Physical Characteristics of Disks

8/9/2019 Physical Characteristics of Disks

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Physical Characteristics of Disks

1. The storage capacity of a single disk ranges from 10MB to 10GB. A typical commercialdatabase may require hundreds of disks.

2. igure 10.2 sho!s a mo"ing#head disk mechanism.

o $ach disk platter has a flat circular shape. %ts t!o surfaces are co"ered !ith a

magnetic material and information is recorded on the surfaces. The platter of hard disks are made from rigid metal or glass& !hile floppy disks are made fromfle'ible material.

o The disk surface is logically di"ided into tracks& !hich are subdi"ided into

sectors. A sector ("arying from )2 bytes to *0+, bytes& usually -12 bytes is thesmallest unit of information that can be read from or !ritten to disk. There are *#)2 sectors per track and 20#1-00 tracks per disk surface.

o The arm can be positioned o"er any one of the tracks.

o The platter is spun at high speed.

o To read information& the arm is positioned o"er the correct track.

o /hen the data to be accessed passes under the head& the read or write operation

is performed.

). A disk typically contains multiple platters (see igure 10.2. The read#!rite heads of allthe tracks are mounted on a single assembly called a disk arm& and mo"e together.

o Multiple disk arms are mo"ed as a unit by the actuator.

o $ach arm has t!o heads& to read disks abo"e and belo! it.

o The set of tracks o"er !hich the heads are located forms a cylinder.

o This cylinder holds that data that is accessible !ithin the disk latency time.

o %t is clearly sensible to store related data in the same or adacent cylinders.

*. isk platters range from 1.3 to 1*3 in diameter& and -314* and )3142 disks dominate dueto the lo!er cost and faster seek time than do larger disks& yet they pro"ide high storagecapacity.


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-. A disk controller interfaces bet!een the computer system and the actual hard!are of thedisk dri"e. %t accepts commands to r4! a sector& and initiate actions. isk controllers alsoattach checksums to each sector to check read error.

,. Remapping of bad sectors5 %f a controller detects that a sector is damaged !hen the disk

is initially formatted& or !hen an attempt is made to !rite the sector& it can logically mapthe sector to a different physical location.

6. 787% (Small Computer System Interconnect is commonly used to connect disks to 98sand !orkstations. Mainframe and ser"er systems usually ha"e a faster and moree'pensi"e bus to connect to the disks.

. :ead crash5 !hy cause the entire disk failing (;.

+. A fixed dead disk has a separate head for each track ## "ery many heads& "ery e'pensi"e. Multiple disk arms5 allo! more than one track to be accessed at a time. Both !ere used in

high performance mainframe systems but are relati"ely rare today.

The standard RAID levels are a basic set of


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• 7 RAID 6

o 7.1 Performance (speed)

o 7.2 Implementaton

7.2.1 Comp!tn" part#

• $ Comparson

• % &on'standard RAID leels and non'RAID dre arctect!res

• 10 &otes

• 11 References

• 12 *+ternal ln,s

RAID 0

Da"ram of a RAID 0 set!p

A RAID 0 (also kno!n as a stripe set or striped volume splits data e"enly across t!o or more

disks (striped& !ithout parity information and !ith speed as the intended goal.


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The diagram sho!s ho! the data is distributed into A x stripes to the disks. Accessing the stripes

in the order A1& A2& A)& ... pro"ides the illusion of a larger and faster dri"e. nce the stripe si=e

is defined on creation it needs to be maintained at all times.

Performance


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across all members of the set and !ill reside in the same location. 7o& any %4 operation requires

acti"ity on e"ery disk and usually requires synchroni=ed spindles.

This makes it suitable for applications that demand the highest transfer rates in long sequential

reads and !rites& for e'ample uncompressed "ideo editing. Applications that make small reads

and !rites from random disk locations !ill get the !orst performance out of this le"el.?6@

The requirement that all disks spin synchronously& a.k.a. lockstep& added design considerations to

a le"el that didnCt gi"e significant ad"antages o"er other


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3gathered3 and scheduled to the same


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Performance (speed)


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Mathematically& the generator is an element of the field such that is different for each

nonnegati"e satisfying .

%f one data dri"e is lost& the data can be recomputed from P ust like !ith


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&on'standard RAID leels and non'RAID dre arctect!res

@an artcles> &on'standard RAID leels and &on'RAID dre arctect!res

http://en.wikipedia.org/wiki/RAID_5http://en.wikipedia.org/wiki/RAID_5http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-FastHardware-18http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-FastHardware-18http://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/RAID_6http://en.wikipedia.org/wiki/RAID_6http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-FastHardware-18http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-FastHardware-18http://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/RAID_10http://en.wikipedia.org/wiki/RAID_10http://en.wikipedia.org/wiki/RAID_10http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-19http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-20http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-NonDegenerate-15http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-IdenticalRate-16http://en.wikipedia.org/wiki/Non-standard_RAID_levelshttp://en.wikipedia.org/wiki/Non-RAID_drive_architectureshttp://en.wikipedia.org/wiki/RAID_5http://en.wikipedia.org/wiki/RAID_5http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-FastHardware-18http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-FastHardware-18http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-FastHardware-18http://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/RAID_6http://en.wikipedia.org/wiki/RAID_6http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-FastHardware-18http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-FastHardware-18http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-FastHardware-18http://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/RAID_10http://en.wikipedia.org/wiki/RAID_10http://en.wikipedia.org/wiki/RAID_10http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-19http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-20http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-NonDegenerate-15http://en.wikipedia.org/wiki/Standard_RAID_levels#cite_note-IdenticalRate-16http://en.wikipedia.org/wiki/Non-standard_RAID_levelshttp://en.wikipedia.org/wiki/Non-RAID_drive_architectures


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Alternati"es to the abo"e designs include nested 4B%G& and MA%.

9T%8AD M$M


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%n 200*& !orld!ide sales of 8 audio& 8#


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• 4 @an!fact!re

• 5 rtale compact dscs

o 5.1 Recordale CD

o 5.2 Rertale CD

5.2.1 Fpeed

• 6 Cop# protecton

• 7 Fee also

• $ References

• % 8!rter readn"

• 10 *+ternal ln,s

stor#

The 8ompact isc is an e"olution of Daserisc technology. 9rototypes !ere de"eloped by

9hilips and 7ony independently from the mid#to#late 1+60s.?)@ The t!o companies then

collaborated to produce a standard format and related player technology !hich !as made

commercially a"ailable in 1+2.

D"tal a!do optcal dsc protot#pes

American in"entor James T.


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Mean!hile& 7ony first publicly demonstrated an optical digital audio disc in 7eptember 1+6,. %n

7eptember 1+6& the company demonstrated an optical digital audio disc !ith a 1-0 minute

playing time& **&0-, := sampling rate& 1,#bit linear resolution& and cross#interlea"ed error

correction codeEspecifications similar to those later settled upon for the standard 8ompact isc

format in 1+0. Technical details of 7onyCs digital audio disc !ere presented during the ,2nd

A$7 8on"ention& held on March 1)H1,& 1+6+& in Brussels.?@ Just before that& on March & 1+6+9hilips publicly demonstrated a prototype of an optical digital audio disc at a press conference

called 39hilips %ntroduce 8ompact isc3?+@ in $indho"en& >etherlands.?10@ Thirty years later& on

March ,& 200+& 9hilips recei"ed an %$$$ Milestone a!ard !ith the follo!ing citation5 3n

March 1+6+& >.Q. 9hilipsC Gloeilampenfabrieken demonstrated for the international press a

8ompact isc Audio 9layer. The demonstration sho!ed that it is possible by using digital optical

recording and playback to reproduce audio signals !ith superb stereo quality. This research at

9hilips established the technical standard for digital optical recording systems.3?11@

7ony e'ecuti"e >orio hga& !ho later became the 8$ and chairman of 7ony& !as con"inced of

the formatCs commercial potential and pushed further de"elopment despite !idespreadskepticism.?12@

Collaoraton and standardaton

Dater in 1+6+& 7ony and 9hilips set up a oint task force of engineers to design a ne! digital

audio disc. Ded by Sees 7chouhamer %mmink and Toshitada oi& the research pushed for!ard

laser and optical disc technology that began independently by the t!o companies.?+@ After a year

of e'perimentation and discussion& the task force produced the Red #ook 8#A standard. irst

published in 1+0& the standard !as formally adopted by the %$8 as an international standard in

1+6& !ith "arious amendments becoming part of the standard in 1++,.

9hilips contributed the general manufacturing process& based on "ideo Daserisc technology.

9hilips also contributed eight#to#fourteen modulation ($M& !hich offers a certain resilience to

defects such as scratches and fingerprints& !hile 7ony contributed the error#correction method&

8%


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Mean!hile& !ith the ad"ent and popularity of digital audio formats& such as the 2-, kbit m*a&

sales of 8s began dropping in the 2000s. or e'ample& during the eight#year period ending in

200& despite o"erall gro!th in music sales and one anomalous year of increase& maor#label 8

sales declined o"erall by 20R ?2@ although independent and %K music sales may be tracking

better according to figures released March )0& 200+ and 8s still continue to sell greatly.?2+@

P#scal detals

Da"ram of CD la#ers.

A. A pol#caronate dsc la#er as te data encoded # !sn" !mps.

:. A sn# la#er reNects te laser.

C. A la#er of lacO!er protects te sn# la#er.

D. Art/or, s screen prnted on te top of te dsc.

*. A laser eam reads te CD and s reNected ac, to a sensor /c conerts tnto electronc data

A 8 is made from 1.2 millimetres (0.0*6 in thick& polycarbonate plastic and !eighs 1-H

20 grams.?)0@ rom the center out!ard& components are5 the center spindle hole (1- mm& the

first#transition area (clamping ring& the clamping area (stacking ring& the second#transition area

(mirror band& the program (data area& and the rim. The inner program area occupies a radius

from 2- to - mm.

A thin layer of aluminium or& more rarely& gold is applied to the surface making it reflecti"e. The

metal is protected by a film of lacquer normally spin coated directly on the reflecti"e layer. The

label is printed on the lacquer layer& usually by screen printing or offset printing.

8 data is represented as tiny indentations kno!n as 3pits3& encoded in a spiral track moulded

into the top of the polycarbonate layer. The areas bet!een pits are kno!n as 3lands3. $ach pit is

appro'imately 100 nm deep by -00 nm !ide& and "aries from -0 nm to ).- m in length. The

distance bet!een the tracks& the pitch& is 1.- m.

http://en.wikipedia.org/wiki/Audio_formathttp://en.wikipedia.org/wiki/M4ahttp://en.wikipedia.org/wiki/Compact_disc#cite_note-AutoMR-11-28http://en.wikipedia.org/wiki/Compact_disc#cite_note-AutoMR-12-29http://en.wikipedia.org/wiki/Compact_disc#cite_note-AutoMR-12-29http://en.wikipedia.org/wiki/Screen_printinghttp://en.wikipedia.org/wiki/Polycarbonatehttp://en.wikipedia.org/wiki/Compact_disc#cite_note-AutoMR-13-30http://en.wikipedia.org/wiki/Spin_coatedhttp://en.wikipedia.org/wiki/Screen_printinghttp://en.wikipedia.org/wiki/Screen_printinghttp://en.wikipedia.org/wiki/Offset_printinghttp://en.wikipedia.org/wiki/Offset_printinghttp://en.wikipedia.org/wiki/Nanometrehttp://en.wikipedia.org/wiki/Micrometrehttp://en.wikipedia.org/wiki/Audio_formathttp://en.wikipedia.org/wiki/M4ahttp://en.wikipedia.org/wiki/Compact_disc#cite_note-AutoMR-11-28http://en.wikipedia.org/wiki/Compact_disc#cite_note-AutoMR-12-29http://en.wikipedia.org/wiki/Screen_printinghttp://en.wikipedia.org/wiki/Polycarbonatehttp://en.wikipedia.org/wiki/Compact_disc#cite_note-AutoMR-13-30http://en.wikipedia.org/wiki/Spin_coatedhttp://en.wikipedia.org/wiki/Screen_printinghttp://en.wikipedia.org/wiki/Offset_printinghttp://en.wikipedia.org/wiki/Nanometrehttp://en.wikipedia.org/wiki/Micrometre


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7canning "elocity is 1.2H1.* m4s (constant linear "elocity H equi"alent to appro'imately -00


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9hilharmonic rchestraCs recording of Beetho"enCs >inth 7ymphony on one disc.?12@ This

diameter has been adopted by subsequent formats& including 7uper Audio 8& Q& : Q&

and Blu#ray isc. 0 mm discs (3Mini 8s3 !ere originally designed for 8 singles and can

hold up to 2* minutes of music or 210 MB of data but ne"er became popular.?citation needed @ Today&

nearly e"ery single is released on a 120 mm 8& called a Ma'i single.?citation needed @

The hole in the middle of the disc is e'actly the si=e of a ubbelte the 10 cent piece of the

utchVguilder . The team designing the disk at philips used it in their prototype and it !as ne"er

changed.

>o"elty 8s are also a"ailable in numerous shapes and si=es& and are used chiefly for marketing.

A common "ariant is the 3business card3 8& a single !ith portions remo"ed at the top and

bottom making the disk resemble a business card.

!ysical si"e Audio

#apacity

#D$R%M Data

#apacity De&nition

120 mm 74$0 mn 650700 @: Ftandard se

$0 mm 2124 mn 1$5210 @: @n'CD se

$0+54 mm $0+64 mm S6 mn 10'65 @: T:!sness cardT se

-o"cal formats

A!do CD@an artcle> Compact Dsc D"tal A!do

The logical format of an audio 8 (officially 8ompact isc igital Audio or 8#A is

described in a document produced in 1+0 by the formatCs oint creators& 7ony and 9hilips. Thedocument is kno!n colloquially as the Red #ook 8#A after the color of its co"er. The format

is a t!o#channel 1,#bit 98M encoding at a **.1 k:= sampling rate per channel. our#channel

sound !as to be an allo!able option !ithin the Red #ook format& but has ne"er been

implemented. Monaural audio has no e'isting standard on a Red #ook 8 mono#source material

thus is usually presented as t!o identical channels in a standard Red #ook stereo track (i.e.

mirrored mono an M9) 8& ho!e"er& can ha"e audio file formats !ith mono sound.

8#Te't is an e'tension of the Red #ook specification for audio 8 that allo!s for storage of

additional te't information (e.g.& album name& song name& artist on a standards#compliant audio

8. The information is stored either in the lead#in area of the 8& !here there is roughly fi"ekilobytes of space a"ailable& or in the subcode channels < to / on the disc& !hich can store

about )1 megabytes.

8ompact isc W Graphics is a special audio compact disc that contains graphics data in addition

to the audio data on the disc. The disc can be played on a regular audio 8 player& but !hen

played on a special 8WG player& can output a graphics signal (typically& the 8WG player is

hooked up to a tele"ision set or a computer monitor these graphics are almost e'clusi"ely used

http://en.wikipedia.org/wiki/London_Philharmonic_Orchestrahttp://en.wikipedia.org/wiki/London_Philharmonic_Orchestrahttp://en.wikipedia.org/wiki/Beethoven's_Ninth_Symphonyhttp://en.wikipedia.org/wiki/Compact_disc#cite_note-Ohgaobituary-12http://en.wikipedia.org/wiki/Super_Audio_CDhttp://en.wikipedia.org/wiki/DVDhttp://en.wikipedia.org/wiki/HD_DVDhttp://en.wikipedia.org/wiki/HD_DVDhttp://en.wikipedia.org/wiki/Blu-ray_Dischttp://en.wikipedia.org/wiki/Mini_CDhttp://en.wikipedia.org/wiki/Single_(music)http://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Maxi_singlehttp://en.wikipedia.org/wiki/Maxi_singlehttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Dubbeltjehttp://en.wikipedia.org/wiki/Dubbeltjehttp://en.wikipedia.org/wiki/Dutch_guilderhttp://en.wikipedia.org/wiki/Dutch_guilderhttp://en.wikipedia.org/wiki/Megabytehttp://en.wikipedia.org/wiki/Compact_Disc_Digital_Audiohttp://en.wikipedia.org/wiki/Compact_Disc_Digital_Audiohttp://en.wikipedia.org/wiki/Compact_Disc_Digital_Audiohttp://en.wikipedia.org/wiki/Pulse-code_modulationhttp://en.wikipedia.org/wiki/44.1_kHzhttp://en.wikipedia.org/wiki/44.1_kHzhttp://en.wikipedia.org/wiki/Sampling_ratehttp://en.wikipedia.org/wiki/Sampling_ratehttp://en.wikipedia.org/wiki/Four-channel_Compact_Disc_Digital_Audiohttp://en.wikipedia.org/wiki/Four-channel_Compact_Disc_Digital_Audiohttp://en.wikipedia.org/wiki/Monauralhttp://en.wikipedia.org/wiki/Monauralhttp://en.wikipedia.org/wiki/Mono_sound#Mirrored_monohttp://en.wikipedia.org/wiki/MP3_CDhttp://en.wikipedia.org/wiki/CD-Texthttp://en.wikipedia.org/wiki/Lead-in_(CD)http://en.wikipedia.org/wiki/Compact_Disc_subcodehttp://en.wikipedia.org/wiki/Compact_Disc_subcodehttp://en.wikipedia.org/wiki/Compact_Disc_%2B_Graphicshttp://en.wikipedia.org/wiki/London_Philharmonic_Orchestrahttp://en.wikipedia.org/wiki/Beethoven's_Ninth_Symphonyhttp://en.wikipedia.org/wiki/Compact_disc#cite_note-Ohgaobituary-12http://en.wikipedia.org/wiki/Super_Audio_CDhttp://en.wikipedia.org/wiki/DVDhttp://en.wikipedia.org/wiki/HD_DVDhttp://en.wikipedia.org/wiki/Blu-ray_Dischttp://en.wikipedia.org/wiki/Mini_CDhttp://en.wikipedia.org/wiki/Single_(music)http://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Maxi_singlehttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Dubbeltjehttp://en.wikipedia.org/wiki/Dutch_guilderhttp://en.wikipedia.org/wiki/Megabytehttp://en.wikipedia.org/wiki/Compact_Disc_Digital_Audiohttp://en.wikipedia.org/wiki/Compact_Disc_Digital_Audiohttp://en.wikipedia.org/wiki/Pulse-code_modulationhttp://en.wikipedia.org/wiki/44.1_kHzhttp://en.wikipedia.org/wiki/Sampling_ratehttp://en.wikipedia.org/wiki/Four-channel_Compact_Disc_Digital_Audiohttp://en.wikipedia.org/wiki/Four-channel_Compact_Disc_Digital_Audiohttp://en.wikipedia.org/wiki/Monauralhttp://en.wikipedia.org/wiki/Mono_sound#Mirrored_monohttp://en.wikipedia.org/wiki/MP3_CDhttp://en.wikipedia.org/wiki/CD-Texthttp://en.wikipedia.org/wiki/Lead-in_(CD)http://en.wikipedia.org/wiki/Compact_Disc_subcodehttp://en.wikipedia.org/wiki/Compact_Disc_%2B_Graphics


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to display lyrics on a tele"ision set for karaoke performers to sing along !ith. The 8WG format

takes ad"antage of the channels < through /. These si' bits store the graphics information.

8 W $'tended Graphics (8W$G& also kno!n as 8WIG is an impro"ed "ariant of the

8ompact isc W Graphics (8WG format. Dike 8WG& 8W$G utili=es basic 8# Hdeo CD

Qideo 8 (Q8& Qie! 8& and 8ompact isc digital "ideo is a standard digital format for

storing "ideo media on a 8. Q8s are playable in dedicated Q8 players& most modern Q#

Qideo players& personal computers& and some "ideo game consoles.

The Q8 standard !as created in 1++) by 7ony& 9hilips& Matsushita& and JQ8 and is referred to

as the 'hite #ook standard.

http://en.wikipedia.org/wiki/Karaokehttp://en.wikipedia.org/wiki/CD_%2B_Extended_Graphicshttp://en.wikipedia.org/wiki/Compact_disc#CD_.2B_Graphicshttp://en.wikipedia.org/wiki/Compact_Disc_subcodehttp://en.wikipedia.org/wiki/Super_Audio_CDhttp://en.wikipedia.org/wiki/Optical_dischttp://en.wikipedia.org/wiki/Optical_dischttp://en.wikipedia.org/wiki/Audio_storagehttp://en.wikipedia.org/wiki/Audio_storagehttp://en.wikipedia.org/wiki/High_fidelityhttp://en.wikipedia.org/wiki/Format_warhttp://en.wikipedia.org/wiki/DVD-Audiohttp://en.wikipedia.org/wiki/Backward_compatibilityhttp://en.wikipedia.org/wiki/Musical_Instrument_Digital_Interfacehttp://en.wikipedia.org/wiki/CD-ROMhttp://en.wikipedia.org/wiki/CD-ROMhttp://en.wikipedia.org/wiki/Computer_data_storagehttp://en.wikipedia.org/wiki/Computer_data_storagehttp://en.wikipedia.org/wiki/Video_CDhttp://en.wikipedia.org/wiki/Digital_datahttp://en.wikipedia.org/wiki/DVD-Videohttp://en.wikipedia.org/wiki/DVD-Videohttp://en.wikipedia.org/wiki/Panasonic_Corporationhttp://en.wikipedia.org/wiki/JVChttp://en.wikipedia.org/wiki/Karaokehttp://en.wikipedia.org/wiki/CD_%2B_Extended_Graphicshttp://en.wikipedia.org/wiki/Compact_disc#CD_.2B_Graphicshttp://en.wikipedia.org/wiki/Compact_Disc_subcodehttp://en.wikipedia.org/wiki/Super_Audio_CDhttp://en.wikipedia.org/wiki/Optical_dischttp://en.wikipedia.org/wiki/Audio_storagehttp://en.wikipedia.org/wiki/High_fidelityhttp://en.wikipedia.org/wiki/Format_warhttp://en.wikipedia.org/wiki/DVD-Audiohttp://en.wikipedia.org/wiki/Backward_compatibilityhttp://en.wikipedia.org/wiki/Musical_Instrument_Digital_Interfacehttp://en.wikipedia.org/wiki/CD-ROMhttp://en.wikipedia.org/wiki/CD-ROMhttp://en.wikipedia.org/wiki/Computer_data_storagehttp://en.wikipedia.org/wiki/Video_CDhttp://en.wikipedia.org/wiki/Digital_datahttp://en.wikipedia.org/wiki/DVD-Videohttp://en.wikipedia.org/wiki/DVD-Videohttp://en.wikipedia.org/wiki/Panasonic_Corporationhttp://en.wikipedia.org/wiki/JVC


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"erall picture quality is intended to be comparable to Q:7 "ideo. 9oorly compressed Q8

"ideo can sometimes be lo!er quality than Q:7 "ideo& but Q8 e'hibits block artifacts rather

than analog noise& and does not deteriorate further !ith each use& !hich may be preferable.

)-2'2*0 (or 7% resolution !as chosen because it is half the "ertical& and half the hori=ontal

resolution of >T78 "ideo. )-2'2 is similarly one quarter 9AD47$8AM resolution. Thisappro'imates the (o"erall resolution of an analog Q:7 tape& !hich& although it has double the

number of ("ertical scan lines& has a much lo!er hori=ontal resolution.

F!per Hdeo CD@an artcle> F!per Hdeo CD

7uper Qideo 8 (7uper Qideo 8ompact isc or 7Q8 is a format used for storing "ideo media

on standard compact discs. 7Q8 !as intended as a successor to Q8 and an alternati"e to

Q#Qideo& and falls some!here bet!een both in terms of technical capability and picture

quality.

7Q8 has t!o#thirds the resolution of Q& and o"er 2.6 times the resolution of Q8. ne

8#< disc can hold up to ,0 minutes of standard quality 7Q8#format "ideo. /hile no specific

limit on 7Q8 "ideo length is mandated by the specification& one must lo!er the "ideo bit rate&

and therefore quality& to accommodate "ery long "ideos. %t is usually difficult to fit much more

than 100 minutes of "ideo onto one 7Q8 !ithout incurring significant quality loss& and many

hard!are players are unable to play "ideo !ith an instantaneous bit rate lo!er than )00 to ,00

kilobits per second.

Poto CD

@an artcle> Poto CD

9hoto 8 is a system designed by Sodak for digiti=ing and storing photos on a 8. Daunched in

1++2& the discs !ere designed to hold nearly 100 high quality images& scanned prints and slides

using special proprietary encoding. 9hoto 8s are defined in the #eige #ook and conform to the

8#


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8#i Bridge specification !as added to create 8#i compatible discs than can be accessed by

regular 8# Hn#lDsc

Qinyl isc is the hybrid of a standard Audio 8 and the "inyl record. The "inyl layer on the

discCs label side can hold appro'imately three minutes of music.

@an!fact!re

@an artcle> CD man!fact!rn"

http://en.wikipedia.org/wiki/CD-i_Bridgehttp://en.wikipedia.org/wiki/CD-i_Readyhttp://en.wikipedia.org/wiki/CD-i_Readyhttp://en.wikipedia.org/wiki/Pregap#Computer_data_in_pregaphttp://en.wikipedia.org/wiki/Blue_Book_(CD_standard)http://en.wikipedia.org/wiki/CD-DAhttp://en.wikipedia.org/wiki/CD-DAhttp://en.wikipedia.org/wiki/CD-ROMhttp://en.wikipedia.org/wiki/Session_(CD)http://en.wikipedia.org/wiki/Session_(CD)http://en.wikipedia.org/wiki/Session_(CD)http://en.wikipedia.org/wiki/Blue_Book_(CD_standard)http://en.wikipedia.org/wiki/Blue_Book_(CD_standard)http://en.wikipedia.org/wiki/Blue_Book_(CD_standard)http://en.wikipedia.org/wiki/VinylDischttp://en.wikipedia.org/wiki/Gramophone_recordhttp://en.wikipedia.org/wiki/Gramophone_recordhttp://en.wikipedia.org/wiki/CD_manufacturinghttp://en.wikipedia.org/wiki/CD-i_Bridgehttp://en.wikipedia.org/wiki/CD-i_Readyhttp://en.wikipedia.org/wiki/CD-i_Readyhttp://en.wikipedia.org/wiki/Pregap#Computer_data_in_pregaphttp://en.wikipedia.org/wiki/Blue_Book_(CD_standard)http://en.wikipedia.org/wiki/CD-DAhttp://en.wikipedia.org/wiki/CD-DAhttp://en.wikipedia.org/wiki/CD-ROMhttp://en.wikipedia.org/wiki/Session_(CD)http://en.wikipedia.org/wiki/Blue_Book_(CD_standard)http://en.wikipedia.org/wiki/VinylDischttp://en.wikipedia.org/wiki/Gramophone_recordhttp://en.wikipedia.org/wiki/CD_manufacturing


25/28

Indd!al pts are sle on te mcrometre scale


26/28

o"er the surface. $dge protection lacquer is applied before the disc is finished. The disc can then

be printed and packed.

Manufactured 8s that are sold in stores are sealed "ia a process called 3poly!rapping3 or

shrink !rapping.

The most e'pensi"e part of a 8 is the e!el case. %n 1++-& material costs !ere )0 cents for the

e!el case and 10 to 1- cents for the 8. /holesale cost of 8s !as X0.6- to X1.1-& !hich

retailed for X1,.+.?)*@ n a"erage the store recei"ed )- percent of the retail price& the record

company 26 percent& the artist 1, percent& the manufacturer 1) percent& and the distributor +

percent.?)*@ /hen #track tapes& cassette tapes& and 8s !ere introduced& each !as marketed at a

higher price than the format they succeeded& e"en though the cost to produce the media !as

reduced. This !as done because the apparent "alue increased. This continued from "inyl to 8s

but !as broken !hen Apple marketed M9)s for X0.++& and albums for X+.++. The incremental

cost& though& to produce an M9) is infinitely small.?)-@

rtale compact dscs

Recordale CD

700 @: CD'R ne+t to a mecancal pencl

@an artcle> CD'R


27/28

error correction methods. The design life is from 20 to 100 years& depending on the quality of the

discs& the quality of the !riting dri"e& and storage conditions. :o!e"er& testing has demonstrated

such degradation of some discs in as little as 1 months under normal storage conditions.?),@?)6@

This failure is kno!n as disc rot& for !hich there are se"eral& mostly en"ironmental& reasons.?)1@

The recordable audio 8 is designed to be used in a consumer audio 8 recorder. Theseconsumer audio 8 recorders use 78M7 (7erial 8opy Management 7ystem& an early form of

digital rights management (


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The Red #ook audio specification& e'cept for a simple Canti#copyC statement in the subcode& does

not include any copy protection mechanism. Sno!n at least as early as 2001&?*1@ attempts !ere

made by record companies to market 3copy#protected3 non#standard compact discs& !hich

cannot be ripped& or copied& to hard dri"es or easily con"erted to M9)s. ne maor dra!back to

these copy#protected discs is that most !ill not play on either computer 8#umerous copy#protection systems ha"e been countered by readily

a"ailable& often free& soft!are.

D#D (sometimes e'plained as 3di$ital video disc3 or 3di$ital versatile disc3?-@?,@ is a digital optical disc storage format& in"ented and de"eloped by 9hilips& 7ony& Toshiba& and 9anasonic in1++-. Qs can be played in many types of players& including Q players. Qs offer higherstorage capacity than compact discs !hile ha"ing the same dimensions.

9re#recorded Qs are mass#produced using molding machines that physically stamp data ontothe Q. 7uch discs are kno!n as Q#

Documents

Physical Characteristics of Disks