CD TechnologySystems Management

Spring 2010

Objectives

Explain how data isStoredRetrieved

Explain the differences betweenCD-ROMCD-RCD-RWDVD-RW

Objectives

Describe how discs are constructedDescribe major parts of the disc driveExplain how to install a new driveDiscuss compatibility

Optical: Background

First use of optical data storage was used around 5,000 years ago with the Egyptians.

Optical: Background

First modern use of optical data storage photography about 200 years ago.Optical recording was in the past and is

currently viewed as the replacement to magnetic recording.

Optical: AdvantagesLight can be easily used to record digital

information since the invention of the laser.Optical recording systems are more

reliable than magnetic recording systems.Optical recording systems can be

transferable and more easily removed than magnetic recording systems.

Optical: DisadvantagesSlower random data accessWhy?

Limited application for data storageLife and stableness of the laserWhat might be the reason(s)?

Mechanical damage because of vibration

Optical Storage Consists of an injection-molded piece of

clear polycarbonate plastic. A thin, reflective aluminum layer is

sputtered onto the disc, covering the bumps.

Then an acrylic layer is sprayed over the aluminum to protect it.

The label is then printed onto the acrylic.

Optical Disc

Data physically embedded into disc surfaceCombines constant

linear velocity (CLV) and constant angular velocity (CAV) to read the data

Optical: How It Works

Most optical drives work in very similar ways. They detect variations and patterns

in the optical properties on the media surface.Variations can be pits and lands or

matte and reflective dye on the disc

Optical: How It Works

CD/DVD – Detect patterns & variations in light sensitivity.

MO Drives – detect changes in light polarization (more popular in Japan)

Optical Eye

Optical Storage

A single spiral track of data, circling from the inside of the disc to the outsideThe fact that the spiral track starts at the

center means that the disc can be smaller than 4.8 inches (12 cm) if desired.

Optical Storage

CD ROM (650 MB) written by a manufacturer and read only memory.

CD-R (650 MB) written only once by a consumer, making these disks recordable. Now available software/hardware allows for multi-session burns

CD-RW (650 MB) written to and erased from 1 to approximately 25 times, making

these disks rewritable. DVD (4.7 to 17 GB)

much higher storage capacity than a CD and a different storing process.

BD / Blu-ray (25 GB to 50 GB) next-generation optical disc format, developed to enable

recording, rewriting and playback of high-definition video (HD), as well as storing large amounts of data.

Optical Storage – CD-R / CD-RW

CR-RUses an organic dye that is photosensitive

reflective dye, that when heated turns darkOnce “burned” cannot be changed

CD-RWUses “phase change”Heated to one temperature becomes reflectiveHeated to a higher temperature becomes dull

Optical Storage – DVD

Similar to CDs but with six times more storage capacity

DVDs are preferred for movies and Software

CDs are still the preferred in publishing music albums because of cost

DVD players can play both CDs and DVDs while CD players can only play CDs.

Optical Storage – Blu-ray Disc (BD)

Next-generation optical disc formatFormat developed to Enable recording, rewriting and playback of

high-definition video (HD)Store large amounts of data

Offers more than five times the storage capacity of traditional DVDsCan hold up to 25GB on a single-layer disc Can hold up to 50GB on a dual-layer disc

Optical Storage

Standards

Rainbow Books publish the standardsRed – CD AudioYellow – File FormatsOrange – MultisessionWhite, Blue, Beige, Green, Purple, Scarlet,

BlackThere are no “colored-books” for DVD or

Blu-ray Discs

CD Drive

Inside CD Drive

Tray motor Ejects and pulls in CD tray

Read head Shines light on CD and

reads reflection Spin motor Spins the CD at various

speeds

Typical Components

Reading Data From a CD Laser shines light on disk Pits and lands reflect light

differently Reflected light is picked up

by sensor Sensor changes light to

electrical signal for the computer

Motor moves the head to read all parts of the spinning CD.

CD Transfer Rate

1X drive transfers at 150 KBpsTheoretically take “X” multiplied by

150 KBps to calculate transfer rate72X CD drive has a designated transfer

rate of 10.8 MBps

CD File Format Standards

High SierraOriginal standard set in 1985 Used primarily in the US (uncommon now)

ISO 9660Replaced High Sierra as the world standard

Universal Disk Format (UDF)Found on most authored optical disks including

DVDs (it is the DVD adopted standard)Allows the disk to be “bootable”

Pits and Lands

Reading is a matter of bouncing a low-powered laser beam off the reflective layer in the disc.

The laser shines a focused beam on the underside of the disc, and a photosensitive receptor detects when the light is reflected back.

When the light hits a land (flat spot) on the track, the light is reflected back, however when the light hits a pit (hole), no light is reflected back.

CD ROM Surface

Surface laid out as one continuous spiral of sectors of equal length that hold equal amounts of data

Track and Sectors

The pits are stamped into a single spiral track with a spacing of 1.6 microns between turns, corresponding to a track density of 625 turns per millimeter or 15,875 turns per inch. This equates to a total of 22,188 turns for a normal 74-minute (650MiB) disc.

A comparison of a CD's pit size and track spacing vs. that of a DVD

CD Compared to DVD

Installing Optical Drive

Most CD drives use PATA or SATA connections and support the ATAPI standard. ATAPI treats a CD-media drive exactly as

though it were an ATA drive. PATA CD drives have regular 40-pin IDE

connectors and master/slave jumpersSATA CD drives use standard SATA cableYou install them the same way you install

any ATA HD

Installing a CD-ROM Drive

Installing a DVD Drive

Device Manager

Auto Insert Notification

Enables Windows to automatically detect the presence of a CD

Windows 2000/XP: is called Autoplay

For Music CDs: track 1 plays automatically

For Data CDs: windows search for a text file: autorun.inf

Autorun can be disabled When you insert a CD or DVD

media disc with no autorun.inf, XP asks you what you want to do.

Applications

A regular CD-ROM drive installation involves no applications. Install it, and Windows should see it.

CD-R and CD-RW drives require applications to enable their burning feature (writing process)

DVD-media drives need SW to enable you to watch movies, burn DVDs, …

Examples of CD-burning programs: Nero Burning ROM Roxio’s Easy Media Creator

Troubleshooting CD/DVD drives

Check orientation of data cable Check power connector Jumper settings Recognized in BIOS Stuck disk Clean the drive Use damp cloth to clean disksWipe from center outwards Handle by edges only, don’t touch surface