Storage Devices. Storage Store information Storage involve two processes: Writing or recording the...
-
Upload
anissa-long -
Category
Documents
-
view
215 -
download
0
Transcript of Storage Devices. Storage Store information Storage involve two processes: Writing or recording the...
Storage Devices
Storage
• Store information• Storage involve two processes:• Writing or recording the data so it can be
found later for use,• Reading the store data, then transferring it
into the computers memory.
Storage
• The physical materials on which data is stored are called storage media. E.g., diskette.
• The hardware components that write data to, and read data from, storage media are called storage devices. e.g., diskette drive.
Store Information
• A storage device is a hardware device designed to store information. There are two types of storage devices used in computers; a 'primary storage' device and a 'secondary storage' device.
Primary storage Secondary storage
Storage Devices
p. 354 Fig. 7-1 Next
Storage devices are used to data and programs permanently These devices are used to store large volume of data and program Also called backing storage devices ,secondary storage devices,
or auxiliary devices
Storage Medium(floppy disks,
hard disks, CDs)
Storage• How does volatility compare?
p. 356 Next
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)
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
Types of Storage Media
Magnetic DiskOptical DiskSolid State Storage
Magnetic Disk It is most widely used storage media. A magnetic disk is a thin, circular metallic plate coated with
magnetic material. Information can be recorded on or read from the magnetic
surfaceFollowing are the types of Magnetic Disks:1. Floppy Disk2. Hard Disk
Magnetic 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
Magnetic Disks• What is a floppy disk drive?
Next
Floppy disk drive built intoa desktop computer
External floppy disk drive attaches toa computer with a cable
Also called secondary storage
One floppy drive, named drive A
Device that reads from andwrites to floppy disk
Magnetic Disks• What is a write-protect notch?
Next
Small opening with a cover that you slide Protects floppy disk from being erased accidentally
write-protected
not write-protected
notch closedmeans you
can write onthe disk
notch closedmeans you
can write onthe disk
notch openmeans you
cannot writeon the disk
notch openmeans you
cannot writeon the disk
Magnetic Disks• What is a hard disk?
Next
hard disk installedin system unit
High-capacity storage Consists of several
inflexible, circular plate that store items electronically
Components enclosed in airtight, sealed case for protection
Magnetic Disks
• Characteristics of Hard Disk:• Some important characteristics of Hard Disk are as follows: It provides large storage capacity The capacity of computer hard disk is from 2 to 80 GB and
more It is much faster than Floppy Disks It is used for storing data and programs It is more reliable than floppy disk Data stored on hard disk is safer than floppy disk
Push the same buttonto close the tray.
Optical Discs• What are optical discs?
Next
Most PCs include an optical disc drive
Flat, round, portable metal discs made of metal, plastic
Optical disk uses laser technology to read and write data
Can be read only or read/write
Optical disk storage
capacity is from 600 MB to over 1 GB with 14,500 tracks per inch (tpi).
It is much safer than magnetic media
Insert the disc,label side up.
Push the button toslide out the tray.
Optical Discs
• How should you care for an optical disc?
p. 368 Fig. 7-22 Next
Do store thedisc in a jewelbox whennot in use
Do hold a discby its edges
Do noteat, smoke, ordrink neara disc
Do not stack discs
Do not exposethe disc to excessiveheat or sunlight
Do not touchthe undersideof the disc
Optical Discs• Categories of Optical disks:1. CD2. DVD
• CD: Stands for Compact Disk It is most widely used media today A single CD can store from 650 MB to 1 GB The contents of CD can be read by CD driveDifferent types of CDs are as follows:1. CD-ROM2. CD-R3. CD-RW
Optical Discs• What is a CD-ROM?
Next
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
Optical Discs• What are CD-Rs and CD-RWs?
Next
Must haveCD recorder
or 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 Discs•Digital Video Disk (DVD)It is similar to CD-ROMIt uses laser beamsIts storage capacity is much greater than CD-ROMIt can store up to 17 GB of data
Next
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
Optical Discs
1. DVD-R– Stands for Digital Video Disk Recordable– It is similar to CD-R– The user write data on DVD-R only once but can read many
times– The data written on it cannot be erased
2.DVD-RW– it stands for Digital Video Disk rewritable– The user can write data on it many times by erasing the existing
contents