1 COMPUTER ARCHITECTURE (for Erasmus students) Assoc.Prof. Stasys Maciulevičius Computer Dept.

©S.Maciulevičius Compact Discs The Compact Disc was invented by Sony and Philips in 1981 in order to serve as a high-quality compact audio storage device which allowed for direct access to digital sound tracks

©S.Maciulevičius CD geometry  A CD is an optical disc 12cm in diameter and 1.2 mm thick (its thickness may vary from 1.1 to 1.5 mm) for storing digital information: up to 650 MB of computer data (equivalent to 300,000 typed pages) or 74 minutes of audio data  A circular hole 15mm in diameter is used to centre it on the CD player's surface.

©S.Maciulevičius Operation  The read head is made of a laser which emits a beam of light, and a photoelectric cell which captures the reflected beam  CD players use an infrared laser (with a wavelength of 780 nm), as it is compact and inexpensive

©S.Maciulevičius Operating modes CD has two basic operating modes: Reading at a constant linear velocity (CLV). This was the operating mode of the earliest CD-ROM drives, based on how CD audio players and even old turntables work. When a disc turns, the grooves closer to the centre run more slowly than the grooves on the outer edge, so the read speed (and therefore the speed at which the disc rotates) has to adjust based on the radial position of the read head Reading at a constant angular velocity (CAV) involves adjusting the information density depending on where the data is located, so that the rotation speed is the same at every point on the disc. This means that data density will be lower on the edge of the disc and higher near the centre

©S.Maciulevičius CD standards  There are numerous standards describing the ways in which information must be stored on a compact disc, depending on how it is to be used  These standards are set out in documents called books, each of which has a colour assigned to it  Red book: Developed in 1980 by Sony and Philips, it describes the physical format of a CD and the encoding method for an audio CD. It defines a sample rate of 44.1 kHz and 16-bit resolution (in stereo) for recording audio data

©S.Maciulevičius CD standards  Yellow book: Developed in 1984 in order to describe the physical format for data CDs (CD-ROM for Compact Disc - Read Only Memory). It includes two modes:  CD-ROM Mode 1, used for storing data with error- correction (called ECC, for Error Correction Code) in order to avoid losing data due to degradation of the disc.  CD-ROM Mode 2, used for storing compressed graphical, video, and audio data. To be able to read this type of CD- ROM, a drive must be Mode 2 compatibe

©S.Maciulevičius CD standards  Four more standards:  Green book: Physical specifications for a CD-I (CD Interactive, by Philips)  Orange book: Physical format for writable CDs. It is divided into three sections:  Part I: The CD-MO format (magneto-optical disks)  Part II: The CD-WO format (Write Once, now called CD-R)  Part III: The CD-RW format (CD Rewritable)  White book: Physical format for video CDS (VCD)  Blue book: Physical format for "Extra" CDs (CD-X

©S.Maciulevičius CD-ROM format  A CD-ROM sector contains 2352 bytes, divided into byte frames Layout Type← 2,352 bytes block → CD Digital Audio:2352 bytes of Digital Audio CD-ROM (MODE1): bytes of user data48276 CD-ROM (MODE2): bytes of user data Sync Sector ID Error detection blank/null Error detection

©S.Maciulevičius Data Transfer Speeds  CD-ROM drives are rated with a speed factor relative to music CDs (1x or 1-speed which gives a data transfer rate of 150 KiB per second). 12x drives were common in April 1997  Above 12x speed, there are problems with vibration and heat  Constant angular velocity (CAV) drives give speeds up to 20x but due to the nature of CAV the actual throughput increase over 12x is less than 20/12

©S.Maciulevičius Data Transfer Speeds Transfer Speed KiB/sMbit/s 1x x x x x x x x Transfer Speed KiB/sMbit/s 36x x x x x x x

©S.Maciulevičius CD capacity TypeSectorsData max sizeAudio max sizeTime (MB)(MiB) (approx)(MB)(min) 8 cm94, , MB333, MB360, MB405, MB445, , Note: 90 and 99 minute discs are not standard

©S.Maciulevičius CD-ROM and DVD The DVD (Digital Versatile Disc) is an "alternative" to the CD with six times as much storage space (for the lowest-capacity kind of DVD — single-layer, single-sided

©S.Maciulevičius DVD  The DVD format was originally supported by a consortium of ten multimedia companies  DVD was originally used as an initialism for the unofficial term digital videodisk. It was reported in 1995, at the time of the specification finalization, that the letters officially stood for Digital Versatile Disc (due to nonvideo applications)  The main reason to use DVDs is their storage capacity, which makes them an excellent medium for video. A 4.7 GB DVD can store more than two hours of compressed video in MPEG-2, a format used for compressing images while still keeping them high-quality

©S.Maciulevičius DVD  A DVD can easily be confused with a CD, as both are plastic discs 12 cm in diameter and 1.2 mm thick, which are read using a laser beam  However, CDs use an infrared laser with a wavelength of 780 nanometres (nm), while DVD burners use a red laser with a wavelength of 635 nm or 650 nm  What's more, CD players generally use a lens with a focus of 0.5, while the lenses of DVD players have a focus of 0.6  For this reason, DVDs have grooves whose minimum height is 0.4µ with a pitch of 0.74µ, as opposed to 0.834µ and 1.6µ for a CD

©S.Maciulevičius DVD DVD can be of foowing types:  DVD-ROM (read-only, recorded during fabrication)  DVD-R/RW (DVDs in DVD-R format can only be recorded once, while DVD-RWs can be rewritten up to about 1000 times )  DVD+R/RW (supported by Sony and Philips within the DVD+RW Alliance)  DVD-RAM (This format is mainly used in Japan)

©S.Maciulevičius DVD speeds  DVD drive speeds are measured with a multiplier. For example, 1x DVD transfers data at about 1.3 MB/Sec  A 4x drive could transfer data at four times that speed or about 5.2 MB/Sec. Compare this to the 0.15 MB/sec data transfer for a 1x CD-RW and you’ll see DVD drives are much faster. Almost ten times faster  All DVD videos play at 1x speed  Writing speeds for DVD were 1×, that is, 1350 kB/s, in the first drives and media models. More recent models, at 18× or 20×, have 18 or 20 times that speed

©S.Maciulevičius DVD types TypeCharacteristics Storage capacity Equiv. in music (h.:min.) Equiv. in number of CDs CD 650 MB1:141 DVD-5 single-sided, single layer 4.7 GB9:307 DVD-9 single-sided, dual layer 8.5 GB17:3013 DVD-10 double-sided, single layer 9.4 GB19:0014 DVD-17 double-sided, dual layer 18 GB35:0026

©S.Maciulevičius DVD types Single-sided (DVD-5) Double-sided (DVD-10)

©S.Maciulevičius DVD types Single-sided dual layer (DVD-9) Single-sided dual layer (DVD-18) DVD-5

©S.Maciulevičius New DVD types Traditional DVDs are already exhaust its possibilities Looking for opportunities to increase the capacity of DVD discs that they fit the higher resolution videos, two new technologies were created:  HD DVD (High Definition DVD) – modification of traditional DVDs, when the data are at the same level, as well as in DVDs, but the blue laser is used to ensure a higher recording density: 15 GB / layer instead of 4.7 GB  Blu-ray DVD (BD) – fairly thin protective layer (0.1 mm instead of 0.6 mm), so recording layer is closer to the surface layer, wich less diffuses laser beam; this enables to reduce the size of pits and to rise layer capacity GB, 25 GB or 27 GB

©S.Maciulevičius HD DVD HD-DVD has been supported on the hardware side by NEC, Sanyo, Samsung, Thomson (both also supported Blu-ray), and Toshiba On the software side, HD-DVD has been supported by BCI, Dreamworks, Paramount Pictures, Studio Canal, and Universal Pictures, and Warner (only until May at which time it will be Blu-ray exclusive). Microsoft had also lent its support to HD-DVD, but no longer, as Toshiba has ended HD-DVD support HD-DVD is now officially discontinued (one of reasons - lower capacity comparing to Bue-ray)

©S.Maciulevičius Blue-ray DVD  Blu-ray Disc was developed by the Blu-ray Disc Association, a group representing makers of consumer electronics, computer hardware, and motion pictures  While a standard DVD uses a 650 nanometer red laser, Blu-ray uses a shorter wavelength, a 405 nm blue-violet laser, and allows for almost six times more data storage than a DVD  The Blu-ray Disc physical specifications were completed in 2004  The first mass-market Blu-ray Disc rewritable drive for the PC was the BWU-100A, released by Sony on July 18, It recorded both single- and dual-layer discs and had a suggested retail price of US $699

©S.Maciulevičius Compare CD, DVD and Blue-ray

©S.Maciulevičius Blue-ray DVD General Specifications:  Storage Capacity - Pre-recorded Playback Material (BD-ROM): Single-layer (25GB) - Dual-layer (50GB)  Storage Capacity: Home Recording (BD-R/BD-RE): Single-layer (25GB) - Dual-layer (50GB)  Data Transfer Rate: 36 to 48 MBPS (Megabits per Second) average - capable of up to 54 MPS  Network Capability: Although the Blu-ray format supports networking and internet capabilities, built-in networking and Ethernet ports on individual Blu-ray Disc Players is optional

©S.Maciulevičius Blue-ray DVD Drive speed Data rateWrite time for Blu-ray Disc (minutes) Mbit/sMB/sSingle-LayerDual-Layer 1× × × × ×

©S.Maciulevičius Comparative parameters ParameterCDDVDBlu-rayHD-DVD Singe- or doube-sided11 or 2 Layers11 or 2 Capacity (GB)0,684,7/9,425/5015/30 Protective layer (mm)1,200,600,100,60 Distance betw. tracks (μm)1,600,740,320,40 Minimal length of pit (μm)0,830,410,1490,204 Laser wavelength (nm) Linear speed (m/s)1,303,497,365,60 Transfer speed, Mb/sN/D11,15436

©S.Maciulevičius Improving Blue-ray DVD  Although the Blu-ray Disc specification has been finalized, engineers continue to work on advancing the technology  Quad-layer (100 GB) discs have been demonstrated on a drive with modified optics (TDK version) and standard unaltered optics ("Hitachi used a standard drive")  Hitachi stated that such a disc could be used to store 7 hours of 32 Mbit/s video (HDTV) or 3.5 hours of 64 Mbit/s video (Cinema 4K)  In 2006, TDK announced that they have created a working experimental Blu-ray Disc capable of holding 200 GB of data on a single side, using six 33 GB data layers

©S.Maciulevičius Improving Blue-ray DVD  In December 2008, Pioneer Corporation unveiled a 400 GB Blu-ray Disc (containing 16 data layers, 25 GB each) that will be compatible with current players after a firmware update  Its planned launch is in the 2009–10 time frame for ROM and 2010–13 for rewritable discs  Ongoing development is under way to create a 1 TB Blu- ray Disc as soon as 2013  The Mini Blu-ray Disc (also, Mini-BD and Mini Blu-ray) is a compact 8 cm-diameter variant of the Blu-ray Disc that can store approximately 7.5 GB of data

©S.Maciulevičius Holographic Versatile Disc  The Holographic Versatile Disc (HVD) is an optical disc technology that, in the future, may hold up to 6TB of information, although the current maximum is 500GB  It employs a technique known as collinear holography, whereby two green laser beams are collimated in a single beam  The structure of the disc places a thick recording layer between two substrates and incorporates a dichroic mirror that reflects the blue-green light carrying the holography data but allows the red light to pass through in order to gather servo information

©S.Maciulevičius Holographic Versatile Disc

©S.Maciulevičius HVD vs DVD Blu-rayHD-DVDHVD Initial cost for recordable disc ~ $18~ $10~ $120 Initial cost for recorder/player ~ $2,000 ~ $3,000 Initial storage capacity54 GB30 GB300 GB Read/write speed36.5 Mbps 1 Gbps

©S.Maciulevičius AO-DVD  Iomega Corporation got two highly notable patents for its work with nano-technology and optical data storage, and external storage media  New technologies could potentially allow times more data to be stored on a DVD with data transfer rates 5-30 times faster than today's DVDs, and at similarly low costs  An articulated optical-digital versatile disc (AO-DVD) potentially can store up to 850GB. This is 200x the amount that can be fitted onto a single layer DVD. Data rates are good too claiming to be nearly 30 times faster than today’s DVDs