Storage - Shasha iSeminar
Objectives
Differentiate among CD-ROMs,
recordable CDs, rewritable CDs,
DVD-ROMs, BD-ROMs, HD DVDROMs, recordable DVDs, and
rewritable DVDs
Differentiate between storage devices
and storage media
Describe the characteristics of
magnetic disks
Storage
Identify the uses of flash memory and
tape
Describe the characteristics of
a hard disk
Discuss PC Cards, ExpressCard
modules, and the various types of
miniature storage media
Discuss various types of miniature,
external, and removable hard disks
Describe the characteristics
of optical discs
Describe cloud storage
From: Discovering Computers: Living in a Digital World”
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Storage
Storage
Storage
What is storage?
Holds data, instructions, and information for future use
Storage medium is physical material used for storage
Storage Device
Storage Media
Also called secondary storage
Primary Storage
(referred to as
Memory)
Secondary
Storage
Hard Disk drive
RAM
Optical Disks
CD/DVD drives
ROM
Magnetic Disks
Floppy Drive
CMOS, Cache,
registers
Mobile storage
USB port / card
slots
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4
Cloud Storage
Storage
Storage
What is capacity?
How does volatility compare?
Storage medium is nonvolatile—contents retained when
power is off
Memory is volatile—holds data and instructions temporarily
Nonvolatile
Volatile
Number of bytes (characters) a storage medium can hold
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ON
OFF
Screen Display
Display
appears
Display
disappears
Memory
(most RAM)
(chips on motherboard)
Data and
instructions
available to user
Data and
instructions erased
Storage Medium
(floppy disks, Zip disks,
hard disks, CDs)
Contents
available to user
Contents
retained
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1
Storage
Storage
Access time measures:
A storage device is the computer hardware that records
and/or retrieves items to and from storage media
The amount of time it
takes a storage device to
locate an item on a
storage medium
The time required to
deliver an item from
memory to the processor
Reading is the process
of transferring items
from a storage medium
into memory
Writing is the process
of transferring items
from memory to a
storage medium
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Magnetic Disks
Magnetic Disks
What are tracks and sectors?
What is a hard disk?
Track
is narrow
recording band
that forms full
circle on disk
hard disk mounted
in system unit
High-capacity storage
Consists of several
inflexible, circular
platters that store items
electronically
Components enclosed in
airtight, sealed case for
protection
Sector
stores up to
512 bytes
of data
Longitudinal recording
Perpendicular recording
Formatting prepares disk for use
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Hard Disks
Magnetic Disks
Formatting is the process of dividing the disk into tracks
and sectors so that the operating system can store and
locate data and information on the disk
What is a head crash?
Occurs when read/write head touches platter surface
Spinning creates cushion of air that floats read/write head above platter
11
Clearance between head and platter is approximately two-millionths of an inch
A smoke particle, dust particle, or human hair could render drive unusable
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2
Magnetic Disks
Magnetic Disks
What is a miniature hard disk?
What are external hard disks and removable hard disks?
Provide greater storage capacities than flash memory
Smaller than notebook computer hard disks
A pocket hard drive is a self-contained unit
Used to back up or transfer files
Removable hard disk—hard disk
that you insert and remove
from hard disk drive
External hard disk—freestanding
hard disk that connects to system unit
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Magnetic Disks
Optical Discs
What is a floppy disk?
What are optical discs?
Portable, inexpensive storage
medium (also called diskette)
Thin, circular, flexible film enclosed
in 3.5” wide plastic shell
Flat, round, portable
metal discs made of
metal, plastic, and
lacquer
Can be read only or
read/write
Push the button to
slide out the tray.
Insert the disc,
label side up.
Most PCs include an
optical disc drive
Push the same button
to close the tray.
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16
Optical Discs
Optical Discs
Optical discs
commonly store items
in a single track that
spirals from the
center of the disc to
the edge
Track is divided into
evenly sized sectors
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3
Optical Discs
Optical Discs
How should you care for an optical disc?
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
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20
Optical Discs
What are CD-Rs and CD-RWs?
Optical Discs
What is a DVD-ROM (digital versatile
disc-ROM or digital video disc-ROM)?
Must have
CD recorder
or CD-R drive
CD-R (compact disc-recordable)
— disc you can write on once
c
Cannot erase
disc’s contents
CD-RW (compact disc-rewritable)
— erasable disc you can write on
multiple times
ce
Must have
CD-RW software
and CD-RW drive
Must have DVD-ROM drive or
DVD player to read DVD-ROM
Stores databases, music,
complex software, and movies
Blu-ray discs have storage
capacity of up to 100 GB
HD-DVD discs have storage
capacity of up to 60 GB
UMD can store up to 1.8 GB
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Optical Discs
Flash Memory Storage
Flash memory chips are a type of solid state media
and contain no moving parts
Solid state drives (SSDs) have several advantages
over magnetic hard disks:
How does a DVD-ROM store data?
Two layers of pits are used, lower layer is
semitransparent so laser can read through
Some are double-sided
Many types of recordable and rewritable DVDs are
available
DVD-R and DVD+R
DVD-RW and DVD+RW
Faster access time
Faster transfer rates
Generate less heat and
consume less power
Last longer
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4
Flash Memory Storage
Flash Memory Storage
A memory card is a removable flash memory device that
you insert and remove from a slot in a computer, mobile
device, or card reader/writer
CompactFlash
(CF)
Secure Digital
(SD)
Secure Digital
High Capacity
(SDHC)
microSD
microSDHC
xD Picture
Card
Memory Stick
Memory Stick
Micro (M2)
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Flash Memory Storage
Flash Memory Storage
What is a USB Flash Drive?
Plugs in a USB port on a
computer or mobile device
Storage capacities up to 64 GB
May eventually make the
floppy disk obsolete
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Tape
PC Cards and ExpressCard Modules
What is tape?
What are PC Cards and ExpressCard Modules?
Magnetically coated plastic ribbon capable of storing large
amounts of data at low cost
Primarily used for backup
A tape drive reads and writes data and information on a
tape
29
Adds capabilities to computer
Credit-card-sized device commonly used in notebook
computers
An ExpressCard module is a removable device that fits in
an ExpressCard slot
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5
Other Types of Storage
Other Types of Storage
A magnetic stripe
card contains a
magnetic stripe that
stores information
A smart card stores
data on a thin
microprocessor
embedded in the card
Microfilm and microfiche store microscopic images of
documents on a roll or sheet film
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Other Types of Storage
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Other Types of Storage
Enterprise storage stores huge volumes of data and
information for large businesses
Uses special hardware for heavy use, maximum
availability, and maximum efficiency
33
Online Storage
Cloud Storage
Cloud storage is an Internet service that provides storage
to computer users
What is online storage?
34
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
Others can be authorized
to access your data
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Cloud Storage
Cloud Storage
Users subscribe to cloud storage for a variety of reasons:
Access files from any computer
Store large files instantaneously
Allow others to access their files
View time-critical data and images immediately
Store offsite backups
Provide data center functions
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