Copyright©2008 N.AlJaffan®KSU1 Storage Chapter 6.

Copyright©2008 N.AlJaffan®KSU 1

Storage

Chap

ter 6


Storage

Storage holds data, instructions and information for future use.

Storage medium, also called secondary storage,

Is the physical material on which a computer keeps data, instructions and information.

For Example: hard disks, floppy disks, Zip disks, CDs and DVDs, tape, Pc Cards, flash memory cards, USB flash devices and microfilm.

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Storage

Capacity is the number of bytes (characters) a storage medium can hold.

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Storage Term

Approximate number of bytes

Exact number of bytes

Kilobyte (KB)

1 thousand210 Or 1,024

megabyte (MB)

1 million220

Gigabyte (GB)

1 Billion230

Terabyte (TB)

1 trillion240

Petabyte (PB)

1 quadrillion250

Exabyte (EB)

1 quintillion260

Zettabyte (ZB)

1 sextillion270

Yottabyte (YB)

1 septillion280


Storage

Storage device is the computer hardware that records and/or retrieves items to and from storage media.

Writing is the process of transferring data, instructions, and information from memory to a storage medium.

Reading is the process of transferring these items from a storage medium into memory.

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Storage

The speed of storage devices is defined by The speed of storage devices is defined by access time.access time.

Access timeAccess time measures the amount of time measures the amount of time it takes a storage device to locate an item it takes a storage device to locate an item on a storage medium.on a storage medium.

The access time of storage device is slow The access time of storage device is slow ( millisecond ) , compared with the access ( millisecond ) , compared with the access time of memory ( nanosecond ). time of memory ( nanosecond ).

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Storage device

1-Magnetic Disks

Use magnetic particles to store items such as data, instructions and information on a disk’s surface.

Depending on how the magnetic particles are aligned, they represent either a 0 bit or a 1 bit.

Store data and instructions in tracks and sectors.

Track is an narrow recording band that forms a full circle on the surface of the disk.

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Track

Sector


Storage

Magnetic Disks

The disk’s storage locations consist of pie- shaped sections, which break the tracks into small arcs called sectors.

A sector typically stores up to 512 bytes of data.

Three type of magnetic disks are Hard disks ,Floppy disks and Zip disks.

Some of these disks are portable which means you can remove the medium from one computer and carry it to another computer; others are not.

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Storage

A- Hard Disks

Is a storage device that contains one or more inflexible, circular platter that store data, instructions and information.

The System unit on most desktop and notebook computers contains at least one hard disk.

The entire device is enclosed in an airtight, sealed case to protect it from contamination.

A hard disk that is mounted inside the system unit sometimes is called a fixed disk because it is not portable.

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Storage

Hard Disks

Current personal computer hard disks have storage capacities from 80 to 500 GB and more.

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Storage

Characteristics of a Hard Disks

The capacity of a hard disk is The capacity of a hard disk is determined from the number of determined from the number of platters it contains.platters it contains.

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Copyright©2008 N.AlJaffan®KSU`

11

Storage


PlatterPlatter is made of aluminum, glass, or is made of aluminum, glass, or ceramic and is coated with an alloy ceramic and is coated with an alloy material that allows items to be recorded material that allows items to be recorded magnetically on its surface.magnetically on its surface.

On desktop computer, platters most often On desktop computer, platters most often have size of approximately 3.5 inches in have size of approximately 3.5 inches in diameter.diameter.

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Storage


While the computer is running, the platters rotate at a high rate of speed.

The platters typically continue to spin until power is removed from the computer.

On many computers, the hard disk stops spinning after a specified time to save power.

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Storage


Backup is a duplicate of a file, program, or disk that you can use in case the original is lost, damaged, or destroyed.

Access time for today’s hard disks ranges from approximately 3 to 12 ms (milliseconds).

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Storage

Miniature Hard Disks

Many mobile device and consumer electronics include miniature hard disks.

These tiny hard disks are found in devices such as audio players, digital cameras, smart phones, and PDAs.

It has a greater storage capacities than flash memory.

Miniature hard disk have storage capacities that range from 2 GB to 120 GB.

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Storage

Portable Hard Disks

Its either are external or removable and have storage capacities up to 500 GB or higher.

The entire hard disk is enclosed in an airtight, sealed case.

External hard diskExternal hard disk is a separate freestanding hard disk that connects with a cable to a USB port or FireWire port on the system unit.

Removable hard diskRemovable hard disk is a hard disk that you insert and removed from a drive.

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Storage

Portable Hard Disks

Portable hard disk offer the following advantages over internal hard disks( fixed disk):

Transport a large number of files. Back up important files or an entire internal hard

disk (Several external hard disk models allow you Several external hard disk models allow you to back up simply by pushing a button on the to back up simply by pushing a button on the diskdisk ))..

Easily store large audio and video files.Easily store large audio and video files. Secure your data.Secure your data. Add storage space to computer without having to Add storage space to computer without having to

open the system unit.open the system unit. Share a drive with multiple computer.Share a drive with multiple computer.

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Storage

Online Storage

Is a service on the web that provides hard disk storage to computer users usually for a minimal monthly fee.

User subscribe to an online storage service for a variety reasons:

To access files on the Internet hard disk from any computer or device that has Internet access.

To share these file with other people instead of e-mailing the files to them.

To store backups of data.

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Storage

B- Floppy Disks, also called Diskette

Is a portable, inexpensive storage medium that consists of a thin, circular, flexible plastic film with a magnetic coating enclosed in square shape plastic shell

A typical floppy disk is 3.5 inches wide and can store up to 1.44 MB.

You can read from/ write on a floppy disk any number of times.

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Storage

Floppy disk drive Is device that read from/write on floppy disk.

User inserts diskette in and removes it from floppy device

In past PCs and notebook computers had a floppy drive installed inside the system unit.

Most computer today do not include a floppy disk driver as standard equipment. On these computer you can use external floppy disk drive.

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Storage

C- Zip Disks

Is a type of portable magnetic media that can store from 100 MB to 750 MB of data.

Zip Drive

Is a high capacity disk drive developed by Iomega Corporation that reads from and writes on a Zip disk.

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Storage

2-Optical Discs

Is a type of optical storage media that consists of a flat, round, portable, disc made of metal, plastic.

The Disc Size usually are 4.75 inches in diameter.

Some Optical disc formats read only, others are read/write.

Every PC today includes some type of optical disc drive installed in a drive bay.

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Storage

Optical Discs

With some discs, you can read and / or write on one side only. Other discs are double-sided.

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Storage

Optical Discs

Optical discs store items by using microscopic pits ( indentations) and lands (flat areas) that are in the middle layer of the disc.

A high-powered laser light create the pits.A low-powered laser reads items from the disc by

reflecting light through the bottom of the disc, which usually is either solid gold or silver in color.

The reflected light is converted into a series of bits the computer can process

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StorageOptical DiscsMany different formats of optical discs exist

today. DVDs having a much greater storage capacity than CDs.

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Optical DiscReadWriteErase

CD-RomYNN

CD-RYYN

CD-RWYYY

DVD-ROMYNN

DVD-R /DVD+RYYN

DVD-RW / DVD+RW/ DVD+RAM

YYY


Storage

CD-ROMS

Compact disc read-only memory, is a type of optical disc that users can read but not write ( record) or erase.

Manufacture write the contents of standard CD-ROM.

A standard CD-ROM is called a single-session disc because manufacturers write all items on the disc at one time.

SW manufactures often distribute programs using CD-Rom.

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Storage

CD-ROMS

CD-ROM hold from 650 MB to 1 GB of data.

To read a CD-ROM, insert the disc in a CD-ROM driver or CD-ROM player.

Because audio CDs and CD-ROMs use the same laser technology, you may be able to use a CD-Rom driver to listen to an audio CD while working on the computer.

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Storage

CD-Rs and CD-RWs

Many Personal computers today include either a CD-R or CD-RW driver as a standard feature.

Un like CD-ROM drivers, users record or write their own data on a disc with a CD-R or CD-RW driver.

The process of writing on an optical disc is called burning.

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Storage

CD-Rs and CD-RWs

CD-R ( compact disc-recordable) is a multisession optical disc on which users can write but not erase, their own items or data.

Multisession means you can write on part of the disc at one time and another part at a later time.

Each part of a CD-R can be written on only one time, and the content cannot be erased.

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Storage

CD-Rs and CS-RWs

CD-RW ( compact disc-rewriteable) is an erasable multisession optical disc on which users can write on multiple times.

To write on a CD-RW disc, you must have CD-RW software and CD-RW drive.

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Storage

CD-Rs and CS-RWs

Using a CD-RW disc to back up large files from a hard disk or to create audio CDs.

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Storage

DVD-ROMs

Digital versatile disc-read-only memory or digital video disc-read-only memory

Is an extremely high-capacity optical disc on which users can read but not write or erase.

DVD-ROMs store movies, music, huge databases and complex software.

To read a DVD-ROM, you must have a DVD-ROM drive or DVD player.

Most DVD-ROM drives also can read audio CDs, CD-ROMs, CD-Rs and CD-RWs.

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Storage

DVD-ROMs

DVD-ROM Storage Capacity

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SidesLayersStorage Capacity

114.7 GB

128.5 GB

219.4 GB

2217 GB


Storage

Recordable and Rewritable DVDs

DVD-R and DVD+R allow users to write on the disc once and read it many times.

DVD-RW an DVD+RW , a user can erase and record more than 1,000 times.

DVD+RAM allows users to erase and record more than 100,000 times.

Many industry professionals expect that DVD eventually will replace all CD media.

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Storage

TAPE

One of the first storage media used with mainframe computer was tape.

Tape is a magnetically coated ribbon of plastic capable of storing large amounts of data and information at a low cost.

Tape no longer is used as a primary storage.

A tape drive reads and write data and information on a tape.

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Storage

TAPE

Tape storage requires sequential access, which refers to reading or writing data one after the other.

You must forward or rewind the tape to a specific point to access a specific piece of data.

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Storage

TAPE

Hard disks , CDs and DVDs all use direct access.

Direct access mean that the device can locate a particular data item or file immediately.

When writing or reading specific data, direct access is much faster than sequential access.

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Storage

Miniature Mobile Storage Media

Three types of Miniature mobile storage media:Flash memory cards, USB flash drives , and smart cards.

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Storage

Flash memory Cards

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Media Name

Storage Capacity

Use

CompactFlash64 MB to

8 GB

Digital Cameras, PDAS, Smart phone, photo printers, audio

players, notebook computers, Desktop

computer

Smart Media32MB to

128 MB

Digital Cameras, photo printers, audio

players.


Storage

Flash memory Cards

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Media Name

Storage Capacity

Use

Secure Digital64 MB to 1

GB

Digital Cameras, PDAS, Smart phone, photo

printers, music players, Digital video camera

xD Picture Card

64 MB to 1 GB

Digital Cameras, photo printers.


Storage

Flash memory Cards

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Media Name

Storage Capacity

Use

Memory Stick256 MB to

4 GB

Digital Cameras, PDAS, Smart phone, photo printers, handheld

game consoles, notebook computer


Storage

USB Flash Drives

Sometimes called a pen drive, is a flash memory storage device that plugs in a USB port on a computer or mobile device.

Become the mobile user’s primary storage device.

Current USB flash drive have storage capacities up to 4 GB.

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Storage

Smart Cards

Which is similar in size to a credit card or ATM card, stores data on a thin microprocessor embedded in the card.

Smart cards contain a processor and have input , process, output , and storage capabilities.

Uses of smart cards include storing medical records, and other health-care or identification information; tracking information such as customer purchases or employee attendance

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Storage

Microfilm and Microfiche

Microfilm and microfiche store microscopic images of documents on roll or sheet film.

Microfilm is a 100-to 215- foot roll of film.

Microfiche is a small sheet of film , usually about 4X6 inches.

A computer output microfilm recorder is the device that records the images on the film. You can read them only with microfilm or microfiche reader

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Storage

Microfilm and Microfiche

Libraries use these media to store back issues of newspapers, magazines and genealogy record.

Some large organization use microfilm and microfiche to archive inactive files.

Some banks use them to store transactions and canceled checks.

The advantages of using it :1. They greatly reduce the amount of paper that must handle.2. They are inexpensive and have the longest life of any

storage media.

Chap

ter 6

Copyright©2008 N.AlJaffan®KSU1 Storage Chapter 6.

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