button
button
How does an optical mouse work?
n Senses light to detect
mouse’s movement
n More precise than
mechanical mouse
n Connect using a cable or
wireless
wheel
wheel
button
button
back
back
button
button
forward
forward
button
button
optical
optical
sensor
sensor
mousepad
pad
mouse
© Peter Lo 2002
ball
ball
113
© Peter Lo 2002
114
Common mouse operations
Trackball
n Point
n Click
n Right-click
n Double-click
n Drag
n Right-drag
n Rotate wheel
n Press wheel
n Stationary pointing device with a ball on its top
n To move pointer, rotate ball with thumb, fingers,
or palm of hand
© Peter Lo 2002
trackball
115
© Peter Lo 2002
116
29
Touchpad
Pointing Stick
n Small, flat, rectangular pointing device sensitive to
pressure and motion
n Pointing device shaped like pencil eraser
positioned between keys on keyboard
touchpad
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117
© Peter Lo 2002
118
pointing stick
Joystick and Wheel
Light Pen
n Joystick is vertical lever mounted on a base
n Wheel is steering-wheel type input device
n Pedal simulates car brakes and accelerator
n Handheld input device that contains light source or can
detect light
n Press light pen against screen surface and then press button
on pen
joystick
wheel
pedal
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119
© Peter Lo 2002
light pen
120
30
Touch Screen
Stylus
n Touch areas of screen with finger
n Often used with kiosks
n Looks like a ballpoint pen, but uses pressure to write text
and draw lines
n Used with graphics tablets and handheld computers
stylus or pen
touch screen
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121
© Peter Lo 2002
Electronic Signature
Handwriting Recognition
n Pen and graphics tablet used with special software for
handwriting recognition
n Legal as ink signature
n Translates handwritten letters and symbols into
characters that the computer can understand
122
n Also called e-signature
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123
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124
31
How does voice recognition work?
Step 1: Dictate
You’re right!
Natural Language
Engine
Step 2: Convert analog to digital
MIDI (Musical Instrument Digital
Interface)
n External device, such as electronic piano keyboard,
to input music and sound effects
Step 4: Most likely match
selected
… Your write
… You’re right
… Your right
Step 3: Check database for match
your, you ’re
Matches
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125
right, write
How is a data entered into a
handheld device?
126
Digital Camera
stylus
n Allows you to take digital pictures
n Images viewable immediately on camera
n Download to computer
n Post pictures to Web
voice input
handwriting recognition characters
© Peter Lo 2002
stylus
stylus
transfer
data from
desktop
computer
on-screen
keyboard
© Peter Lo
digital
2002 camera
127
portable keyboard
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128
32
How does a digital camera work?
Resolution
1: Take picture
Step 1
2: Image focuses on CCD
n Sharpness and clarity of image
n Higher the resolution, the better the image quality,
but the more expensive the camera
n Pixel (picture element) is single point in electronic
image
n Greater the number of pixels, the better the image
quality
Step 2
3: CCD generates analog
signal that represents
image
4: Analog signal
converts to digital signal
Step 3
Step 4
5: Digital signal processor
(DSP) adjusts quality
Step 5
6: Transfer image to
computer
7: View and manipulate
image
Step 6
Step 7
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130
Video Input
PC Video Camera
n Process of entering full-motion recording into computer
n Also called Video Capture
n Video capture card is expansion card that converts analog
video signal into digital signal
digitalvideo
video
digital
camera
that computer understands
camera
n Digital video camera that allows home user to record, edit,
and capture video and still images, and to make video
telephone calls on Internet
n Also called PC Camera
PC video
camera
n Video compression
© Peter Lo 2002
analogvideo
video
analog
camera
camera
131
© Peter Lo 2002
132
33
Web Cam
Videoconferencing
n Video camera whose output displays on a Web page
n Also called a cam
n Streaming cam shows moving images by sending continual
stream of pictures
n Two or more geographically separated people who use
network on the Internet to transmit audio and video data
n Whiteboard is another window on screen that can display
notes and drawings simultaneously on all participants’
screens
Web cam
video output
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133
Scanner
© Peter Lo 2002
134
How does a flatbed scanner work?
1: Place document
face down
2: Bright light scans
document
n Device that captures data directly from source document
uSource document is original form of data
3: Image reflected
into mirrors
4: Light converted to
analog electrical and
then to digital signal
Step 1
Step 2
Step 3
5: Digital information
sent to computer
OCR
6: Print or save
document
© Peter Lo 2002
flatbed
scanner
135
© Peter Lo 2002
Step 4
Step136
6
Step 5
34
Various types of scanners
Image Processing
Pen or
handheld
n Capturing, storing, analyzing, displaying, printing,
and manipulating images
n Converting paper documents
into electronic form
n Also called Imaging
Flatbed
Drum
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© Peter Lo 2002
138
Sheet-fed
Optical Reader
OCR Font
n Device that uses light source to read characters,
marks, and codes and then converts them into
digital data
uOptical character recognition (OCR)
uOptical mark recognition (OMR)
uBar code scanner
n OCR font, such as OCR-A, used with OCR
devices
n OCR device determines characters’shapes by
detecting patterns of light and dark
n OCR software converts shapes into characters the
computer can understand
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© Peter Lo 2002
140
35
Turnaround Document
Optical Mark Recognition (OMR)
n You return it to
company that
sent it
n Reads hand-drawn pencil marks, such as small
circles or rectangles
numbers are read
by OCR device
when document is
returned
© Peter Lo 2002
141
© Peter Lo 2002
142
Bar Code Scanner
Bar Code
n Uses laser beams to read bar codes
n Identification code that consists of a set of vertical lines
and spaces of different widths
n Universal Product Code (UPC)
Numbersystem
system
Number
characteridentifies
identifies
character
typeof
ofproduct
product
type
Manufacturer
Manufacturer
identificationnumber
number
identification
(Kellogg’s,in
inthis
thiscase)
case)
(Kellogg’s,
Checkcharacter
characterverifies
verifies
Check
accuracyof
ofscanned
scanned
accuracy
UPCsymbol
symbol
UPC
bar code scanners
© Peter Lo 2002
143
© Peter Lo 2002
Itemnumber
number(10
(10oz.
oz.box
box
Item
ofFroot
FrootLoops
Loops144
of
36
Magnetic Ink Character
Recognition Reader (MICR)
Wireless Input
n Can read text printed with magnetized ink
n Banking industry almost exclusively uses MICR for check
processing
n Handheld computer or device used to collect data
wirelessly at the location where transaction or event takes
place
n Data transferred later to desktop computer through docking
station
© Peter Locheck
2002
© Peter Lo 2002
number
bank
number
account
number
Input Devices for Physically
Challenged Users
check
145
amount
pointing
device for
those with
motor
disabilities
keyguard for limited
hand mobility
onscreen keyboard
146
New developments for physically
challenged users
n Gesture recognition
uComputer will detect human motions
uComputers with this capability have potential to
recognize sign language, read lips, track facial
movements, or follow eye gazes
n Implantation
uFor paralyzed or speech- impaired individuals
uDoctor will implant computerized device containing
transmitter into brain
uAs user thinks, transmitter will send signals to
computer
speech recognition
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148
37
What Is output?
Output Device
n Data that has been
processed into a
useful form, called
information
n Any hardware component that can convey
information to a user
graphics
text
monitor
speakers
printer
video
© Peter Lo 2002
audio
149
© Peter Lo 2002
Display Device
CRT Monitor
n Television-like
n Information on a display device sometimes is
called Soft Copy
n Large sealed, glass
screen
n Screen coated with tiny
dots of phosphor
material
n Pixel, or picture element,
is single point in
electronic image
n Three dots (red, blue,
and green) combine to
make up each pixel
150
cathode ray tube
CRT monitor
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151
© Peter Lo 2002
screen
152
38
Typical sizes for CRT monitors
n 15, 17, 19, 21, and
22 inch screen size
n Viewable size is
diagonal
measurement of
actual viewing area
provided by the
monitor
Liquid Crystal Display (LCD)
n Type of flat-panel display
n Uses liquid crystals between two sheets of
material to present information on screen
n Electric current passes through crystals, which
creates images on the screen
ize
ns
e
e
r
sc
e
siz
le
ab
w
vie
© Peter Lo 2002
153
© Peter Lo 2002
Some features of LCD screens
Web--enabled device
Web
n Lightweight and compact
n Consumes less than onethird of the power than
does a CRT monitor
n Ideal for notebook and
handheld computers
n Allows access to the Web or
e-mail
uCellular telephones
uPagers
n Many use monochrome LCD
displays to save battery power
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© Peter Lo 2002
154
156
39
Two technologies used for LCD
monitors
Electronic Book (e(e -book)
n Small, book-sized computer that uses an LCD screen
n Allows users to read, save, highlight, bookmark, and add
notes to online text
n Active-matrix display
uCan display high-quality color viewable from
all angles
n Passive-matrix display
uColor often not as bright
uImages best viewed when working directly in
front of display
n Download new book content
from Web
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158
Gas Plasma Monitor
Display resolution
n Flat-panel display uses layer of gas plasma
between two sheets of material
n Larger screen sizes and higher display quality than
LCD, but much more expensive
n Describes the sharpness and clarity of image
n The higher the resolution, the sharper the image and the
more that can display on the monitor
800 x 600
most common
1280 x 1024
maximum resolution
of most monitors
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159
2048 x 1536
maximum for
© Peter Lo 2002
high-end monitors
800 horizontal
pixels
600 vertical
pixels
Total of 480,000
pixels on screen
160
40
Dot Pitch
Refresh Rate
n Measure of the distance between pixels
n Sometimes called Pixel Pitch
n Smaller the distance between the pixels, the
sharper the image
n Use a monitor with a dot pitch of 0.29 millimeters
or lower to minimize eye fatigue
n Speed at which monitor redraws images on the
screen
n Should be fast enough to maintain a constant,
flicker-free image
n High-quality monitor will provide refresh rate of
at least 75 hertz
n Image on the screen redraws itself 75 times per
second
© Peter Lo 2002
© Peter Lo 2002
161
162
How does video travel from the
processor to a CRT monitor?
Video Card
n Converts digital output from computer into analog
video signal
n Controls how display device produces picture
n Also called Graphics Cardor Video Adapter
1: Processor sends digital data
to video card
2: Video card converts digital
data to analog signal
3: Analog signal sent via cable
to CRT monitor
4: CRT separates signal into
red, green, and blue signals
5: Electron guns fire color
signals to front of CRT
6: Image displays
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
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41
Bit Depth
n Number of bits a video
card uses to store
information about each
pixel
n Also called Color Depth
n Determines number
of colors a video card can
display
n Greater the number
of bits, better the resulting
image
Uses 8 bits to store
information about
each pixel
Can display 256
different colors
24-bit video
card
Uses 24 bits to
store information
about each pixel
© Peter Lo 2002
28 =
2x2x
2x2x
2x2x
2x2=
256
colors
8-bit video
card
What are video standards
n Video Electronics Standards Association (VESA)
develops video standards
224 =
16.7 million
colors
Can display 16.7
million colors
165
What are various video card
configurations?
© Peter Lo 2002
166
Electromagnetic Radiation (EMR)
n Magnetic field that travels at
speed of light
n Small amount produced by all CRT monitors
Sit at arm’s
length from
CRT
© Peter Lo 2002
167
© Peter Lo 2002
EMR is greatest
on sides and
back of CRT
monitor
LCD monitors
do not pose
this risk
168
42
ENERGY STAR® Program
Interactive TV
n Program to encourage manufacturers to create
energy-efficient devices that require little power
when not in use
n Monitors and devices meeting guidelines display
ENERGY STAR® label
n Two-way communications technology in which
users interact with television programming
n HDTV works directly with interactive TV
© Peter Lo 2002
169
Select a
movie from
a central
library of
movies
Play
games
Bank
Vote or
respond to
network
questionnaires
Shop
© Peter Lo 2002
Printer
Impact Printer
n Output device that produces text and graphics on paper
n Result is hard copy, or printout
n Two orientations
n Forms characters by striking a mechanism against ink
ribbon that physically contacts paper
n Ideal for printing multipart forms
portrait
portrait
orientation
orientation
© Peter Lo 2002
landscape
landscape
orientation
orientation
170
n Can withstand dusty environments, vibrations, and extreme
temperatures
171
© Peter Lo 2002
172
43
Dot--matrix Printer
Dot
How does dotdot-matrix printer work?
n Impact printer that produces printed images when tiny wire
pins on print head mechanism strike inked ribbon
n Most use continuous-form paper
n When ribbon presses against
paper, it creates dots that form
characters and graphics
n A higher number of pins (9 to
24) means printer prints more
dots per character, which results
in higher print quality
continuous-form paper
dots form characters
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© Peter Lo 2002
174
Line Printer
Non--impact printer
Non
n High-speed impact printer that
prints entire line at a time
n Speed measured by number of
lines per minute (lpm) it can print
n Band printer prints fully -formed
characters using a hammer
mechanism
n Forms characters and graphics on piece of paper
without actually striking paper
n Shuttle-matrix printer is highspeed printer that works more like
a dot-matrix printer
© Peter Lo 2002
ink-jet printer
175
© Peter Lo 2002
laser printer
thermal printer
176
44
Ink--jet Printer
Ink
Resolution of a printer
n Non-impact printer forms characters and graphics
by spraying tiny drops of liquid ink onto piece of
paper
n Most popular type of color printer for home use
n Sharpness and clarity of characters
n Measured by number of dots per inch (dpi)
printer can output
300
dpi
© Peter Lo 2002
177
How does an inkink -jet printer work?
1: Small
resistor heats
ink, causing
ink to boil and
form vapor
bubble
Print cartridge
firing
chamber
nozzle
print head
600
dpi
1,200 dpi
© Peter Lo 2002
178
Laser Printer
n High-speed, high-quality non-impact printer
n Prints text and graphics in very high -quality resolution,
ranging from 600 to 1,200 dpi
n Typically costs more than ink-jet printer, but is much faster
resistor
2: Vapor bubble forces ink
through nozzle
3: Ink drops onto paper
©
ink dot
bubble
4: As vapor bubble
collapses, fresh ink is
drawn
Peter
Lo 2002into firing chamber
nozzle
ink
179
© Peter Lo 2002
180
paper
45
How does a laser printer work?
1: Drum rotates as
paper is fed through
2: Mirror deflects
laser beam across
surface of drum
3: Laser beam
creates charge that
causes toner to
stick to drum
4: As drum rotates,
toner transfers
from drum to
paper
5: Rollers use heat
and pressure to fuse
toner to paper
Thermal Printer
n Generates images by pushing electrically heated
pins against heat-sensitive paper
n Ideal for small devices, such as adding machines
rotating mirror
drum
rollers
© Peter Lo 2002
181
Photo Printer
n Color printer that
produces photo
lab quality
pictures and
prints everyday
documents
© Peter Lo 2002
© Peter Lo 2002
182
Label Printer
n Small printer that prints on adhesive type material
that can be placed on a variety of items
n Most also print bar codes and e-stamps
Select image to print,
number of copies, and
size of print
183
© Peter Lo 2002
184
46
Portable Printer
Plotter
n Small, lightweight ink-jet or thermal printer that
allows mobile user to print from notebook or
handheld computer while traveling
n Sophisticated printer used to produce high-quality
drawings
n Large-format printer similar to plotter and is used to print
quality color prints
plotter
© Peter Lo 2002
185
© Peter Lo 2002
large-format printer
Audio Output Device
Voice Output
n Computer component that produces music, speech,
and other sounds
n Speakers and headsets are common devices
n Computer talks to you through speakers on
computer
RealPlayer
186
speakers
link to audio
broadcast
woofer
© Peter Lo 2002
187
© Peter Lo 2002
188
47
Internet Telephony
Data Projector
n Allows you to have a conversation over the Web,
just as if you were talking on the telephone
n Device that takes image from a computer screen
and projects it onto a larger screen
data projector
© Peter Lo 2002
189
© Peter Lo 2002
Facsimile (fax) Machine
Fax Modem
n Device that transmits and
receives documents over
telephone lines
n Modem that allows you to send and receive
electronic documents as faxes
190
fax machine
© Peter Lo 2002
191
externalfax
fax
external
modem
© Peter
Lo 2002
modem
internal
internal
fax
fax
modem
modem
card in
in
card
system
system
unit
192
unit
48
Multifunction Device (MFD)
Terminal
n Provides the functionality of a printer, scanner,
copy machine, and fax machine
n Device that performs both input and output
dumb
terminals
intelligent
terminals
specialpurpose
terminals
all in one
© Peter Lo 2002
Dumb Terminal
193
keyboard and monitor
© Peter Lo 2002
194
Intelligent Terminal
host computer
n Has a keyboard and
monitor, but no
processor or memory
n Connects to host
computer that performs
processing and then
sends output back
n Has monitor, keyboard, memory and
processor
n Similar to a PC in that it can
perform tasks independent of host
computer
n Programmable
intelligent terminal
© Peter Lo 2002
195
© Peter Lo 2002
196
49
Point--of
Point
of--Sale (POS) terminal
Automated Teller Machine (ATM)
n Records purchases at point
where purchase is made
n Output from POS terminals
serves as input to host
computer
n Self-service banking
machine that connects
to host computer
through telephone
network
POS terminal in a grocery store
scanner and keyboard are input
© Peter Lo 2002
197
© Peter Lo 2002
198
What is the Magnifier command?
Other output options for visually
impaired users?
n Windows Magnifier command enlarges text and
Magnifier
other items in window on screen
Magnifier
n Change Window’s settings such as increasing size or
changing color of text to make words easier to read
n Blind users can work with voice output
command
command
n Braille printer outputs information in Braille onto paper
Locationof
of
Location
mouse pointer
pointer
mouse
magnifiedat
at
magnified
topof
ofscreen
screen
top
Braille printer
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199
© Peter Lo 2002
200
50
References
n Computers in Your Future (Ch. 2)
n Introduction to Computing (Ch. 3)
n Discovering Computers World 2003 (Ch. 4 – 7)
© Peter Lo 2002
201
51
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