Notes

1. Chapter 2: Storage (Part 1)
F1031 COMPUTER HARDWARE
Jabatan Teknologi Maklumat
& Komunikasi (JTMK)

2. Lecture Outcomes
Discuss the various types of items that
users store on computer media
Discuss the various types of items that
users store on computer media
Differentiate between storage devices
and storage media
Differentiate between storage devices
and storage media
Describe the characteristics of
a floppy disk drive
Describe the characteristics of
a floppy disk drive
Identify the uses of Zip disksIdentify the uses of Zip disks
Describe the characteristics of
a hard disk
Describe the characteristics of
a hard disk
Identify the advantages of using
an Internet hard drive
Identify the advantages of using
an Internet hard drive
Describe the characteristics of
CDs and DVDs
Describe the characteristics of
CDs and DVDs
Differentiate among CD-ROMs,
CD-RWs, DVD-ROMs, and DVD+RWs
Differentiate among CD-ROMs,
CD-RWs, DVD-ROMs, and DVD+RWs
Identify the uses of tapeIdentify the uses of tape
Discuss PC Cards and the various types
of miniature storage media
Discuss PC Cards and the various types
of miniature storage media
Identify uses of microfilm and
microfiche
Identify uses of microfilm and
microfiche

3. Storage
What is storage?
 Holds data, instructions, and information for future use
 Storage medium is physical material used for storage
 Also called secondary
storage

4. Storage
What is capacity?
Kilobyte (KB) 1 thousand
Megabyte (MB) 1 million
Gigabyte (GB) 1 billion
Terabyte (TB) 1 trillion
Petabyte (PB) 1 quadrillion
 Number of bytes (characters) a storage medium can hold
Exabyte (EB) 1 quintillion
Zettabyte (ZB) 1 sextillion
Yottabyte (YB) 1 septillion

5. Storage Medium
(floppy disks, Zip disks,
hard disks, CDs)
Storage
How does volatility compare?
Nonvolatile
 Storage medium is nonvolatile—contents retained when
power is off
ContentsContents
retainedretained
ContentsContents
available to useravailable to user
Memory
(most RAM)
(chips on motherboard)
Screen Display
ON OFF
Volatile
DisplayDisplay
disappearsdisappears
Data andData and
instructionsinstructions
available to useravailable to user
DisplayDisplay
appearsappears
Data andData and
instructions erasedinstructions erased
 Memory is volatile—holds data and instructions temporarily

6. WritingWriting
Process of transferringProcess of transferring
items from memoryitems from memory
to storage mediato storage media
WritingWriting
Process of transferringProcess of transferring
items from memoryitems from memory
to storage mediato storage media
Storage
What is a storage device?
ReadingReading
Process of transferringProcess of transferring
items from storageitems from storage
media to memorymedia to memory
ReadingReading
Process of transferringProcess of transferring
items from storageitems from storage
media to memorymedia to memory
Hardware thatHardware that
records andrecords and
retrieves itemsretrieves items
to and fromto and from
storage mediastorage media
Functions as source
of input
Creates output

7. Floppy Disk Small files to be transported
Secondary Storage
Primary Storage
Hard Disk
CDs and DVDs
Miniature Storage Media
Tape
Items waiting to be interpreted
and executed by the processor
Operating system, application
software, user data and information
Software, backups, movies, music
Digital pictures or small files to
be transported
Backups
Memory (most RAM)
Stores …
Storage
What is access time?
 Time it takes storage device to locate item on storage medium
 Time required to deliver item from memory to processor
faster
transfer
rates
slower
transfer
rates

8. Floppy Disks
What is a floppy disk?
 Portable, inexpensive storage
medium (also called diskette)
Thin, circular, flexible film enclosed
in 3.5” wide plastic shell
shutter
shell
liner
magnetic
coating
flexible thin film
metal hub

9. Floppy Disks
What is a floppy disk drive?
Floppy disk drive built into
a desktop computer
External floppy disk drive attaches to
a computer with a cable
 Also called secondary storage
 One floppy drive, named drive A
 If two floppy drives, second
designated as drive B
 Device that reads from and
writes to floppy disk

10. Floppy Disks
How does a floppy disk drive work?
Step 1. When you insert the floppy disk into
drive, shutter moves to the side to expose the
recording surface on disk.
Step 2. When you initiate a disk
access, circuit board on drive that
contains electronics sends signals to
control movement of read/write heads
until they barely touch surface (film)
inside floppy disk’s shell.
Step 3. For write instructions,
circuit board verifies whether or
not disk can be written on.
Step 4. Motor spins a
shaft, which causes
surface inside floppy
disk’s shell to spin.
Step 5. Motor
positions read/write
heads over correct
location on recording
surface of disk.
Step 6. Read/write
heads read data from
and write data on
floppy disk.

11. Floppy Disks
What are tracks and sectors?
Track
is narrow
recording band
that forms full
circle on disk
Sector
stores up to
512 bytes
of data
Formatting prepares disk for use and marks bad sectors as unusable

12. Floppy Disks
How do you compute a disk’s storage capacity?
 Multiply number of sides, number of tracks, number of sectors per
track, and number of bytes per sector
 For high-density disk: 2 sides × 80 tracks × 18 sectors per track × 512
bytes per sector = 1,474,560 bytes
Characteristics of a
3.5-inch High-Density
Floppy Disk
Capacity: 1.44 MB
Sides: 2
Tracks: 80
Sectors per track: 512
Sectors per disk: 2880

13. Floppy Disks
Never open the
shutter and
touch the disk’s
surface
Never open the
shutter and
touch the disk’s
surface
How do you care for a floppy?
Avoid exposure
to heat and
cold
Avoid exposure
to heat and
cold
Avoid exposure
to magnetic
fields
Avoid exposure
to magnetic
fields Avoid exposure
to contaminants
such as dust,
smoke, or
salt air
Avoid exposure
to contaminants
such as dust,
smoke, or
salt air
Keep disks in
a storage tray
when not
using them
Keep disks in
a storage tray
when not
using them
 Proper care helps maximize disk’s life
 Floppy disk can last at least seven years

14. Floppy Disks
What is a write-protect notch?
 Small opening with a cover that you slide
 Protects floppy disk from being erased accidentally
hole on this
side means
disk is high
density
hole on this
side means
disk is high
density
write-protected
not write-protected
notch closed
means you
can write on
the disk
notch closed
means you
can write on
the disk
notch open
means you
cannot write
on the disk
notch open
means you
cannot write
on the disk

15. External
Zip drive
Zip®
Disks
What is a Zip disk?
 Magnetic medium that stores 100 MB
to 750 MB of data
 Zip disks require a Zip drivec—chigh
capacity drive that reads from and
writes on a Zip disk
 Used to back up and to transfer files
 Backup is duplicate of file, program, or disk
in case original is lost
c
Zip disk

16. Hard Disks
What is a hard disk?
hard disk installed
in system unit
 High-capacity storage
 Consists of several
inflexible, circular
platters that store items
electronically
 Components enclosed in
airtight, sealed case for
protection

17. Hard Disks
What are characteristics of a hard disk?
Sample Hard Disk Characteristics
Advertised capacity 120 GB
Platters 3
Read/write heads 6
Cylinders 16,383
Bytes per second 512
Sectors per track 63
Sectors per drive 234,441,648
Revolutions per minute 7,200
Transfer rate 133 MB per second
Access time 8.9 ms
actual
disk
capacity

18. Hard Disks
How does a hard disk work?
Step 1.
Circuit board controls
movement of head actuator
and a small motor.
Step 2.
Small motor spins
platters while
computer is running.
Step 3.
When software requests a
disk access, read/write
heads determine current
or new location of data.
Step 4.
Head actuator positions
read/write head arms over
correct location on platters
to read or write data.

19. Hard Disks
What is a cylinder?
 Vertical section of
track through all
platters
 Single movement
of read/write head
arms accesses all
platters
in cylinder
platter
read/write
head
platter
sides
cylinder
track
sector

20. Hard Disks
What is a head crash?
clearance
read/write head
platter
hair
dust
smoke
 Spinning creates cushion of air that floats read/write head above
platter
 Occurs when read/write head touches platter surface
 A smoke particle, dust particle, or human hair could render drive unusable
 Clearance between head and platter is approximately two-millionths of an inch

21. hard disk
Hard Disks
What is a disk cache?
 Portion of
memory that
processor uses
to store
frequently
accessed items
second request
for data—to hard disk
disk cache
first request
for data—to disk cache
processor

22. Hard Disks
What are external hard disks and removable hard disks?
External hard disk—freestanding
hard disk that connects to system unit
Removable hard disk—hard disk
that you insert and remove
from hard disk drive
 Used to back up or transfer files

23. Hard Disks
What is a disk controller?
EIDEEIDE (EEnhancednhanced IIntegratedntegrated DDriverive
EElectronics) controller supports fourlectronics) controller supports four
hard disks, provides connections forhard disks, provides connections for
CD and DVD drivesCD and DVD drives
Chip and circuits thatChip and circuits that
control transfer ofcontrol transfer of
items from diskitems from disk
SCSISCSI
((SSmallmall CComputeromputer SSystemystem IInterface)nterface)
controller supports up to fifteencontroller supports up to fifteen
devices including hard disks, CDdevices including hard disks, CD
and DVD drives, tape drives, printers,and DVD drives, tape drives, printers,
scanners, network cardsscanners, network cards

24. Hard Disks
What is an Internet hard drive?
 Others can be authorized
to access your data
 Service on Web that provides storage for
minimal monthly fee
 Files can be accessed from
any computer with Web
access
 Large files can be downloaded
instantaneously

25. Push the same button
to close the tray.
CDs and DVDs
What are CDs and DVDs?
 Most PCs include CD
or DVD drive, most
play audio CDs
 Flat, round, portable
metal discs made of
metal, plastic, and
lacquer
 Can be read only or
read/write
Insert the disc,
label side up.
Push the button to
slide out the tray.

26. CDs and DVDs
How does a laser read data on a CD or DVD?
laser
diode
laser
diode
prism prism
light-
sensing
diode
light-
sensing
diode
0 1
lens lenspit land
disc label
Step 1.
Laser diode
shines a light
beam toward
disc.
Step 2.
If light strikes
a pit, it scatters.
If light strikes a
land, it is
reflected back
toward diode.
Step 3.
Reflected light is
deflected to a
light-sensing diode,
which sends digital
signals of 1 to
computer. Absence
of reflected light is
read as digital
signal of 0.

27. CDs and DVDs
How is data stored on a CD or DVD?
 Typically stored in
single track
 Track divided
into evenly
sized sectors
that store
items
single track
spirals to edge
of disc
disc sectors

28. CDs and DVDs
How should you care for a CD or DVD?
Do store the
disc in a jewel
box when
not in use
Do hold a disc
by its edges
Do not
eat, smoke, or
drink near
a disc
Do not stack discs
Do not expose
the disc to
excessive
heat or
sunlight
Do not touch
the underside
of the disc

29. CDs and DVDs
What is a CD-ROM?
 Compact disc read-
only memory
 Cannot erase or
modify contents
 Typically holds
650 MB to 1 GB
 Commonly used
to distribute
multimedia and
complex
software

30. CDs and DVDs
What is the data transfer rate of a CD-ROM drive?
75X
Ranges from
48X to 75X
or faster
7575 ×× 150 KBps = 11,250 KBps150 KBps = 11,250 KBps
or 12.25 MBpsor 12.25 MBps
75X is 150 KBps75X is 150 KBps
(KB per second)(KB per second)
48X:48X:
4848 ×× 150 KBps = 7,200 KBps150 KBps = 7,200 KBps
or 7.2 MBpsor 7.2 MBps

31. CDs and DVDs
What is a Picture CD?
Film developers
offer
Picture CD
service
Can be
modified
using photo
editing software
Stores digital
versions of
roll of film
Step 3.
At home, print images
from Picture CD on
your ink-jet photo printer.
At a store, print images to
Picture CD at kiosk.
Step 1.
Drop off film to
be developed.
Mark the Picture
CD box on the
film-processing
envelope.
Step 2.
When you pick up
prints and negatives, a
Picture CD contains
digital images of each
photograph.

32. CDs and DVDs
What are CD-Rs and CD-RWs? Must have
CD recorder
or CD-R drive
Cannot erase
disc’s contents
CD-R (compact disc-readable)
—cdisc you can write on once
CD-RW (compact disc-rewritable)
—ceerasable disc you can write on
multiple times
Must have
CD-RW software
and CD-RW drive

33. How is an audio CD created?
Step 5.
User listens
to song on
a personal
computer or
removes CD and
listens to song on
a portable CD
player.
Step 2.
Song is stored on audio CD and
purchased
by user.
Step 1.
Artist composes a song.
Step 3.
User inserts audio CD into
CD drive, plays song, and
rips desired tracks onto
hard disk.
Step 4.
User copies file to a
CD-RW disc.
CDs and DVDs
 From a purchased CD. . .

34. CDs and DVDs
Step 3.
User pays for and
downloads song as
audio file onto a
hard disk.
Step 2.
Song is compressed and
stored on the Internet.
How is an audio CD created?
 From the Internet. . .
Step 5.
User listens
to song on
a personal
computer or
removes CD and
listens to song on
a portable CD
player.
Step 1.
Artist composes a song.
Step 4.
User copies file to a
CD-RW disc.

35. CDs and DVDs
What is a DVD-ROM (digital versatile
disc-ROM or digital video disc-ROM)?
DVD
DVD drive
 High capacity disc capable of
storing 4.7 GB to 17 GB
 Must have DVD-ROM drive or
DVD player to read DVD-ROM
 Stores databases, music,
complex software, and movies

36. CDs and DVDs
How does a DVD-ROM store data?
DVD-ROM Storage Capacities
Sides Layers Storage Capacity
1 1 47 GB
1 1 8.5 GB
2 1 9.4 GB
2 2 17 GB
 Two layers of pits are used, lower layer is
semitransparent so laser can read through
 Some are double-sided
 DVD+RW is a rewritable DVD

37. Tape
What is tape?
 Magnetically coated plastic ribbon
capable of storing large amounts
of data at low cost
 Primarily used for backup

38. Tape
How is data stored on a tape?
 Sequential access
Digital audio tape DAT 2 GB to 240 GB
(also called digital data storage) (also called DDS)
Digital linear tape DLT 20 GB to 229 GB
Linear tape-open LTO 100 GB to 200 GB
Quarter-inch cartridge QIC 40 MB to 50 GB
Travan TR 8 GB to 50 GB
Popular Types of Tape
Name Abbreviation Storage Capacity
 Unlike direct access — used on floppy disks, Zip disks,
hard disks, CDs, and DVDs — which can locate
particular item immediately
 Reads and writes data consecutively, like music tape

39. PC Cards
What is a PC Card?
PC Cards
Category Thickness Use
Type I 3.3 mm RAM, SRAM, flash
memory
Type II 5.0 mm Modem, LAN, SCSI,
sound, TV turner, hard
disk, or other storage
Type III 10.5 mm Rotating storage such
as a hard disk
 Adds capabilities to computer
 Credit-card-sized device commonly
used in notebook computers

40. Miniature Mobile Storage Media
What is miniature mobile storage media?
 Storage for small mobile devices

41. Miniature Mobile Storage Media
What are common types of miniature mobile storage media?
Smart Media
xD Picture Card
CompactFlash Secure Digital
Memory Stick Microdrive

42. Miniature Mobile Storage Media
What is a card reader?
 Reads information stored on miniature mobile storage media
 Type of card determines type of card reader needed

43. Miniature Mobile Storage Media
What is a smart card?
 Stores data on microprocessor
embedded in small card
 Input, process, output, and
storage capabilities

44. Miniature Mobile Storage Media
What is e-money (electronic money)?
Sometimes placedSometimes placed
on smart cardon smart card
Means of paying forMeans of paying for
goods and servicesgoods and services
over the Internetover the Internet
Also called digital cashAlso called digital cash
Bank issues uniqueBank issues unique
digital cash numbersdigital cash numbers
that represent amountthat represent amount
of moneyof money
Money is withdrawnMoney is withdrawn
from your bankfrom your bank
accountaccount

45. Microfilm and Microfiche
What are microfilm and microfiche?
Images recorded usingImages recorded using
computer output microfilm recordercomputer output microfilm recorder
Store microscopic images ofStore microscopic images of
documents on roll or sheet of filmdocuments on roll or sheet of film
Microfilm — 100- to
215-foot roll of film
Microfiche — small sheet
of film, usually 4” × 6”

46. Microfilm and Microfiche
How do life expectancies of various media compare?
Media Life Expectancies
Magnetic disks 3 to 5 years 20 to 30 years
CDs and DVDs discs 5 to 10 years 50 to 100 years
Microfilm 100 years 500 years
Media Type Guaranteed Life Potential Life
Expectancy Expectancy
 Microfilm and microfiche have longest life of any storage media

47. The System Unit
What is the system unit?
 Case that contains electronic
components of the computer used
to process data
 Sometimes called
the chassis

48. The System Unit
What are common components inside the system unit?
 Memory
 Adapter cards
 Sound card
 Modem card
 Video card
 Network card
 Ports
 Drive bays
 Power supply
power supply
ports
drive bays
processor
memory
sound card
video card
modem card
network card
 Processor

49. The System Unit
What is the motherboard?
 Main circuit
board in system
unit
 Contains adapter
cards, processor
chips, and
memory chips
 Also called
system board
processor chip
adapter cards
memory chips
memory slots
motherboard
Expansion
slots for
adapter cards

50. The System Unit
What is a chip?
dual inline
packages (DIP)
holds memory
chips
pin grid
array (PGA)
package
holds processor
chips
 Small piece of semi-conducting
material on which integrated
circuits are etched
 Integrated circuits contain
many microscopic pathways
capable of carrying electrical
current
 Chips are packaged so they can
be attached to a circuit board

51. Expansion Slots and Adapter Cards
What is an adapter card?
Types of Adapter Cards
 Enhances system unit or
provides connections to
external devices called
peripherals
 Also called an expansion card

52. Expansion Slots and Adapter Cards
What is an expansion slot?
 An opening, or socket,
on the motherboard
that can hold an
adapter card
 With Plug and Play,
the computer
automatically
configures cards
and other devices
as you install them

53. ProcessorProcessor
ControlControl
UnitUnit
ArithmeticArithmetic
Logic Unit (ALU)Logic Unit (ALU)
ArithmeticArithmetic
Logic Unit (ALU)Logic Unit (ALU)
Processor
What is the central processing unit (CPU)?
InputInput
DevicesDevices
StorageStorage
DevicesDevices
OutputOutput
DevicesDevices
 Interprets and carries
out basic instructions
that operate a computer
MemoryMemoryDataData InformationInformation
InstructionsInstructions
DataData
InformatioInformatio
nn
InstructionsInstructions
DataData
InformatioInformatio
nn
ControlControl
UnitUnit
 Control unit directs and
coordinates operations in
computer
 Arithmetic logic unit
(ALU) performs
arithmetic, comparison,
and logical operations
 Also called the processor

54. Processor
Control Unit
Memory
ALU
Processor
What is a machine cycle?
Step 1. Fetch
Obtain program instruction
or data item from memory
Step 2.
Decode
Translate
instruction into
commands
Step 4. Store
Write result to memory
Step 3. Execute
Carry out command
 Four operations of the CPU comprise a machine cycle

55. Processor
What is pipelining?
 CPU begins fetching second instruction before
completing machine cycle for first instruction
 Results in faster processing

56. Stores locationStores location
from where instructionfrom where instruction
was fetchedwas fetched
Processor
StoresStores
instruction while it isinstruction while it is
being decodedbeing decoded
What is a register?
Stores dataStores data
while ALUwhile ALU
computes itcomputes it
Stores resultsStores results
of calculationof calculation
 Temporary high-speed storage area that holds
data and instructions

57. Processor
What is the system clock?
Each tickEach tick
is ais a
clock cycleclock cycle
Pace of systemPace of system
clock isclock is clock speedclock speed
Most clock speeds areMost clock speeds are
in the gigahertz (GHz)in the gigahertz (GHz)
range (1 GHz = onerange (1 GHz = one
billion ticks of systembillion ticks of system
clock per second)clock per second)
Processor speed canProcessor speed can
also be measured inalso be measured in
mmillions ofillions of iinstructionsnstructions
pperer ssecondecond (MIPS)(MIPS)
 Controls timing of all computer operations
 Generates regular electronic pulses, or ticks, that set
operating pace of components of system unit

58. Processor
How do personal computer processors compare?
Comparison of Widely Used
Personal Computer Processors
Name Date Clock
Introduced Speed
Itanium 2 2002 1.3–1.5 GHZ
Xeon 2001 1.4–3.06 GHZ
Itanium 2001 733–800 MHZ
Pentium 4 2000 1.4–3.2 GHZ
Pentium III Xeon 1999 500–900 MHZ
Pentium III 1999 400 MHZ–1.4 GHZ
Celeron 1998 266 MHZ–2.6 GHZ
Operon 2003 2–2.4 GHZ
Athlon MP 2002 1.53–2.25 GHZ
Athlon XP 2001 1.33–2.26 GHZ
Athlon 1999 500 MHZ–1.4 GHZ
™

59. Processor
Which processor should you select?
 The faster the processor, the more expensive the computer
Celeron
Itanium or Xeon
Pentium family
1.3 GHz and up
3.0 GHz and up
2.4 GHz to 3.0 GHz
Up to 2.4 GHz
2.2 GHz and up
Intel Processor Desired Clock Speed

60. Chip-for chip upgradeChip-for chip upgrade
replace the chipreplace the chip
Processor
What are the types of processor upgrades?
Piggyback upgradePiggyback upgrade
stack new chip on top of old onestack new chip on top of old one
Daughterboard upgradeDaughterboard upgrade
chip is on adapter card that plugs into motherboardchip is on adapter card that plugs into motherboard

61. Processor
What is a zero-insertion force (ZIF) socket?
Step 2.
Insert the chip.
Step 1.
Lift the lever on the socket.
lever
Step 3.
Push the lever down.
lever
 Allows you to install and remove chips with no force

62. Processor
What are heat sinks and heat pipes?
 Heat sink—component
with fins that cools
processor
heat sink fan
heat sink
 Heat pipee—smaller
device for notebook
computers

63. Processor
What is a coprocessor?
Chip that assists processor in
performing specific tasks
Chip that assists processor in
performing specific tasks
One type is a floating-point coprocessorfloating-point coprocessor, also
known as a math or numeric coprocessor
One type is a floating-point coprocessorfloating-point coprocessor, also
known as a math or numeric coprocessor

64. Processor
What is parallel processing?
Control ProcessorControl Processor
Processor 1Processor 1
MemoryMemory
Processor 2Processor 2
MemoryMemory
Processor 3Processor 3
MemoryMemory
Processor 4Processor 4
MemoryMemory
Results combined
 Using multiple
processors
simultaneously to
execute a
program faster
 Requires special
software to divide
problem and
bring results
together

65. Memory
What is memory?
 Electronic components that
store instructions, data, and
results
 Consists of one or
more chips on
motherboard or
other circuit board
 Each byte stored
in unique location
called an address,
similar to seats
on a passenger train
Seat #2B4 Seat #2B3

66. Memory
How is memory measured?
Term Abbreviation Approximate Size
Kilobyte KB or K 1 thousand bytes
Megabyte MB 1 million bytes
Gigabyte GB 1 billion bytes
Terabyte TB 1 trillion bytes
 By number of bytes available for storage

67. Memory
What is random access memory (RAM)?
The more RAM aThe more RAM a
computer has, thecomputer has, the
faster it respondsfaster it responds
Also calledAlso called
main memorymain memory
oror primaryprimary
storagestorage
Most RAM isMost RAM is
volatilevolatile, it is lost, it is lost
when computer’swhen computer’s
power ispower is
turned offturned off
Memory chips that can beMemory chips that can be
read from and writtenread from and written
to by processorto by processor

68. Memory
How do program instructions transfer in and out of RAM?
Step 1. When you start the computer, certain
operating system files are loaded into RAM from
the hard disk. The operating system displays the
user interface on the screen.
Operating systemOperating system
instructionsinstructions
Web browserWeb browser
instructionsinstructions
Word processingWord processing
programprogram
instructionsinstructions
Operating systemOperating system
interfaceinterface
Web browserWeb browser
windowwindow
Word processingWord processing
program windowprogram window
RAM
RAM
Web browser programWeb browser program
instructions areinstructions are
removed from RAMremoved from RAM
Web browserWeb browser
window no longer iswindow no longer is
displayed ondisplayed on
desktopdesktop
Step 2. When you start a Web browser, the
program’s instructions are loaded into RAM from
the hard disk. The Web browser window is
displayed on the screen.
Step 3. When you start a word processing
program, the program’s instructions are loaded
into RAM from the hard disk. The word
processing program, along with the Web Browser
and certain operating system instructions are in
RAM. The word processing program window is
displayed on the screen.
Step 4. When you quit a program, such as the
Web browser, its program instructions are
removed from RAM. The Web browser no longer
is displayed on the screen.

69. FasterFaster
variationsvariations
of DRAM areof DRAM are
SDRAMSDRAM andand
RDRAMRDRAM
Used forUsed for
specialspecial
applicationsapplications
such assuch as
cachecache
MostMost
commoncommon
typetype
Faster andFaster and
more reliablemore reliable
than DRAMthan DRAM
chipschips
Memory
What are two basic types of RAM chips?
((
DynamicDynamic
RAMRAM
(DRAM)(DRAM)
Future: Magnetoresistive RAM (MRAM)
StaticStatic
RAMRAM
(SRAM)(SRAM)

70. Memory
Where does memory reside?
 Resides on small circuit
board called memory
module
 Memory slots on
motherboard hold memory
modules
memory chip memory slot
dual inline memory module

71. Memory
How much RAM does an application require?
 Software package
typically indicates
RAM requirements
 For optimal
performance, you
need more than
minimum specifications
System Requirements
Windows®
XP Home Edition/Professional
• Intel Pentium processor at 233MHZ or higher
• AMD K6 (Athlon Duron Family processor at 233MHZ or higher
• 64 MB of RAM

72. Memory
How much RAM do you need?
 Depends on type of applications you intend to run
on your computer
RAM
Use
128 to 256 MB 256 to 1 GB 1 GB and up
• Home and business
users managing
personal finance
• Using standard
application software
such as word processing
• Using educational
or entertainment
CD-ROMs
• Communicating with
others on the Web
• Users requiring more advanced
multimedia capabilities
• Running number-intensive
accounting, financial, or
spreadsheet programs
• Using voice recognition
• Working with videos, music, and
digital imaging
• Creating Web sites
• Participating in video conferences
• Playing Internet games
• Power users creating
professional Web sites
• Running sophisticated
CAD, 3D design, or
other graphics-intensive
software

73. Memory
What is cache?
 L1 cache built into processor
 L2 cache slower but has larger capacity
 L2 advanced transfer cache is faster,
built directly on processor chip
 L3 cache is separate from processor
chip on motherboard (L3 is only
on computers that use L2 advanced
transfer cache)
 Helps speed computer processes by storing frequently used
instructions and data
 Also called memory cache

74. Memory
What is read-only memory (ROM)?
Memory chips that storeMemory chips that store
permanent datapermanent data
and instructionsand instructions
Nonvolatile memoryNonvolatile memory, it is not, it is not
lost when computer’slost when computer’s
power is turned offpower is turned off
Three types:Three types:
FirmwareFirmware——
Manufactured withManufactured with
permanently writtenpermanently written
data, instructions,data, instructions,
or informationor information
EEPROMEEPROM
((eelectricallylectrically
eerasablerasable pprogrammablerogrammable
rread-ead-oonlynly mmemory)—emory)—
Type of PROMType of PROM
containing microcodecontaining microcode
programmerprogrammer
can erasecan erase
PROMPROM
((pprogrammablerogrammable
rread-ead-oonlynly
mmemory)—emory)—
Blank ROMBlank ROM
chip onto whichchip onto which
a programmera programmer
can write permanentlycan write permanently

75. Memory
What is flash memory?
Step 1.
Purchase and download MP3 music tracks
from a Web site. With one end of a special
cable connected to the system unit, connect
the other end into the MP3 player.
Step 2.
Instruct the computer to copy the MP3 music track
to the flash memory chip in the MP3 player.
Step 3.
Plug the headphones into the MP3
player, push a button on the MP3
player, and listen to the music through
the headphones.
MP3 Player
Flash memory chip
Flash memory card
From computer
To headphones
 Nonvolatile memory that can be erased electronically and
reprogrammed
 Used with PDAs, digital cameras, digital cellular phones, music players,
digital voice recorders, printers, Internet receivers, and pagers

76. Memory
What is CMOS?
Uses battery
power to retain
information when
other power is
turned off
Stores date,
time, and
computer’s
startup
information
Complementary
metal-oxide
semiconductor
memory
Used in some
RAM chips, flash
memory chips, and
other types of
memory chips

77. Memory
What is access time?
 Amount of time it takes processor
to read data from memory
 Measured in nanoseconds (ns),
one billionth of a second
 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
Term Speed
Millisecond One-thousandth of a second
Microsecond One-millionth of a second
Nanosecond One-billionth of a second
Picosecond One-trillionth of a second

78. Putting It All Together
What are recommended storage devices for home
users?
Home
 3.5-inch high-density floppy disk
drive
 250 MB Zip drive
 80 GB hard disk
 Internet hard drive
 CD or DVD drive
 Card reader/writer

79. Putting It All Together
What are recommended storage devices for small
office/home office (SOHO) users?
 3.5-inch high-density floppy disk
drive
 750 MB Zip drive
 100 GB hard disk
 Internet hard drive
 CD or DVD drive
 External hard drive for backupSmall Office/
Home Office (SOHO)

80. Putting It All Together
What are recommended storage devices for mobile
users?
 3.5-inch high-density floppy disk drive
 2 GB PC Card hard disk or USB Flash Drive
 40 GB hard disk
 Internet hard drive
 CD or DVD drive
 Card reader/writer
 External or removable hard disk for backupMobile

81. Putting It All Together
What are recommended storage devices for large
business users?
 3.5-inch high-density floppy disk
drive
 160 GB hard disk
 CD or DVD drive
 Smart card reader
 Tape drive
 Network storage server
 40 TB hard disk system
 CD-ROM or DVD-ROM server
 Microfilm or microfiche
Large Business

82. Putting It All Together
What are recommended storage devices for power
users?
 3.5-inch high-density floppy disk drive
 CD or DVD drive
 250 GB hard disk
 Internet hard drive
 External or removable hard disk for
backup
Power

83. Summary of Chapter 2
Floppy disksFloppy disks
Zip disksZip disks
Internal hard disksInternal hard disks
External hard disksExternal hard disks
Removable hard disksRemovable hard disks
CD-ROMsCD-ROMs
CD-RWsCD-RWs
DVD-ROMsDVD-ROMs
DVD+RWsDVD+RWs
TapeTape
PC CardsPC Cards
Flash memory cards and other
miniature mobile storage media
Flash memory cards and other
miniature mobile storage media
Microfilm and microficheMicrofilm and microfiche