Transcript uploads/6/3/1/7/63175405/1storage_devices_powerpointx

Storage
devices
Chapter 5 Storing data of
norton book
Chapter 6 of capron and
johnson book
Three major types of storage
devices
magnetic page 174 of Norton book
 Optical. Page 183 norton
 Solid state page 189 norton
 Magnetic 2 types:
 1. floppy drive, defunct technology.
 Hard disk drive

Floppy drive
 How
data is stored on a disk
 Tracks
 Sector
 Clusters
 Capacity in a floppy diskette=
2 sides* 80 tracks* 18 sectors* ½ KB per
sector=1440 KB
https://www.youtube.com/watch?v=x2eJ6T
NrMew
Diskette cont.
 How
OS organizes data on a disk
 4 types of sector:
 Boot sector : BIOS, POST, files necessary to
boot(start) the OS.
 FAT(File Allocation Table): A log or table
that contains list of files and location and
status of the files
Diskette cont.
FAT example simplified
File name
Location
Zahid.doc
Side0, track 76,
sector 10-15
Status
Diskette cont.
Root folder: master folder that contains the
addresses and architecture of all folder and subfolders within
 Data area: where we save our files and programs.
Types of FAT:
1.FAT/FAT16: for MS-DOS
2.FAT 32: windows 9x,namely 95,98,and Me Windows
3.x namely 3.0,3.1and 3.11
3. NTFS: Windows NT
4.NTFS5: windows 2000 and XP
5. HPFS: IBM OS/2
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Performance metrics of drives
 1.Maximum
access time:
 Larger of the two following times
1. time for one revolution
 A diskette moves at 300 rpm(revolutions or
rotations per minute).
 Each rotation takes about 300/60=0.2 sec
2. Time to move from center to the edge
=0.17 sec
Metrics cont.
 2.
Seek time: time to move access arm to
a a particular track
 3. Head switching time: As read/write
head is fixed with access arm, only one
read/write head is functional at a time.
Time taken to activate a particular
read/write head.
 4. rotational delay: half the time it takes
for a rotation
Hard disk drives
 https://www.youtube.com/watch?v=kdm
Lvl1n82U
 https://i-technet.sec.smsft.com/dynimg/IC306536.jpg
Removable high capacity
magnetic storage
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1. Zip drive: although floppy disks became
obsolete due to low capacity and less
durability, another storage systems using the
same technology were introduced called Zip
drives which had much higher capacity,
made by companies Iomega and Imation.
External Hard disk: same as internal hard disk.
only difference external disks are hot
swappable meaning you can disconnect the
disks while the system is ON.
Removable media cont.
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RAID: Redundant Array of
Independent/Inexpensive Disks: an array of
parallel, hot-swappable disks utilizing different
backup techniques such as:
A. mirroring: same thing is copied to 2 disks
B. Striping: file is divided into two smaller sub-files
and fed into 2 disks so the writing takes half the
time.
C. striping with parity: the file is divided into two
sub-files and fed into two disks. At the same time
two copies these sub-files are copied onto 2 other
disks.
Tape drives
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Another kind of magnetic media is used to back up
files. It looks like the audio cassette of earlier days.
Only distinction is it uses digital data whereas
cassette uses analog data.
Tape drive is a type of sequential access device vs.
magnetic, optical and solid state devices are
random access devices.
Random access devices are also called DASD(Direct
Access Storage Devices) meaning devices which has
files which have distinct location and address any
two files can be accessed one after another but in
the case of sequential devices if you want to go from
one file to file you have to search through all the files
in between.
Optical storage
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CD-ROM players:
A CD-ROM is made from a finely polished
aluminum film sandwiched in between two
protective layers of plastic covers.
A read write mechanism of laser light source,
lens, mirror and prism directs the light.
Light is thrown onto the aluminum film where
land and pits are created as 1s and 0s.
Flat space=land=1 bit
Hollowed/ depressed space=pit=0 bit
Types of optical storage
 Audio
CD:650 MB or 70 minutes of audio
 CD-ROM:700 MB or 80 minutes of audio
 VCD: for video
 DVD-ROM:
 a. one sided 4.7 GB
 Two sided 7.4 GB
 Dual layer:17.4
 Blu-ray: 24 GB
DVD
 Format
war:
 1980s: betacam by Sony vs. VHS by
Panasonic
winner VHS due to low-cost
 2000s: HD DVD by Toshiba Vs. blu-ray by
Sony .
Winner blu-ray due to high-capacity.
Recordable optical
technologies
 1.CD-R(CD-Recordable):
recordable only
once. Used by music companies and
software providers
 2.CD-RW(CD-ReWritable): re-writable upto
100 times due to the limitation posed by
the writing mechanism which actually
makes holes onto the aluminum film. So
there is a limitation on the no of
read/write cycle
Recordable contd.
 PhotoCD:
 DVD-R
 DVD-RAM
by Kodak used in photo studios.
Solid state storage devices
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https://www.youtube.com/watch?v=viac3j6MeII
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Solid state devices store information in the form of
charge carriers such as electrons completely
confined in a solid state electronics such as
IC(integrated Circuits) as opposed to vacuum
tubes of earleir years.
Solid state devices have no moving parts as
opposed to electro-mechanical devices such as
hard disks and electro-optical devices such as CDROM players.
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Solid state
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Solid state devices use flash memory invented
by Dr Fujio Masuoka while working at Toshiba
in 1984.
Flash memory is a type of non-volatile
EEPROM(Electrically Erasable Programmable
Read Only Memory).
Flash memory is made of either NAND gate or
NOR gate memory.
NAND gate is faster and less expensive that’s
why more popular whereas NOR gate is
slower but more expensive. So no longer used
Flash memory
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NAND gate memory writes in blocks of 512, 2048 or 4096
bytes vs. NOR gate write in single byte size. That’s why
NAND memory is faster.
NAND cell is smaller hence less expensive
 Operating Principle:
An Intermediate voltage between two threshold voltage
(lowest and highest) is applied. E.g. if threshold voltages are
0 Volt and 1 Volt. An intermediate voltage of 0.5 volt is
applied.
If the transistor conducts electricity that means it not
already charged. So logical 1 is stored in the transistor.
If the channel does not conduct electricity that means it is
already charged. so a logical 0 is stored
Flash
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Major flash memory manufacturers:
Kingston technology
SanDisk
Intel
Micron Technology USA
Infineon technologies Germany formerly a
division of Siemens
Samsung
SK Hynix both from korea
Elpida memory of Japan.
Flash memory uses
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USB/flash/pen drive: first introduced by M-Systems
of Israel later acquired by SanDisk.
Memory Card: different types of memory card
standards were introduced such as
1. PC card or PCMCIA card used by modems,
routers,
2.Compact Flash used by professional camera.
3.Secure Digital or SD card used by consumer
camera. Which had many variants:
a. in size: SD, miniSD, microSD
b. in capacity: SD,SDHC(high
capacity),SDXC(extended capacity.
Flash memory
 4.Memory
stick, intelligent stick, magic
gate used by Sony
 MMC(MultiMediaCard)
 SD/MMC are winners