1. Magnetic storage devices
2. Optical storage devices
3. Solid state devices
4. Methods to prevent storage failures & data loss
5. Impact of virus attack on computer system
EC5103PA_Apr2008 ITECC/TP/ECE/SimBN 1

• The media (the disk) is coated with magnetic particles, the drive divides into microscopic areas called domains.
• Each domain acts like a tiny magnet, with north and south poles, represents either ‘0’ or ‘1’ depending on which way it is pointing.
• Information is read from, or written to, the media using a "head" .
• On a hard drive this head actually floats on a cushion of air created by the spinning of the disk.
• Hard and floppy disk drives are " random access " devices because the information is organised into concentric circles on the surface of the disks.
• This allows the head to go to any part of the disk and retrieve or store information quickly.
• http://computer.howstuffworks.com/hard-disk.htm/printable
• http://en.wikipedia.org/wiki/File:Hard_drive-en.svg
2

• Most hard disks have two to eight inflexible platters coated with material that allows the magnetic recording of
computer data.
• A typical hard disk rotates at 7200
RPM and the read/write heads ride over the surface of the disk.
• It is sealed to prevent contaminants.
• 5400/10000/15000rpm
• 20/40/80/120/160/300GB
• PC's hard disk serves as a non-volatile , bulk storage medium and as the repository for a user's documents, files and applications.
Fig 1
• 1997, IBM introduced the first hard drive with giant magnetoresistive (GMR) heads, the most advanced recording head enable data storage products with the industry's highest areal densities.
3

A hard disk drive with the metal cover removed.
4

A hard disk drive with the metal cover removed.
Date invented September 13, 1956
Invented by An IBM team led by Rey Johnson
Connects to
Host adapter (on PCs often integrated into motherboard ) via one of:
•
PATA (IDE) interface
• SATA interface
•
SAS interface
• SCSI interface (popular on servers)
•
FC interface (almost exclusively found on servers)
•
EIDE interface
• USB interface (for external/portable hard drives)
•
IEEE 1394 interface (for external/portable hard drives)
5

 two ways to measure performance of a hard disk:
– Data rate - number of bytes per second that the drive can deliver to the CPU.
– Seek time - amount of time between when the
CPU requests a file and when the first byte of the file is sent to the CPU.
 capacity of the drive is the number of bytes it can hold.
6

•
As of April 2009, the highest capacity HDDs are 2 TB .
•
A typical " desktop HDD" might store between 120 GB and 2 TB although rarely above 500 GB of data (based on US market data) rotate at 5,400 to
10,000 rpm and have a media transfer rate of 1 Gbit/s or higher. Some newer have 3Gbit/s.
• The fastest “enterprise” HDDs spin at 10,000 or 15,000 rpm, and can achieve sequential media transfer speeds above 1.6 Gbit/s. and a sustained transfer rate up to 125 MBytes/second. Drives running at 10,000 or 15,000 rpm use smaller platters to mitigate increased power requirements (due to air drag ) and therefore generally have lower capacity than the highest capacity desktop drives.
•
"Mobile HDDs" , i.e., laptop HDDs, which are physically smaller than their desktop and enterprise counterparts, tend to be slower and have lower capacity. A typical mobile HDD spins at 5,400 rpm, with 7,200 rpm models available for a slight price premium. Because of the
TB(Terabytes)=10 12 (1,000,000,000,000bytes) or 1000 gigabytes .
GB= 10 9 (1,000,000,000bytes)
7

Form factor Width Largest capacity
Platters
(Max)
5.25″ FH
5.25″ HH
3.5″
2.5″
146 mm
146 mm
102 mm
47
2
GB
TB
(1998)
19.3 GB(1998)
(2009)
69.9 mm 500 GB (2008)
14
4
4
3
1.8″ ( CE-ATA / ZIF )
1.3″
54 mm
43 mm
250 GB (2008)
40 GB (2007)
1″ (CFII/ZIF/IDE-Flex) 42 mm 20 GB (2006)
0.85″ 24 mm 8 GB (2004)
3
1
1
1
Full-height bays were found in old PCs in the early to mid-1980s, approximately 3.5" high by 5.75" wide, and used mainly for hard disks and floppy disk drives.
8

Disk interface families used in personal computers cronym or abbreviation
SASI
SCSI
SAS
ST-506
ST-412
ESDI
ATA
SATA
Meaning Description
Shugart Associates
System Interface
Small Computer
System Interface
Serial Attached SCSI
Historical predecessor to SCSI.
Bus oriented that handles concurrent operations.
Improvement of SCSI, uses serial communication instead of parallel.
Seagate Technology Historical Seagate interface.
Seagate Technology
Historical Seagate interface (minor improvement over ST-506).
Enhanced Small Disk
Interface
Historical; backwards compatible with ST-
412/506, but faster and more integrated.
Advanced
Technology
Attachment
Serial ATA
Successor to ST-412/506/ESDI by integrating the disk controller completely onto the device. Incapable of concurrent operations.
Modification of ATA, uses serial communication instead of parallel.
9

10

Close-up of a hard disk head resting on a disk platter, and its suspension. A reflection of the head and suspension are visible beneath on the mirrorlike disk.
An IBM HDD head resting on a disk platter. Since the drive is not in operation, the head is simply pressed against the disk by the suspension.
11

• Provides removable storage ranging from 340
MB, 500MB, 1 GB, 2GB, 4GB in a one-inch hard disk drive.
• Integrates with a variety of handheld devices through use of the industry- standard CF+** Type
II format and compatibility with PCMCIA Type II
(with an adapter).
• Provides reliable storage for digital cameras, handheld PCs, digital audio players, laptops, video camcorders, personal digital assistants
(PDA) and other portable handheld devices.
• Incorporates giant magnetoresistive (GMR) head technology, load/unload features for maximum capacity, performance, and reliability.
• By 2009 all manufacturers had discontinued the development of new products for the 1.3-inch, 1-inch and 0.85inch form factors due to falling prices of flash memory ,
12

• Optical storage refers to any storage device that uses laser light technology to retrieve and store data.
• It stores information in deformities on the surface of a circular disc and reads this information by illuminating the surface with a laser diode and observing the reflection.
• Optical disc storage is non-volatile .
• The deformities may be permanent ( read only media), formed once ( write once media) or reversible ( recordable or read/write media).
13

• Compact Disc (1982) : CD-R (1988)
·
CD-RW (1997)
• DVD (1995) : DVD-RAM (1996)
·
DVD-R (1997)
·
DVD-RW
(1999)
·
DVD+RW (2001)
·
DVD+R (2002)
·
DVD+R DL
(2004)
·
DVD-R DL (2005)
• Other : Microform (1870)
·
Optical tape
(1995) · Laserdisc (1958) · UDO (2003) · ProData
(2003) · UMD (2004) · Blu-ray Disc (2006) · HD DVD
(2006)
• Magneto-optic Kerr effect (1877): MO disc
(1988)
·
MiniDisc (1991)
• Optical Assist : Laser turntable (1986)
·
Floptical
(1991)
·
Super DLT (1998)
14

15

• CDs and DVDs are used to hold music, data or computer software.
• standard medium for distributing large quantities of information in a reliable package.
Compact Disk (CD)
• 1.2 mm thickness
• 120mm diameter
• store up to 640 (650) Mbytes of data or
• 74 minutes of music (CD-A)
• Replicated compact disk
• Some CD-R blanks can hold 80 minutes of audio, or about 700MB of data.
16

http://en.wikipedia.org/wiki/CD-ROM
17

Pit
Land ‘1’
•
•
•
•
Bump ‘0’ Fig 2
It consists of an injection-molded piece of clear polycarbonate plastic. Bumps are impressed. These microscopic bumps are arranged as a single, continuous, long spiral track of data.
A thin, reflective aluminum layer is sputtered onto the disk, covering the bumps.
A thin acrylic layer is sprayed over the aluminum to protect it.
The label is then printed onto the acrylic
18

Fig 3 Side-view of a CD
120 mm diameter
Fig 4 CD-data in spiral form
Fig 5 pits and bumps
Pits on aluminium side and bumps on the side where the laser read from
19

Consists of 3 components:
A drive motor spins the disc.
A laser and a lens system focus in on and read the bumps.
A tracking mechanism moves the laser assembly so that the laser's beam can follow the spiral track.
Fig 6 Inside a CDROM drive
20

21

• The fundamental job of the CD player is to focus the laser on the track of bumps. The bumps reflect light differently than the "lands" (the rest of the aluminum layer),
• Opto-electronic sensor detects that change in reflectivity.
• The electronics in the drive interpret the changes in reflectivity in order to read the bits that make up the bytes.
http://electronics.howstuffworks.com/cd5.htm
Fig 7 Block diagram of a CDROM player
22

LABEL COATING
LACQUER
REFLECTIVE
DYE SURFACE
POLYCARBONATE
Fig 8 CDR layer
Fig 9 Side-view of a CDR
23

24

•
The error correction of most modern optical drives/players can usually read effectively through fingerprints as well as a highly scratched information surface.
•
Dust can be removed from a CD's surface using compressed air or by very lightly wiping the information side with a very soft cloth (such as an eyeglass cleaning cloth) from the center of the disc in an outward direction.
• Wiping the information surface of any type of CD in a circular motion around the center, however, has been known to create scratches in the same direction as the information and potentially cause data loss.
• Fingerprints or stubborn dust can be removed from the information surface by wiping it with a cloth dampened with diluted dish detergent (then rinsing) or alcohol ( methylated spirits or isopropyl alcohol ) and again wiping from the center outwards, with a very soft, cloth (non-linting : polyester, nylon, etc.).
•
It is harmful, however, to use acetone , nail polish remover, kerosene , petrol/gasoline , or any other type of petroleum-based solvent to clean a CD-R; the use of petroleum based solvents will damage the polycarbonate surface and the CD-R will become unreadable.
25

•
(December 2007) There was some incompatibility with CD-Rs and older CD-ROM drives. This was primarily due to the lower reflectivity of the CD-R disc . In general, CD-ROM drives marked as 8x or greater will read CD-R discs. Some DVD players will not read CD-Rs because of this change in reflectivity as well.
• Burn speed can also affect the compatibility due to worse jitter on disks recorded at higher speeds; selecting a slower speed can improve compatibility, especially for CD-DA.
• However, for writing some burners may not perform best at their lowest speed, and may not perform best on all discs at the same speed; each burner/media combination has an optimal speed which is most likely a lower rather than higher speed but can only be certainly known by testing that combination at different speeds (using disc checking software such as that which reports C1/C2 errors to compare the quality of readable discs.).
26

Bump ‘0’
Write Laser
Fig 10 Comparison of CD and CDR
Blank CD-R logic 1(translucent)
27

Fig 11
Fig 12
28

• To record data, the burner turns the laser writer on and off in synch with the pattern of 1s and 0s.
• The laser darkens the material to encode a 0 and leaves it translucent to encode a 1 .
• Most CD burners can create CDs at multiple speeds.
• At 1x speed, the CD spins at about the same rate as it does when the player is reading it. It takes 60 minutes to record 60 minutes of music.
• At 2x speed, it would take about half an hour to record 60 minutes.
• 1010000 = off on off on on on on write laser
29

Advantages
• The main advantage of CD-R discs is that they work in almost all CD players and CD-ROMS.
• CD-Rs are relatively inexpensive.
Disadvantages
• can't reuse the discs.
• Once you've burned in the digital pattern, it can't be erased and re-written.
30

Write Laser
Fig 13 CDRW disk
31

• CD-RW based on phase-change technology.
• Two phases:
1. Amorphous phase (fluid) ‘0’ translucent
When the phase change compound is heated above its melting temperature (around
600 o C), it becomes a liquid.
2. Crystalline phase (solid) ‘1’ opaque, blank CD o
At crystallization temperature (200
C), it turns into a solid.
32

• CD RW drive has three laser powers :
– Read
• the lowest power which does not alter the state of the recording layer, so it can be used for reading the data.
– Erase
• the middle power which melts the recording layer and converts it to a reflective crystalline state
– Write
• the highest laser power which creates a non-crystalline
(absorptive) state on the recording layer
33

• for playback of large amounts of data.
• Originally known as digital versatile disk or digital video disk .
• Looks like CD-ROM. Same size as CD-ROM.
• hold 4.7Gbytes of data
• Up to 133 minutes of high-resolution video, with 720 dots of horizontal resolution (The video compression ratio is typically
40:1 using MPEG-2 compression.)
• equivalent of 25 CD-ROMs
• 8 hrs of CD-quality music/side.
• Reasons for DVDs can store more data than CDs :
– Higher-density data storage
– Less overhead, more area
– Multi-layer storage
– http://en.wikipedia.org/wiki/DVD
34

•
MPEG-2 is an extension of the MPEG-1 international standard for digital compression of audio and video signals.
• While MPEG-2 is the core of most digital television and DVD formats
• MPEG-1 was designed to code progressively scanned video at bit rates up to about 1.5 Mbit/s for applications such as CD-i (compact disc interactive).
•
MPEG-2 is directed at broadcast formats at higher data rates; it provides extra algorithmic 'tools' for efficiently coding interlaced video, supports a wide range of bit rates and provides for multichannel surround sound coding.
35

• http://en.wikipedia.org/wiki/DVD_region_codes
• DVD region codes are a DRM scheme. DVD video discs may be encoded with a region code restricting the area of the world in which they can be played.
• Discs without region coding are called all region or region 0 discs.
• The commercial DVD player specification requires that a player to be sold in a given place not play discs encoded for a different region
(region 0 discs are not restricted).
• The purpose of this is to allow motion picture studios to control aspects of a release, including content, release date, and, especially, price, according to the region.
• Many DVD players are or can be modified to be region-free , allowing playback of all discs.
36

0
1
2
3
4
Informal term meaning "worldwide". Region 0 is not an official setting; discs that bear the region 0 symbol either have no flag set or have region 1–6 flags set.
Canada, United States; U.S. territories; Bermuda
Western and Central Europe; Western Asia; Israel, Iran, Egypt,
Japan, South Africa, Swaziland, Lesotho; United Kingdom,
Turkey, French overseas territories
Southeast Asia; South Korea; Taiwan; Hong Kong; Macau
Mexico, Central and South America; Caribbean; Australia; New
Zealand; Oceania;
5 Ukraine, Belarus, Russia, Continent of Africa, Central and South
Asia, Mongolia, North Korea.
People's Republic of China 6
7 Reserved for future use (found in use on protected screener copies of MPAA-related DVDs and "media copies" of prereleases in Asia)
8 International venues such as aircraft, cruise ships, etc.
ALL Region ALL discs have all 8 flags set, allowing the disc to be played in any locale on any player.
37

Fig 14 DVD layer format
Fig 15 DVD pit layout Fig 16 Spiral track of data
38

• A DVD player is very similar to a CD player.
• It has a laser assembly that shines the laser beam onto the surface of the disc to read the pattern of bumps.
• It consists of 3 components:
– A drive motor spins the disc
– A laser and a lens system focus in on and read the bumps.
– A tracking mechanism moves the laser assembly so that the laser's beam can follow the spiral track.
• The fundamental job of DVD player is to focus laser on the track of bumps .
• The hardest part of reading a DVD is keeping the laser beam centered on the data track . This centering is the job of the tracking system .
39

Fig 17
40

• As the DVD is played, the tracking system has to move the laser continually outward.
• As the laser moves outward, spindle motor must slow down the spinning of the DVD so that the bumps travel past laser at a constant speed, and the data comes off the disc at a constant rate.
• If a DVD has a second layer, the start of that layer's data track can be at the outside of the disc instead of the inside. http://electronics.howstuffworks.com/dvd6.htm
Fig 18 Reading the disc
Near centre: Shorter radius x higher speed
Away from centre:Longer radius x lower speed
41

Here are the typical contents of a DVD movie :
– Up to 133 minutes of high-resolution video, in letterbox or pan-and-scan format, with 720 dots of horizontal resolution (The video compression ratio is typically 40:1 using MPEG-2 compression )
– Soundtrack presented in up to eight languages using
5.1 channel Dolby digital surround sound
– Subtitles in up to 32 languages
DVD can also be used to store almost eight hours of CD-quality music per side.
42

– Watch high-quality movies with good sound.
– DVD movies quality is better, and many of them have Dolby
Digital or DTS sound, which is much closer to the sound you experience in a movie theater.
•
– Skip to your favorite parts of movies
– on-screen index
– Play audio CDs
– DVD players are compatible with audio CDs.
– Watch movies in different picture formats
– DVD movies have both the letterbox format, which fits widescreen TVs, and the standard TV size format.
– Watch movies with subtitles or in a different language
– DVD movies may have several soundtracks on them, and they may provide subtitles in different languages
43

A. DVD-ROM
– first DVD standard and a read-only format .
– With MPEG-2 and Dolby Digital Surround Sound playback capabilities, it is ideal for full-length feature films and computer games with advanced graphics.
– also for access to large amounts of data.
B. DVD-R
– write-once
– for authoring and testing DVD titles, limited distribution DVD publishing.
– Single-sided DVD-R discs store 3.9GB of data.
– two additional standards :
• DVD-RG for general use,
• DVD-RA for authoring, which is used for mastering
• DVD video or data and is not typically available to the general public.
44

C. DVD-RAM
– rewritable function.
– 2.6GB, 4.7GB or 9.4GB (double-sided))
• For applications as data back up, document archiving, multimedia titles and presentations.
– to record and re-record on one disc over 100,000 times
– is compatible only with devices manufactured by the companies that support the DVD-RAM format.
• DVD-RAM discs are typically housed in cartridges.
D. DVD-RW
– rewritable version of DVD-R, 4.7GB per disk.
– an authoring tool as well as for archiving data.
– uses DVD-R media, but is rewriteable up to 1000 times.
– DVD-RW records data sequentially
– DVD-RAM provides random access to recorded data.
45

E. DVD-Audio
–
–
– read-only optical disk for playback of high-quality audio.
– It supports bit depths up to 24-bit and sample rates up to 192 kHz, while CD audio is 16-bit, 44.1 kHz .
Supporting a wide range of digital audio options, offer consumers a superior listening experience.
F . DVD-Video
– a consumer video format used to store digital video on DVD
(DVD-ROM) discs.
– using the DVD-Video specification require a DVD drive and an MPEG-2 decoder (e.g. a DVD player, or a DVD computer drive with a software DVD player).
– Commercial DVD movies are encoded using a combination of MPEG-2 compressed video and audio of varying formats.
– Each DVD-Video disc contains one or more region codes , denoting the area(s) of the world in which distribution and playback are intended.
46

F) DVD-R DL
– ( DL stands for Dual Layer ),
– also called DVD-R9 , is a derivative of the DVD-R format standard.
DVD-R DL discs hold 8.54 GB by utilizing two individual recordable dye layers on a single-sided DVD disc.
–
Dual Layer is more commonly called Double Layer in the consumer market,. Discs can be read in many DVD devices (older units are less compatible) and can only be written using DVD-R DL compatible recorders.
H) DVD-AR
–
DVD-AR DL is a recordable version of DVD-Audio.
I) HD-DVD
– HD DVD or High-Definition Digital Versatile Disc is a high-density optical disc format designed for the storage of data and high-definition video.
–
It has a single-layer capacity of 15 GB, and a dual-layer capacity of
30 GB.
47

A) DVD+R
– can record up to 4.7 GB single-layered/single-sided
DVD+R disc, at up to 16x speed.
– can record only once.
B) DVD+RW
– can record up to 4.7 GB at up to 16x speed.
– can be overwritten several times. It does not need special "pre-pits" or finalization to be played in a DVD player.
C) DVD+R DL
– (also called DVD+R9) is a derivate of DVD+R that uses dual-layer recordable discs to store up to 8.5 GB of data.
48

also known as Blu-ray or BD
- is an optical disc storage media format
- main uses are high-definition video and data storage .
- same dimensions as a standard DVD or CD.
blue-violet laser isused to read and write the disc .
- Because of its shorter wavelength (405 nm), substantially more data can be stored on a Blu-ray Disc than on the DVD format, which uses a red (650 nm) laser.
- A dual layer Blu-ray Disc can store 50 GB , almost six times the capacity of a dual layer DVD.
49

http://www.blu-ray.com/media/ http://en.wikipedia.org/wiki/Blu-ray_Disc
50

- High Definition Television Recording
- High Definition Video Distribution
- High Definition Camcorder Archiving
- Mass Data Storage
- Digital Asset Management and Professional
Storage
-PlayStation 3 games
51

• Blu-ray Disc recordable refers to two optical disc formats that can be recorded with an optical disc recorder.
• BD-R discs can be written to once, whereas BD-RE can be erased and rerecorded multiple times.
•Huge storage capacity enables best picture and sound.
52

Blu-ray Disc increases DVD capacity by five to ten times. This is due, among other reasons, to the usage of a blue instead of a red laser and improved lens specification , allowing for a much smaller focus laser beam which enables the recording of much smaller and higher density pits on the disc.
53

•
Due to the fact that the data layer on a Blu-ray Disc is placed much "closer" to the laser lens than in DVD, there is (1) less distortion resulting in significantly improved tolerances . Hence, (2) more precision and ultra high storage densities are made possible.
•
As a result of Blu-ray Disc being manufactured as a single substrate disc comparable to CD, but unlike DVD ,the manufacturing process does not involve the bonding of two substrates, resulting in (3) less production material, a shorter production time and hence lower production costs per disc .
Fig 21
54

• The BD-ROM specification mandates certain codec compatibilities for both hardware decoders (players) and the movie-software (content). For video, all players are required to support MPEG-2 , H.264/MPEG-4 AVC , and SMPTE
VC-1 .
[55]
• MPEG-2 is the codec used on regular DVDs , which allows backwards compatibility .
•
MPEG-4 AVC was developed by MPEG and VCEG .
• VC-1 is a codec that was mainly developed by Microsoft.
•
BD-ROM titles with video must store video using one of the three mandatory codecs. Multiple codecs on a single title are allowed.
•
The choice of codecs affects the producer's licensing/royalty costs, as well as the title's maximum runtime, due to differences in compression efficiency.
• Discs encoded in MPEG-2 video typically limit content producers to around two hours of high-definition content on a single-layer (25 GB) BD-ROM.
•
The more advanced video codecs (VC-1 and MPEG-4 AVC) typically achieve a video runtime twice that of MPEG-2, with comparable quality.
55

A
B
C
56

• Blu-ray Discs may be encoded with a region code, intended to restrict the area of the world in which they can be played, similar in principle to the DVD region codes, although the used geographical regions differ.
• Blu-ray Disc players sold in a certain region may only play discs encoded for that region. This is primarily used for market segmentation, or price discrimination, but it also allows motion picture studios to control the various aspects of a release (including content and release date) according to the region .
• Discs may also be produced without region coding, so they can be played on all devices. The countries of the major
Blu-ray manufacturers (Japan, Malaysia, South Korea, etc.) are in the same region as the Americas. As of late
2008, almost 70% of all released discs were region-free
57

1.
What is another name for CDROM?
2. What is the difference between “pits” and “bumps” on the disk?
3. Which technology does CD RW apply?
4. Name the two phases of a CD RW disk phase change compound.
5. What is DVD originally known as?
6. Name three types of DVD layer format and indicate the capacity of each format.
7. Name the parts of the CDROM drives and state their functions?
8. What are the advantages of DVD against CDROM?
9. Name the different types of DVD media?
10. Briefly explain the differences of DVD-ROM and DVD-RAM.
58

• Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products.
• It is used more as a hard drive than as RAM.
• It is a solid state storage device .
• Solid state means that there are no moving parts -- everything is electronic instead of mechanical .
• Examples of flash memory:
– computer's BIOS chip
– PDAs (personal digital assistants)
– laptop computers
– digital audio players
– digital cameras and mobile phones
– Memory cards for video game consoles
59

• Basic Principles
– a type of EEPROM chip.
– works faster than traditional EEPROMs because it erases a block or the entire chip, and then rewrites it .
– Flash RAM needs power to maintain its contents, Q14
– Flash memory will maintain its data without any external source of power . (non volatile) Q14
• Removable Flash Memory Cards (Q15)
– Secure Digital (SD)
– CompactFlash (CF)
– Memory Stick (MS)
– MultiMediaCard (MMC)
– xD-Picture Card (xD)
– memory cards for video game systems.
– SmartMedia (SM)
60

• Reasons to use removable Flash
Memory Cards
– Flash memory is noiseless.
– It allows faster access.
– It is smaller in size.
– It is lighter.
– It has no moving parts.
• Why don't we use Flash memory for everything?
– The reason is the cost per megabyte for a hard disk is drastically cheaper, and the capacity is substantially more.
61

PC card
Fig 25
62

• The solid-state floppy-disk card (SSFDC), better known as SmartMedia, was originally developed by Toshiba.
• available in capacities ranging from 2 MB to 128 MB .
• approximately 45 mm long, 37 mm wide and less than 1 mm thick.
• erase, write and read memory in small blocks (256- or 512-byte increments).
• capable of fast, reliable performance while allowing you to specify which data to keep.
• small, lightweight and easy to use .
• less rugged than other forms of removable solid-state storage, so you should be very careful when handling and storing them.
• http://en.wikipedia.org/wiki/SmartMedia
Fig 26
63

• A plane electrode is connected to the
Flash-memory chip by bonding wires .
• The Flash-memory chip, plane electrode and bonding wires are embedded in a resin using a technique called over-molded thin package (OMTP).
• This allows everything to be integrated into a single package without soldering.
• The OMTP module is glued to a base card to create the actual card.
• Power and data are carried by the electrode to the Flash-memory chip when the card is inserted into a device.
• Looking at the card with the electrode facing up, if the notched corner is on the left side, the card needs 5 volts. If the notch is on the right side, it requires 3.3 volts.
Fig 27
64

65

• CompactFlash cards were developed by Sandisk in 1994, and they are different from SmartMedia cards :
• They are thicker.
• They utilize a controller chip.
• It consists of a small circuit board with Flash-memory chips and a dedicated controller chip, all encased in a rugged shell.
• CF cards are 43 mm wide and 36 mm long, and come in two thicknesses: Type I cards are 3.3 mm thick, and Type II cards are 5.5 mm thick.
• It will operate at either 3.3 v or 5 v.
• The increased thickness allows for greater storage capacity range from 8 MB to 64 GB .
• The onboard controller can increase performance , particularly on devices that have slow processors. (adv)
•The case and controller chip add size, weight and complexity to CF card when compared to SmartMedia card.
(disadv)
Fig 29
66

•The fastest way to get the digicam's images from a flash memory card is to use one of the readily available card readers.
•The most common type are made for PCs and connect to the USB port.
• It has single and dual slot USB
1.1 and 2.0 models for CF I/II,
SmartMedia, SD/MMC, Memory
Stick/MS Pro and xD-Picture Cards.
Fig 30
68

• invented by Trek 2000 of Singapore.
• removable solid state flash memory storage device for notebook and desktop computers.
• a solid state device, it has no mechanical parts, can withstand shocks and vibrations during operation .
• a NAND-type flash memory data storage device integrated with a USB (universal serial bus) connector .
• USB flash drives are typically removable and rewritable.
• Any file type can be stored, for example multimedia presentations, accounting, video and
MP3.
Fig 31
69

Features****$$$$
• 64 MB to 128 GB storage capacities
• Uses USB port (USB 1.1 or 2.0) to transfer data
• Weighs 12-30g no extras needed - no drives, cables or power plugs
• Powered by PC - requires no external power supply.
• Disk-write protection switch
• Simple driver software or driverless versions
• Password or fingerprint data security
Fig 31
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1 USB connector
2 USB mass storage controller device
3 Test points
4 Flash memory chip
5 Crystal oscillator
6 LED
7 Write-protect switch
8 Space for second flash memory chip
Fig 26 http://en.wikipedia.org/wiki/USB_flash_drive
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Card family
Standards organizatio ns
Varietie s
Ent ry dat e
I
CompactFlas h
SanDisk 1994
II
Picture Major features
Thinner (3.3 mm), flash based only, sizes available up to 64 GB
Thicker (5.0 mm), older flash based, but usually
Microdrives , sizes available up to 8 GB
SmartMedia Toshiba 3.3V / 5V 1995
Very thin (0.76 mm), sizes available up to 128 MB
72

http://en.wikipedia.org/wiki/Universal_Serial_Bus
73

Different types of USB connectors from left to right
• 8-pin AGOX connector
• Mini-B plug
• Type B plug
• Type A receptacle
• Type A plug
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• Flash drives are impervious to scratches and dust, and mechanically very robust making them suitable for transporting data from place to place and keeping it readily at hand.
Most personal computers support USB as of 2009.
•
Flash drives also store data densely compared to many removable media. In mid-2008,
64 GB drives became available, with the ability to hold many times more data than a
DVD.
•
Compared to hard drives, flash drives use little power, have no fragile moving parts, and for low capacities are small and light.
•
Flash drives implement the USB mass storage device class so that most modern operating systems can read and write to them without installing device drivers. The flash drives present a simple block-structured logical unit to the host operating system, hiding the individual complex implementation details of the various underlying flash memory devices. The operating system can use any file system or block addressing scheme.
Some computers can boot up from flash drives.
•
Some flash drives retain their memory even after being submerged in water [20], even through a machine wash, although this is not a design feature and not to be relied upon.
Leaving the flash drive out to dry completely before allowing current to run through it has been known to result in a working drive with no future problems. Channel Five's
Gadget Show cooked a flash drive with propane, froze it with dry ice, submerged it in various acidic liquids, ran over it with a jeep and fired it against a wall with a mortar. A company specializing in recovering lost data from computer drives managed to recover all the data on the drive. [21] All data on the other removable storage devices tested, using optical or magnetic technologies, were destroyed.
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• Like all flash memory devices, flash drives can sustain only a limited number of write and erase cycles before failure [22][23] . This should be a consideration when using a flash drive to run application software or an operating system. To address this, as well as space limitations, some developers have produced special versions of operating systems (such as Linux in Live USB ) [24] or commonplace applications (such as Mozilla Firefox ) designed to run from flash drives. These are typically optimized for size and configured to place temporary or intermediate files in the computer's main RAM rather than store them temporarily on the flash drive.
•
Most USB flash drives do not include a write-protect mechanism, although some have a switch on the housing of the drive itself to keep the host computer from writing or modifying data on the drive.
Write-protection makes a device suitable for repairing virus -contaminated host computers without risk of infecting the USB flash drive itself.
• A drawback to the small size is that they are easily misplaced, left behind, or otherwise lost. This is a particular problem if the data they contain are sensitive (see data security ). As a consequence, some manufacturers have added encryption hardware to their drives -- although software encryption systems achieve the same thing, and are universally available for all USB flash drives. Others just have the possibility of being attached to keychains, necklaces and lanyards.
• Compared to other portable storage device, for example external hard drives, USB flash drives have a high price per unit of storage and are only available in comparatively small capacities; but hard drives have a higher minimum price, so in the smaller capacities (16 GB and less), USB flash drives are much less expensive than the smallest available hard drives.
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MMC 1997
MultiMediaCa rd
Siemens AG ,
SanDisk
RS-MMC 2003
MMCmobi le /
MMCplus
2005
MMCmicr o
2005
Thin and small (24 mm x 32 mm x 1.4 mm), sizes available up to 4 GB
Compact size (24 mm × 18 mm × 1.4 mm), sizes available up to 2 GB
Compact size (24 mm × 18 mm × 1.4 mm), faster, optional DRM, sizes available up to 2 GB
Sub compact size (14 mm ×
12 mm × 1.1 mm), optional
DRM,
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Standard 1998
Memory Stick S ony/SanDisk PRO 2003
Duo 2003
PRO Duo
2002
-06
PRO-HG
Duo
2007
-08
Micro
(M2)
2006
-02
Thin and narrow (50 mm x
21.5 mm x 2.8 mm), optional DRM, available up to 128 MB
Thin and narrow (50 mm x
21.5 mm x 2.8 mm), faster, optional DRM, Memory up to 4 GB
Compact size (31 mm x 20 mm x 1.6 mm), optional
DRM, Memory up to 128
MB
Compact size (31 mm x 20 mm x 1.6 mm), optional
DRM, available up to 16
GB
Compact size (31 mm x 20 mm x 1.6 mm), faster , optional DRM, available up to 4 GB
Sub compact size (15 mm x 12.5 mm x 1.2 mm), optional DRM, available up to 8 GB
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Secure
Digital
SD 1999 miniSD 2003 microSD 2005
Panasonic,
SanDisk,
Toshiba
SDHC 2006 miniSDH
C
2007 microSDH
C
2007
Small (32 mm × 24 mm ×
2.1 mm), DRM, sizes available up to 4 GB
Compact size (21.5 mm x
20 mm x 1.4 mm), DRM, available up to 2 GB
Sub compact size (11 mm x 15 mm x 1 mm), DRM, available up to 4 GB
Physically the same as SD but offers higher capacity and transfer speed, available up to 32 GB
Physically the same as miniSD but offers higher capacity and transfer speed, available up to 8
GB
Physically the same as microSD but offers higher capacity and transfer speed, available up to 16
GB
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xD
Olympus,
Fujifilm
Standard
2002
-07
Type M 2005
Type H 2005
USB flash drive
Various
USB 1.1 /
2.0
2001
Thin and small (20 mm ×
25 mm × 1.78 mm), available up to 512 MB [1]
Thin and small (20 mm ×
25 mm × 1.78 mm) but slower read / write, available up to 2 GB [2]
Thin and small (20 mm ×
25 mm × 1.78 mm) and faster than previous two versions, available up to 2
GB [3]
Universally compatible across all computer platforms, but larger size suits them better to file transfer/storage instead of use in portable devices, available up to 64 GB
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ThumbDrive MUSIC, a combination of patented ThumbDrive technologies with digital audio playback functionality to create a self-contained data storage device and portable music player.
Audio
ThumbDrive MUSIC is able to offers 12hours of playback with a single AAA alkaline battery. Furthermore, it can plays WMA and
MP3 tracks and also twice the versatile data storage device.
Removable Drive
When the player is removed from the battery pack and plug into any computer with a USB port, it acts like a removable drive similar to the ThumbDrive.
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1.
Which hard disk technology introduced by IBM provides highest areal densities?
2.
Name two types of removable storage devices using magnetic recording principles.
3.
How does a microdrive integrate with a variety of handheld devices?
4.
Name two types of removable solid state flash memory storage devices.
5.
What is solid state technology?
6.
What is the difference between flash RAM and flash memory?
7.
Give two advantages of the CompactFlash cards as compared to SmartMedia cards.
8.
State three advantages of thumb drive.
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•There is nothing that can replace backup to prevent data loss and avoid expensive recovery.
•Backup simply means you are keeping at least one copy of the original data, preferably not in the same disk media.
•If your data is important, an un-interrupt power supply protects your computer and data during a power failure.
•The spare battery in the ups gives you ample time to save your documents and shut down windows properly so that you will not lose any files or damage any hardware components.
•Keep the machine in a dry, shaded, dust-free and well-ventilated area never leave your computer near places where it is directly exposed to rain, sun or humidity. Such conditions have the tendency to cause rusting and damage to your hardware parts.
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•Avoid moving your computer or notebook when it is in operation . You definitely would not wish for your power cord to fall off and cause a data corruption and physical damage to your hard disk such as a head crash while working on a project.
Vibration or impact may also cause your hard disk to crash.
•Perform disk defragmentation once every few months. Such process ensures the data is arranged more contiguously and is easier for access or recovery. Clean up temporary files and unused files from time to time. This helps to keep your hard disk on top form.
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• Anti-virus software is designed to protect your computer against malicious computer viruses, trojan and other malicious-ware. Some virus infections can delete, modify your data secretly causing your computer to crash. Most viruses nowadays spread through internet and it is a real must to have a secure Anti-virus software with firewalls.
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You can protect yourself against viruses with a few simple steps:
– a more secure operating system like UNIX .
– Buy an Anti-virus software is a nice safeguard.
Be sure to update your Anti-virus software with the latest patch and signature files for maximum security.
Patch, a fix for a software program where the actual binary executable and related files are modified.
Signature files is a technique applied for document retrieval. The idea behind Signature files is to create a quick and dirty filter that will keep all the documents that match to the query and hopefully a few ones that do not. The way this is done is by creating for each file a signature, typically a hash coded version. One method is superimposed coding. A postprocessing step is done to discard the false alarms. This structure since in most cases is inferior to inverted files in terms of speed, size and functionality, is not used much. However, with proper parameters it can beat the inverted files in certain environments.
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• If you simply avoid programs from unknown sources
(like the Internet), and instead stick with commercial software purchased on CDs, you eliminate almost all of the risk from traditional viruses.
• You should make sure that Macro Virus Protection is enabled in all Microsoft applications, and you should
NEVER run macros in a document unless you know what they do. There is seldom a good reason to add macros to a document, so avoiding all macros is a great policy.
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Open the Options dialog from the Tools menu in
Microsoft Word and make sure that Macro Virus
Protection is enabled. Newer versions of Word allow you to customize the level of macro protection you use.
88

• You should never double-click on an e-mail attachment that contains an executable.
– Attachments that come in as Word files (.DOC), spreadsheets
(.XLS), images (.GIF), etc., are data files and they can do no damage (noting the macro virus problem in Word and Excel documents mentioned above).
– However, some viruses can now come in through .JPG graphic file attachments.
– A file with an extension like EXE, COM or VBS is an executable, and an executable can do any sort of damage it wants. Once you run it, you have given it permission to do anything on your machine. The only defense is never to run executables that arrive via e-mail.
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