1. Introduction 2. Methods for I/O Operations 3. Buses 4. Liquid Crystal Displays 5. Other Types of...

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Contents of the Lecture

1. Introduction2. Methods for I/O Operations3. Buses4. Liquid Crystal Displays5. Other Types of Displays6. Graphics Adapters7. Optical Discs

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2Input/Output Systems and Peripheral Devices (07-1)

7. Optical Discs

Classification of Optical DiscsCompact Disc Physical MediumData Organization and EncodingCD-ROM DriveCompact Disc TypesDVDBlu-ray Discs

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Classification of Optical Discs (1)

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Optical discs:R/O (Read/Only): recorded by manufacturerR/W (Read/Write): recorded by the user

Video discs: CAV (Constant Angular Velocity)CLV (Constant Linear Velocity)

Compact discs:CD-DA (Compact Disc-Digital Audio)CD-3

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CD+G (CD+Graphics) CD+MIDI (CD+Musical Instruments Digital Interface)CD I Ready‑ (CD‑Interactive Ready)CD EXTRA: multi-session mixed disc; it contains an audio part and a data partCD TEXT: extension of the CD-DA format for recording the texts of songsCD-I (CD-Interactive): it may contain video images, graphics, animation, sound, text, data

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CD ROM XA‑ (CD ROM ‑ Extended Architecture): extension of the CD-ROM format with characteristics defined for the CD-I format Photo CD: implementation of the CD-ROM/XA format for storing photographsVideo CD: format for recording compressed video and audio dataSVCD (Super Video CD): improved video and audio quality compared to Video CD formatSACD (Super Audio CD)

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DVD (Digital Versatile Disc)BD (Blu-ray Disc)

BD-ROM AV (BD-ROM Audio Visual)Writeable discs:

CD R‑ (CD‑Recordable) DVD R‑ (DVD-Recordable)DVD+R (DVD+Recordable)BD-R (BD-Recordable)BD-R AV (BD-Recordable Audio Visual)

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Rewriteable discs:CD MO‑ (CD‑Magneto Optical)CD RW‑ (CD-Read/Write)DVD-RW (DVD-Read/Write)DVD+RW (DVD+Read/Write)DVD-RAMBD-RE (BD-Rewritable)BD-RE AV (BD-Rewritable Audio Visual)

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7. Optical Discs


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Input/Output Systems and Peripheral Devices (07-1) 10

Compact Disc Physical Medium (1)

Diameter: 12 cm; thickness: ~1.2 mmData are recorded as cavities called pits placed between surfaces called lands Different reflection degree for pits and lands

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Compact Disc Physical Medium (2)

Data are recorded on a single spiral Distance between two consecutive tracks: 1.6 m Each bit of information requires ~300 nm

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7. Optical Discs


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Data Organization and Encoding

Data Organization and EncodingData Organization Levels Data Recording and EncodingFirst Level of Error CorrectionSector Format Second Level of Error CorrectionSub-Channels

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Data Organization Levels

At the lowest level, data are recorded as pits and lands

Data are encoded high recording density; reliable error recovery

At the next level, data are organized into sectors and tracks The High Sierra specifications (ISO 9660 standard) define a file system

Extensions: Rock Ridge, HFS, Joliet

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Data Recording and Encoding (1)

The bits are recorded on the medium using the RLL (Run Length Limited) method

Each pit land transition: bit of 1No transition: bit of 0

Encoding by which a data byte is represented through 14 channel bits Eight-to-Fourteen Modulation (EFM)

3 merging bits are inserted Data are broken up into blocks called frames

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Data Recording and Encoding (2)

Frame structure:Synchronization header Control byte 2 12 data bytes 2 4 bytes for error detection and correction (CIRC - Cross Interleaved Reed Solomon ‑Code)

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Synchronization Control Data (L) CIRC Data (R) CIRC

27 bits 1 byte 12 bytes 4 bytes 12 bytes 4 bytes




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First Level of Error Correction

The error detection and correction system used within the frames: CIRC (Cross Interleaved Reed Solomon Code‑ )

Integrated at hardware level into the disc drives

Two components:The “Cross interleave” component breaks up the long errors into several short errors The “Reed Solomon‑ ” component provides the error correction

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Sector Format (1)

Sector = 98 frames98 control bytes24 98 = 2352 data bytes 8 98 = 784 error detection and correction bytes

Format similar to that of audio discs For direct access to each sector, synchronization bytes and a header containing the sector address are used

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Sector Format (2)

12 synchronization bytes 00 FF .. FF 00

The header contains 4 fields (x1 byte)M field of absolute address (Minute), 0..99S field of absolute address (Second), 00..59F field of absolute address (Frame), 00..74Data mode field

Two modes of organization: Mode 1, Mode 2

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Sector Format (3)

Mode 1Provided for data tracks (programs)2048 bytes of data The Error Detection Code (EDC) The Error Correction Code (ECC)

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Synchronization Header Data EDC 0 ECC

12 bytes 4 bytes 2048 bytes 4 bytes 8 bytes 276 bytes


Sector Format (4)

Mode 2Provided for audio and video applications The EDC, ECC fields contain dataA sector contains 2048+288 = 2336 bytes

Mixed mode discs (ISO/IEC 10149)First track: data (mode 1) Other tracks: audio/video information (mode 2)

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Synchronization Header Data12 bytes 4 bytes 2336 bytes




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Second Level of Error CorrectionThe error rate ensured by the CIRC method: 10-9 insufficient for data discs For data discs a second level of error detection and correction is provided

4 bytes for error detection (EDC)276 bytes for error correction (ECC)

L EC‑ (Layered Error Correction), rate of 10-12 The error detection code: Cyclic Redundancy Check (CRC)The error correction code: Reed-Solomon

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Sub-Channels

Each bit of a control byte is identified by a letter: P, Q, R, S, T, U, V , WBits that are assigned the same letter make a sub-channel

The bits that occupy the first position in all the 98 control bytes make sub-channel PThe bits in the second position: sub-channel Q

Sub-channel Q in the lead-in area keeps the table of contents (TOC)

The last 6 bits: sub-channel R W‑



7. Optical Discs


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CD-ROM Drive (1)

The laser diode emits an infrared beam The beam is focused on the disc surfaceThe beam is positioned with a servomechanismPart of the beam is reflected back and directed to a photodiode → electric signal

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CD-ROM Drive (2)

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CD-ROM Drive (3)

Positioning mechanismMoves the mirror and the lens system The optical assembly moves on a set of rails The precise positioning onto a track is achieved with a microcontroller and an electronic servo system The servo system measures the signal level and adjusts the position of the read assembly

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CD-ROM Drive (4)

Common systems use three beams:The beam generated by the laser diode is split into three beams with a polarized prismThe intensity of the side beams is measured signal for correcting the beam position

Compensating vertical movement:The photodiode is split into 4 quadrants On the disc’s deviation, the spot becomes elliptical the signals generated by the quadrants will differ The objective lens is moved accordingly

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CD-ROM Drive (5)

Rated speed (“X” speed)Refers to the spin speed of the disc It is an indicator of the maximum theoretical transfer rate A single-speed (1X) drive has the same spin speed as a standard audio CD drive

Audio drive: 75 sectors/s 75 2336 = 175,200 B/s = 171.09 KB/s1X CD-ROM drive: 75 2048 = 153,600 B/s = 150 KB/s

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CD-ROM Drive (6)

CLV (Constant Linear Velocity) The spin speed is variable: higher towards the disc centre The transfer rate is constant Method used for audio CD drives and early generations of CD-ROM drives (1X..12X)

The first audio CD drives were designed to transfer the same amount of data in each second

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CD-ROM Drive (7)

CAV (Constant Angular Velocity) The spin speed is constant The transfer rate is variable Advantage: there is no need to change the spin speed Disadvantage: the transfer rate is reduced towards the center of the disc Method used for CD-ROM drives with a spin speed of over 12X

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CD-ROM Drive (8)

TrueX technologyAllows to increase the performance of CD-ROM drives Several laser beams are used to scan simultaneously multiple tracks ASIC that contains: signal processor, servo controller, decoder, error correction system, ATAPI interface External chip: SCSI, USB, or IEEE 1394 interface

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CD-ROM Drive (9)

The laser beam is split with a diffraction gratingThe beams pass through the unidirectional mirrorFocusing: attained with the central beam Higher transfer rates at lower revolution speeds reducing vibrations

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7. Optical Discs


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Compact Disc Types

Compact Disc Types CD-DACD-DA VariantsSACDCD-RCD-RW

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CD-DA (1)

CD-DA (Compact Disc Digital Audio)

Early generation discs had a duration of 60 minutes Later discs: 74 or 80 minutesThe standard: “Red Book” documentMost of the later standards are based on the “Red Book” specifications with regard to the media and read procedure

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CD-DA (2)

The audio signal (analog) is sampled Sampling rate: 44.1 KHz The Pulse Code Modulation (PCM) is used

The amplitude is represented on 16 bits Stereo recording Each second of sound requires 44,100 2 2 = 176,400 data bytes

The capacity of an 80-minute disc: 176,400 60 80 807 MB

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CD-DA (3)

Audio CD discs are not always produced in a complete digital way Processing phases: recording, editing/ mixing, dubbing The type of processing phases: indicated through a three-letter code

DDD: completely digital discADD: analog recordingAAD: analog recording and editing

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Compact Disc Types


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CD-DA Variants (1)

CD-3Diameter: 3 inches (~8 cm)Capacity: 20 minutes (CD Single)

CD+G (CD Plus Graphics) Uses the R W sub-channel‑ to store the texts of songs or some graphical data These can be displayed with a TV set or a CD-interactive (CD-I) drive

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CD-DA Variants (2)CD+MIDI

Uses the R W sub-channel to make special ‑effects synchronized with the music MIDI controls: note, instrument

CD-I ReadyThe interval between index 0 and 1 is increased form 2 seconds to 3 minutesCan be used to record: text of the songs, information about the artist, images Reading this information: with a CD-I drive

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Compact Disc Types


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SACD (1)

SACD – Super Audio Compact Disc Uses a recording technology developed by Philips and Sony (2000)The disc contains two layers:

A reflective layer (audio CD): stereo, 44.1 KHz, 16 bits/sample A high-density semitransparent layer (DVD): stereo CD-DA recording + 6-channel recording + data

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SACD (2)

The two layers are read with two laser beams, with different wavelengths:

Reflective layer: = 780 nmSemitransparent layer: = 650 nm

Capacity of the high-density semitransparent layer: 4.38 GB Recording technology: Direct Stream Digital (DSD)

Sampling rate: 64 x 44.1 KHz = 2822.4 KHz; 1 bit/sample

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SACD (3)

Pulse Density Modulation (PDM)The signal amplitude is determined by the relative density of the pulses (values of 1)

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SACD (4)

Bit rate per channel: 2,822,400 bits/s (4 times higher compared to CD-DA)Frequency response: 0..100 KHz (compared to 5 Hz..20 KHz for CD-DA)Dynamic range (ratio between the highest and lowest sound intensity): 120 dB (compared to 96 dB for CD-DA)The sound quality is also improved when the disc is played back with regular CD players

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SACD (5)

The CD-DA (PCM) recording is obtained from a DSD recording via the Super Bit Mapping Direct conversion technology

A FIR digital filter with 32,639 taps is usedThe quality is comparable with that of 20-bit or 24-bit recordings

The stereo recording and the 6-channel recording on the high-density layer use the DSD technology

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SACD (6)

A lossless compression method is used Direct Stream Transfer

The bit rate is reduced with ~50%Copy protection:

A watermark (text or graphics) is written to the reflective side of the disc Invisible information is also written to disc

Advantages of SACD disc:High quality allows archiving Compatibility with existing CD players

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Compact Disc Types


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CD-R (1)

CD-R (CD Recordable) CD WORM‑ (CD Write Once, Read Many) CD WO‑ (CD Write Once)

Specifications defined in the “Orange Book” document, Part II (1990)CD-ROM discs are based on the CD audio standard, changing the interpretation of dataCD R‑ discs define new physical media and recording methods, using the standard formats

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CD-R (2)

Writing method: changing the reflectivity of an organic dye Photosensitive organic dyes:

Cyanine (blue cyan)Phthalocyanine (greenish blue) Azo (dark blue)

To protect against oxidation, a metal layer (silver alloy or gold) is coated over the dye

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CD-R (3)

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CD-R (4)

Writing: with a laser beam that heats up selectively certain areas

In the heated areas, the organic dye changes its chemical composition “Burned” areas reflect light to a lesser degree correspond to pits“Non-burned” areas reflect light to a higher degree correspond to lands

The disc can be read by regular drives

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CD-R (5)The disc is stamped with a spiral pre-groove

It is similar to the spiral on a regular CD The groove is used by the CD R‑ drive during recording to follow the data path on the disc

If the disc were completely unformatted, writing the spiral tracks would be complex

The groove has a sinusoidal excursion (deviation) of 0.3 μm at a frequency of 22.05 KHz

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CD-R (6)

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CD-R (7)

CD R‑ discs have two additional data areas located before the lead-in area

Are used to store data specific to the recording process

Program Memory Area (PMA)Contains the track numbers of the recorded titles as well as their start and stop addresses

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CD-R (8)

Power Calibration Area (PCA)Used to calibrate the laser power trial recording The optimal power depends on: recording speed, ambient temperature, humidity, disc typeA maximum of 99 calibrations are allowed for a disc

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CD-R (9)

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Compact Disc Types


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CD-RW (1)

CD RW‑ (CD ReWritable) CD E‑ (CD Erasable)

Specifications defined in the “Orange Book” document, Part III (1997)The dye layer is replaced with a special phase-change recording layer

Can change state when a certain energy is applied to it and can return to the initial state

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CD-RW (2)

When the material is heated to a certain temperature and then is cooled, a crystalline structure is formed land When the material is heated to a higher temperature, an amorphous structure is formed pit

Recording layer: alloy of silver, indium, antimony, and tellurium

Placed between two dielectric layers that eliminate excess heat during writing

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CD-RW (3)

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CD-RW (4)

WritingThe recording layer is heated to a temperature above the melting point The crystals get to an amorphous state If the cooling is fast, the amorphous state is maintained

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CD-RW (5)

ErasingThe recording layer is heated below the melting point, but above the crystallization point The temperature is maintained for a time longer than the min. crystallization time

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CD-RW (6)

OverwritingNew pits are created using the laser beam for writing A constant laser beam is used to create new crystalline lands The process can be repeated about 1000 times

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CD-RW (7)

The reflectivity of CD-RW discs is lower than that of regular CDs

Regular CDs: min. 70% for lands, max. 28% for pits CD-RW discs: 15..25% for lands Dual-function drives The MultiRead specifications of OSTA (Optical Storage Technology Association) have been developed to solve the compatibility issues

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Summary (1)

On optical discs, data are recorded as pits and lands

Pits and lands have different reflectivityData are encoded to provide high density and reliable data recovery

For compacts discs, two levels of error correction can be used

At the frame level: used for all compact disc formatsAt the sector level: used for data discs



Summary (2)

Optical drives use a laser beam positioned with a servomechanism

The beam is reflected back and electrical pulses are generated with a photodiode

The first CD format developed was the audio compact disc (CD-DA)

It uses the Pulse Code Modulation (PCM)Various CD-DA formats use the R-W sub-channel to store texts or images

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Summary (3)SACD discs contain two layers: an audio CD layer and a DVD layerWriting of CD-R discs is based on changing the reflectivity of a photosensitive dye

The properties of pits and lands are emulatedCD-RW discs use a phase-change recording layer

Crystalline and amorphous areas can be formed in a reversible mannerDifferent power settings of the laser are used for writing, erasing, and reading

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Concepts, Knowledge (1)

Compact disc data organization levelsCompact disc data recording and encodingLevels of error correctionCompact disc sub-channelsCD-ROM drive structure and operationTrueX technologyCD+G formatCD+MIDI formatSACD format

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Concepts, Knowledge (2)

Direct Stream Digital recording for SACD discsCD-R disc writingSpiral pre-groove of CD-R discsProgram memory area of CD-R discsPower calibration area of CD-R discsPhase-change recording layer of CD-RW discsCD-RW disc writingCD-RW disc erasingCD-RW disc overwriting

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