13-08-2012, 01:08 PM
CD-ROM and CD Writer Drives
CD-ROM and CD Writer Drives.ppt (Size: 186 KB / Downloads: 34)
Features of Compact Disc
Removable storage media
Cheap and reliable media
Round disc with a hole in center
Stores more data than the floppy disk
Basic layers are:
polycarbonate plastic - Hard transparent plastic layer of the disc
aluminum - Reflects the laser beam from the CD drive like a mirror that reflects light
acrylic – plastic resembles like glass protects the CD layers
label - Enables you to name the CD for identification
Audio CD
Used to store music
Song quality does not decrease, because there is no friction between the CD player and the Audio CD.
Songs recorded on audio CD have a better quality
Longer shelf life
Stores about 74 minutes of music
CD-R
Data once written cannot be erased
Useful to backup data
Used to create music CDs which can be played on music systems
Has a special layer between polycarbonate plastic layer and reflective aluminum layer and made up of photosynthetic
CD-RW
Enables to rewrite data to CD-RW disc
Data can be erased from CD-RW disc
Useful when storing files that require update regularly
Use a special phase change compound layer that makes it possible to rewrite data
CD-ROM Drive
Read data from CD-ROM disc and Audio CD
Used to install software and play music from a Audio CD
Speed is specified using numbers followed by X (X=150 KBps)
CD-R Drive
Useful for backing up data that must not be modified
Can write using a single or multiple sessions
Speed of the CD-R drive is specified using two numbers
Components of the CD Drive – II
Optical Head
Consists of a read laser and optical sensor
Delicate and expensive part
High precision part
CD writer has two lasers for reading and writing data and the strength of write laser is very strong
Head Actuator
Moves optical head forward and backward by the help of a stepper motor
Enables to access all parts of the CD
Spindle Motor
Catches and spins CD when inserted in CD drive
Reduces the spinning speed as the head actuator moves from the center outward
Connectors
Connect CD drive to system motherboard
Located at the back of the CD drive
CD Drive uses the 40 pin connector