Transcript Computer Concepts 8

Chapter
4: Computer,
1:
File
Management,
Internet,
Virus
Chapter
2: Computer
Hardware
Protection,
Web,
and E-Mail
and Backup
Basics
1
Chapter 2 Preview
After this chapter, you should be able to:
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–
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Explain why most computers are digital
Describe the role of the ALU
List factors that affect performance
Explain RAM
Compare storage technologies
Chapter 2: Computer Hardware
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Chapter 2 Preview
After this chapter, you should be able to:
– Explain the factors that might help a
shopper decide whether to purchase a CRT,
LCD, or plasma monitor
– Compare and contrast the technologies and
applications for printers
– Describe computer’s expansion bus
– Explain hardware compatibility
considerations
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Chapter 2 Outline
• Section A
– Data Representation and Digital
Electronics
• Section B
– Microprocessors and Memory
• Section C
– Storage Devices
• Section D
– Input and Output Devices
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Chapter 2
Computer Hardware
Section A: Data Representation
and Digital Electronics
Computer Concepts 8th Edition
Parsons/Oja
Data Representation: How do
computers represent data
digitally?
• Data representation makes it possible to
convert letters, sounds, and images into a
form computers can use for processing
• A digital device works with discrete data,
such as the digits 1 and 0
• An analog device works with continuous
data
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Data Representation: How do
computers represent data
digitally?
• Computers are digital
• Just as a standard light switch is a
simpler technology than a dimmer, so
is digital when compared to analog
digital
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analog
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How does a computer
represent numbers?
• The binary number system (base 2)
uses only two digits 0, and 1
• The following table lists some decimal
numbers and their binary equivalent:
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How can a computer
represent words and letters
using bits?
• Character data is composed of letters,
symbols, and numerals that are not
used in arithmetic operations
• ASCII requires only 7 bits for each
character
• Extended ASCII uses 8 bits to
represent each character
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How can a computer
represent words and letters
using bits?
• EBCDIC is an alternative 8-bit used by
older IBM systems
• Unicode uses 16 bits and provides
codes for 65,000 characters
– Used for foreign language support
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How does a computer
convert sounds and pictures
into codes?
• Sounds and pictures must be
transformed into a format the computer
can understand
• A computer must digitize colors, notes,
and instrument sounds into 1s and 0s
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Quantifying Bits and Bytes:
How can I tell the difference
between bits and bytes?
• A bit is one binary digit (b)
–0
• A byte is 8 bits (B)
– 0010 0100
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Quantifying Bits and Bytes:
How can I tell the difference
between bits and bytes?
• Kilo- means a 1000, Mega- means
million, Giga -means billion
• Kilobit (Kb) is 1,024 bits
• Kilobyte (KB) is 1, 024 bytes
• Megabyte (MB) is 1,048,576 bytes
• Gigabyte (GB) is 1,073,741,824 bytes
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How does a computer store
and transport all these bits?
• Bits take the form of electrical pulses
that can travel over circuits
• This is almost the same way as
electricity flows over a wire when you
turn on a light switch
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What’s inside the
system unit?
• Desktop units are designed with
expectation that the home user may
add or update the equipment
• Small desktop and notebook
computers are not designed for users
to access all areas
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What’s inside the
system unit?
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What’s a computer chip?
• Most electronic components inside a
computer are integrated circuits
– Thin slices of silicon crystal packed with
microscopic circuit elements
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What’s a computer chip?
• Semiconducting materials are used to
fabricate a chip
• Types of chips:
– DIPs
– DIMMs
– PGAs
– SEC cartridge
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What’s a computer chip?
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How do chips fit together to
make a computer?
• The system board houses all
essential chips and provides
connecting circuitry between them
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How do chips fit together to
make a computer?
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Chapter 2
Computer Hardware
Section B: Microprocessors and Memory
Computer Concepts 8th Edition
Parsons/Oja
Microprocessor Basics:
What exactly is a
microprocessor?
• An integrated circuit designed to process
instructions
– CPU on a chip
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How does a microprocessor
work?
• The CPU has two parts
• ALU (arithmetic logic unit)
– Performs arithmetic operations
– Performs logical operations
– Uses registers to hold data being
processed
• The CPU’s control unit directs and
coordinates processing
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Can I replace my computer’s
microprocessor with a faster
one?
• Technically yes, but most computer
owners rarely do
• Reasons not to upgrade
– Cost
– Technical factors – speed
• Do research before you upgrade your
microprocessor
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Random Access Memory:
What is RAM?
• A temporary holding area for data,
application program instructions, and
the operating system
– As you type, characters are held in RAM
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How much RAM does my
computer need?
• RAM is primary storage (main memory)
– Measured in megabytes (MB) or gigabytes (GB)
• Today’s computers have between 128 MB
and 2 GB of RAM
• Depends on software you use
• You can purchase additional RAM
• A computer can use disk storage to simulate
RAM. This is called virtual memory
– Not as fast as RAM
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Do all computers use the
same type of RAM?
• No. RAM components vary in speed,
technology, and configuration
• Speed is measured in nanoseconds. 1
nanosecond (ns) is 1 billionth of a second
– It can also be expressed in MHz (millions of
cycles per second)
• SDRAM (Synchronous Dynamic RAM)
• RDRAM (Rambus Dynamic RAM)
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Read-Only Memory: How is
ROM different from RAM?
• Type of memory circuitry that holds the
computer’s startup routine
• Permanent and non-volatile
• Only way to change the instructions on
a ROM chip is to replace the chip
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CMOS Memory: Where does a
computer store its basic
hardware settings?
• A computer needs a semi-permanent
way of keeping boot data
• CMOS memory holds data but requires
very little power to retain its contents
– Retains important computer settings after
you turn the power off
– Can run by a battery on the system board
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Where does a computer store
its basic hardware settings?
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How do I get the best
computer for my money?
• Different buyers have different needs
• Assess your budget and think about
how you plan to use your computer
• Look at ads and visit online computer
stores
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Chapter 2
Computer Hardware
Section C: Storage Devices
Computer Concepts 8th Edition
Parsons/Oja
Storage Basics: What are the
basic components of a data
storage system?
• A storage medium is the disk, tape,
CD, DVD, paper or other substance
that contains data
• A storage device is the mechanical
apparatus that records and retrieves
data from a storage medium
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How does magnetic storage
work?
• Stores data by magnetizing
microscopic particles on the disk or
tape surface
• Read-write head - mechanism in the
disk drive that reads and writes
magnetized particles that represent
data
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How does magnetic storage
work?
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How does optical storage
work?
• Stores data as microscopic light spots
(lands) and dark spots (pits) on the
disk surface
• Less susceptible to environmental
damage than data recorded on
magnetic media
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How does optical storage
work?
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How does solid state storage
work?
• Stores data in a non-volatile, erasable, lowpower chip
• Some solid state storage requires a device
called a card reader to transfer data to or from
a computer
• Provides faster access to data than magnetic or
optical storage technology because it includes
no moving parts
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Can I add storage devices to
my computer?
• Devices can be added into empty drive
bays
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What is floppy disk technology?
• A floppy disk is a round piece of flexible
mylar plastic covered with a thin layer of
magnetic oxide and sealed inside a
protective casing
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How much data can a HD DS
disk and a Zip disk hold?
• HD DS 3½” diskettes have capacity of
1.44 MB
• Zip disks come in 100 MB, 250 MB, and
750 MB versions
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What are the advantages and
disadvantages of HD DS
floppy disks?
• Major advantage – portability
• Major disadvantage – not a particularly
speedy device and limited storage
capacity
• Slowly being replaced by solid state
technology
• Today most software vendors use CDROM or DVD-ROM disks instead
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How can ZIP disks store more
data than standard floppy
disk?
• Disk density - closeness and size of
magnetic particles on the disk’s surface
• Zip disks store data at a higher density
than a standard 3½” floppy disk
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How does a hard disk work?
• Hard disk platter - a flat, rigid disk
made of aluminum or glass and coated
with magnetic iron oxide particles
– Density far exceeds floppy disk
• Hard disk - one or more platters and
their associated read-write heads
– Preferred type of main storage
• Miniature hard drives store 20 to 40 GB
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How does a hard disk work?
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What’s the downside of hard
disk storage?
• Head crash - when a read-write head
runs into a dust particle or other
contaminant on the disk
– Head crash damages some data on disk
– Triggered by jarring the hard disk while in
use
– Not limited to hard disks
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Tape Storage: What’s the
purpose of a tape drive?
• Tape backup - copy of data on hard
disk stored on magnetic tape
• Relatively inexpensive
• Primarily used on business computers
• Not suitable for everyday storage tasks
• Sequential-access storage medium
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CD and DVD technology: Is
there a difference between
CD and DVD technology?
• CD
– Holds up to 80 minutes of music or 700
MB of data
• DVD
– Holds about 4.7 GB of data
– A double layer DVD has two recordable
layers on the same side and can store 8.5
GB of data
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How do CD and DVD drives
work?
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How do CD and DVD drives
work?
• Recordable technology uses a laser
to change the color in a dye layer
sandwiched beneath the clear plastic
disk surface
• Rewritable technology uses “phase
change” technology to alter a crystal
structure on the disk surface
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Can I use a single drive to work
with any CD or DVD media?
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Are rewritable CD or DVD
drives an acceptable
replacement for a hard disk?
• It is slower than hard disk access
• Not yet a suitable replacement
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Is my computer DVD drive the
same as the one connected to
my TV?
• Not exactly
– Movie files are still very large
– Television DVD drives include MPEG
decoding circuitry
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Solid State Storage: When
would I use solid state
storage?
• Portable, provides fast access to data
and uses very little power
– USB flash drive
– CompactFlash card
– MMC
– SecureDigital
– SmartMedia
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Chapter 2
Computer Hardware
Section D: Input and Output Devices
Computer Concepts 8th Edition
Parsons/Oja
Basic Input Devices: What
devices can I use to get data
into a computer?
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What are my options for
display devices?
• CRT (cathode ray tube)
• LCD (liquid crystal display)
– LCDs are clearer, have low radiation
emission, are portable, and compact
– LCDs are also more expensive than CRTs
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What are my options for
display devices?
• Plasma screen technology
– Lightweight, compact, and more expensive
than CRT monitors
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How does an ink jet printer
work?
• Nozzle-like print head that sprays ink onto
paper to form characters and graphics
• Most ink jet printers use CMYK color
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How do laser printers
compare to ink jet printers?
• A laser printer paints dots of light on a
light-sensitive drum
– Higher quality than ink jet
– More expensive to buy than ink jet
– Less expensive to operate than ink jet
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How do laser printers
compare to ink jet printers?
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What is a dot matrix printer?
• Produce characters and graphics by
using a grid of fine wires
– Introduced in 1970s
– Low quality output
– Used for “back-office” applications that
demand low operating cost and
dependability
– Can print multipart carbon forms
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What is a dot matrix printer?
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What other printer
technologies are available?
• Thermal transfer printer
– Uses page-sized ribbons coated with wax
– Print head consists of heating elements to
melt the wax
• Dye sublimation printer
– Similar to wax, but page-sized ribbon
contains dye
– Print heads diffuse the dye
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Printers: What features
should I look for in a printer?
• Resolution
– Measured in dpi (dots per inch)
• Print speed
– Measured either by pages per minute
(ppm) or characters per second (cps)
• Color takes longer than black and white
• Text prints faster than graphics
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What features should I look
for in a printer?
• Duty cycle - indication of the number of
pages a printer can be expected to print per
month
• Indicates maintenance costs
• Operating costs
– Printers require ongoing costs including ribbons,
ink cartridges, and toner
– Per copy cost is the cost of printing a page with
an average amount of text, graphics, and color
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What features should I look
for in a printer?
• Duplex capability
– A printer with duplex capability can print on both
sides of the paper
• Memory
– A computer sends data for a printout to the
printer along with a set of instructions on how to
print the data
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Installing Peripheral Devices:
Is it difficult to install a new
peripheral device?
• Internal devices
– Tools required
• Screwdriver
• Directions
– Before installing
• Unplug the computer
• Ground yourself
– Installing
• Follow the directions
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What’s an expansion slot?
• Expansion slot - long, narrow socket on the
system board into which you can plug an
expansion card
• Expansion card - small circuit board that
provides computer with ability to control
storage, input or output device
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What’s an expansion slot?
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What’s an expansion slot?
• ISA (Industry Standard Architecture)
– Used today only for some modems and other
relatively slow devices
• PCI (Peripheral Component Interconnect)
– Offers fast transfer speeds and a 32-bit or 64-bit
data bus
• AGP (Accelerated Graphics Port)
– Provides a high-speed data pathway primarily
used for graphics cards
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Do notebook computers
contain expansion slots?
• Equipped with a special type of
external slot called a PCMCIA slot
• Typically a notebook only has one slot,
but the slot can hold more than one PC
card (PCMCIA expansion cards)
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What is an expansion port?
• Used to connect a peripheral device
• Expansion port - any connector that
passes data in and out of a computer
or peripheral device
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What is an expansion port?
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How do I know which cable
to use?
Serial
DB-9
Parallel
DB-25M
USB
SCSI
C-50F
IEEE 13394
VGA
HDB-15
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Conclusion
You should now be able to:
– Explain why most computers are digital
– Describe the role of the ALU
– List factors that affect performance
– Explain RAM
– Compare storage technologies
– Describe computer’s expansion bus
– Explain hardware compatibility
considerations
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