ITBIS105 5

Chapter 3Storage

Storage

What is storage? Holds data, instructions, and information for future use Storage medium is physical material used for storage

Also called secondary storage such as : floppy disks, CDs, Zip disks

Storage Medium(floppy disks, Zip disks,

hard disks, CDs)

Storage

How does volatility compare?

No

nvo

lati

le

Storage medium is nonvolatile—contents retained when power is off

Contents Contents retainedretained

Contents Contents available to useravailable to user

Memory(most RAM)

(chips on motherboard)

Screen Display

ON OFF

Vo

lati

le Display Display disappearsdisappears

Data andData andinstructions instructions

available to useravailable to user

Display Display appearsappears

Data and Data and instructions erasedinstructions erased

Memory is volatile—holds data and instructions temporarily

The on/off state of a switch represents one bit of data.

Bit (binary digit) On = 1 Off = 0

OFF

0

Switches Representing Data

ON

1

01

OR = 1 bit

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Bits and Bytes: The Language of Computers

Bit Binary digit 0 or 1

Byte 8 bits

Each letter, number, and character = a string of eight 0s and 1s

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Representing Letters and Symbols

American Standard Code for Information Interchange (ASCII) 8 bits = 1 byte = alphanumeric character or

symbol 256 different combinations

Unicode 16 bits equal 1 byte 96,000 different combinations; used for all

languages

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How Much Is a Byte?

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WritingWritingProcess of transferring Process of transferring

items from memory items from memory to storage mediato storage media

WritingWritingProcess of transferring Process of transferring

items from memory items from memory to storage mediato storage media

Storage

What is a storage device?

ReadingReadingProcess of transferring Process of transferring

items from storage items from storage media to memorymedia to memory

ReadingReadingProcess of transferring Process of transferring

items from storage items from storage media to memorymedia to memory

Hardware that Hardware that records and records and

retrieves items retrieves items to and from to and from

storage mediastorage media

Functions as source of input

Creates output

 Hardware that records and retrieves items to and from a storage medium. Examples are Floppy drive, Hard disk drive etc.

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

Floppy Disks

What is a floppy disk? Portable, inexpensive storage

medium (also called diskette)

Thin, circular, flexible film enclosedin 3.5” wide plastic shell

shutter

shell

liner

magneticcoating

flexible thin film

metal hub

Floppy Disks

What is a floppy disk drive?

Floppy disk drive built intoa desktop computer

External floppy disk drive attaches toa computer with a cable

One floppy drive, named drive A If two floppy drives, second

designated as drive B

Device that reads from andwrites to floppy disk

Floppy Disks

What are tracks and sectors?

Trackis narrow

recording bandthat forms fullcircle on disk

Sector stores up to512 bytes

of data

Formatting prepares disk for use and marks bad sectors as unusable

Floppy Disks

     Tracks are configured in concentric circles in which data are stored. PC disks use sector organization to store and retrieve data. The recording surface is divided into sectors (a disk-storage concept of a pie-shaped portion of a disk or diskette in which records are stored and subsequently retrieved).

What are tracks and sectors?

Floppy Disks

Never open theshutter and

touch the disk’ssurface

Never open theshutter and

touch the disk’ssurface

How do you care for a floppy?

Avoid exposureto heat and

cold

Avoid exposureto heat and

coldAvoid exposure

to magneticfields

Avoid exposureto magnetic

fields Avoid exposureto contaminants

such as dust,smoke, or

salt air

Avoid exposureto contaminants

such as dust,smoke, or

salt airKeep disks ina storage tray

when notusing them

Keep disks ina storage tray

when notusing them

Proper care helps maximize disk’s life Floppy disk can last at least seven years

ExternalZip drive

Zip Disks

What is a Zip disk? Magnetic medium that stores 100 MB

or 250 MB of data

Zip disks require a Zip drive—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 lostc

Zip disk

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

Hard Disks

What are external hard disks and removable hard disks?

External hard disk—freestandinghard disk that connects to system unit

Removable hard disk—hard diskthat you insert and removefrom hard disk drive

Used to back up or transfer files

Push the same buttonto 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 with protective plastic coating

Can be read only or read/write

Insert the disc,label side up.

Push the button toslide out the tray.

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 distributemultimedia and complexsoftware

CDs and DVDs

What are CDs and DVDs?

 CD-ROM stands for compact disc-read-only memory.

 Once inserted in the CD-ROM drive, the text, video images, and so on can be read into RAM for processing or display.

 The data on the disk are fixed-they cannot be altered. This is in contrast to the read/write capabilities of magnetic disks.

What makes CD-ROM so inviting is its vast capacity to store data and programs. The capacity of a single CD-ROM is up to 680 MB-about that of 477 diskettes.

CDs and DVDs

What are CD-Rs and CD-RWs? Must haveCD recorder

or CD-R drive

Cannot erasedisc’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 haveCD-RW softwareand CD-RW drive

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

CDs and DVDs

What are CDs and DVDs?

 DVDs are poised to replace CD-ROMs. The DVD (digital videodisk) looks like the CD and the CD-ROM, but it can store from 7 to 14 times as mush information (up to about 10 GB). A DVD can store the video for a full-length movie.

 DVD drives are back-wards compatible; that is, they can play all of your CD-ROM and CDs. DVDs probably will replace videotapes and CDs in a few years  

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 trackspirals to edgeof disc

disc sectors

Tape

What is tape? Magnetically coated plastic ribbon

capable of storing large amountsof data at low cost

Primarily used for backup

Tape

How is data stored on a tape? Sequential access

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

Miniature Mobile Storage Media

What is miniature mobile storage media?

Storage for small mobile devices

Miniaturemobile storage

media

Miniature Mobile Storage Media

What are common types of miniature mobile storage media?

Smart Media Secure Digital

Microdrive ™ USBDrive™Memory Stick ®

CompactFlash

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Setting It All Up: Ergonomics

Ergonomics: minimizing injury or discomfort while using the computer

Steps to follow: Position monitor correctly. Use adjustable chair. Assume proper position while typing. Take breaks. Ensure adequate lighting.

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Ergonomics and Mobile Devices

Mobile devices present ergonomic challenges

Ergonomic “Disease” Cause

Blackberry thumb Thumb typing without breaks or stretching can cause DeQuervains’ tendinitis in the thumbs.

iPod deafness Listening through ear buds for prolonged periods at a volume of 80 decibels or more can cause deafness.

Cellular blindness Extended viewing on tiny screens can cause eye strain and/or dry eyes.

Laptop thighs Resting a laptop directly on your lap for extended periods of time can result in 1st and 2nd degree burns.

Laptop shoulder Large, heavy, one-strap laptop bags can result in neck, shoulder, and back pain and/or strain.

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