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Chapter 7
Storage
Storage• What is storage?
Holds data, instructions, and information for future use Storage medium is physical material used for storage
Also called secondary storage What is a storage device?
It is the computer hardware that records and/or retrieves items to and from storage media.
What is reading? It is the process of transferring information from a storage medium into
memory.
Magnetic Disks• Magnetic Disks: they use magnetic particles to store items
such as data, instructions and information on a disk’s surface.
• Formatting: it is the process of dividing the disk into tracks and sectors so the operating system can store and locate data and information on the disk.
• Track: it is a narrow recording band that forms a full circle on the surface of the disk.
• Sectors: the disk storage locations consist of pie-shaped sections which break the tracks into small arcs. A sector stores 512 bytes of data.
• Clusters: for reading and writing purposes, sectors are grouped into clusters. It is the smallest unit of disk space that stores data and information. Also called allocation unit.
Magnetic Disks•What are tracks and sectors?
Formatting prepares disk for use and marks bad sectors as unusable
Trackis narrow
recording bandthat forms fullcircle on disk
Sector stores up
to512
bytesof data
Magnetic Disks• What is a hard disk?
Also called the hard disk drive
It is a storage device that contains one or more inflexible circular platters that magnetically store data, instructions and information.
It is inside an airtight, sealed case inside the system unit.
hard disk installedin system unit
Magnetic 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
Online Storage
• What is online storage?
– It is a service on the web that provides hard disk storage to computer users for a 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
Floppy Disks Floppy disks are also called a
diskette. It is Portable, inexpensive
storage medium. Thin, circular, flexible film
enclosed in 3.5” wide plastic shell.
Floppy disk drive is a device that reads from and writes on a floppy disk. It is also called a secondary
storage. It is assigned to as DRIVE
A:/
shutter
shell
liner
magneticcoating
flexible thin film
metal hub
Push the same buttonto close the tray.
Optical DiscsWhat are optical discs?
It is a type of storage media that consists of a Flat, round, portable metal discs made of metal, plastic, and lacquer
Can be read only or read/write
Most PCs include an optical disc drive
Insert the disc,label side up.
Push the button toslide out the tray.
Optical Discs• How is data stored on an optical disc?
Typically stored in single track
Track divided into evenly sized sectors that store items
single trackspirals to edgeof disc
disc sectors
Types of Optical Discs
• CD-ROM• CD-R• CD-RW• DVD-ROM• DVD-R• DVD+R• DVD-RW• DVD+RW• DVD+RAM
Optical Discs
• What is a CD-ROM?
Compact disc read-only memory
It is a type of optical disc that users can read but not write or erase.
Typically holds 650 MB to 1 GB Commonly used to distribute
multimedia and complex software
Optical Discs• 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
Optical Discs• What are CD-Rs and CD-RWs? Must have
CD recorderor CD-R drive
Cannot erasedisc’s contents
CD-R (compact disc-recordable)—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
Optical DiscsWhat is a DVD-ROM (digital versatile disc-ROM or digital video disc-ROM)?
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 27 GB
HD-DVD discs have storage capacity of up to 45 GB
UMD can store up to 1.8 GB
PC Cards• What is a PC Card?
Adds capabilities to computer
Credit-card-sized device commonlyused in notebook computers
Miniature Mobile Storage Media
It allows mobile users easily to transport digital images, music, or documents to and from computers and other devices.
Storage for small mobile devices
Miniature Mobile Storage Media
• What is a USB Flash Drive? Also called as a pen device Plugs in a USB port on a computer or
mobile device It is convenient for mobile users
because they are small and lightweight enough to be transported on a key chain or in a pocket.
Storage capacities up to 4 GB May eventually make the floppy disk
obsolete
Miniature Mobile Storage Media
• What is a smart card?
It is similar in size to a credit card.
Stores data on microprocessor embedded in small card
It contains: Processor Input, Process, Output, and Storage capabilities