Optical Storage Devices
Optical Storage Devices
• An optical disk is a high-capacity storage medium.
An optical drive uses reflected light to read data.
• To store data, the disk's metal surface is covered with tiny dents (pits) and flat spots (lands), which cause light to be reflected differently.
• When an optical drive shines light into a pit, the light cannot be reflected back. This represents a bit value of 0 (off). A land reflects light back to its source,
Representing a bit value of 1 (on)
CD-ROM
• In PCs, the most commonly used
Optical storage technology is called
Compact Disk Read-Only Memory (CD-ROM).
• A standard CD-ROM disk can store up to 650
MB of data, or about 70 minutes of audio.
• Once data is written to a standard CD-ROM which causes light to be reflected differently.
Disk, the data cannot be altered or overwritten.
Optical Storage Devices - DVD-ROM
• A variation of CD-ROM is called Digital Video Disk
Read-Only Memory (DVD-ROM), and is being used in place of CD-ROM in many newer PCs.
• Standard DVD disks store up to 9.4 GB of data— enough to store an entire movie. Dual-layer DVD disks can store up to 17 GB.
• DVD disks can store so much data because both sides of the disk are used, along with sophisticated data compression technologies.
CD-Recordable (CD-R)
This drive lets you record your own CDs, but data cannot be overwritten once it is recorded to the disk.
CD-Rewritable (CD-RW)
This drive lets you record a
CD, then write new data over the already recorded data. Photo CD
This technology is used to store digital
• An optical disk is a high-capacity storage medium.
An optical drive uses reflected light to read data.
• To store data, the disk's metal surface is covered with tiny dents (pits) and flat spots (lands), which cause light to be reflected differently.
• When an optical drive shines light into a pit, the light cannot be reflected back. This represents a bit value of 0 (off). A land reflects light back to its source,
Representing a bit value of 1 (on)
CD-ROM
• In PCs, the most commonly used
Optical storage technology is called
Compact Disk Read-Only Memory (CD-ROM).
• A standard CD-ROM disk can store up to 650
MB of data, or about 70 minutes of audio.
• Once data is written to a standard CD-ROM which causes light to be reflected differently.
Disk, the data cannot be altered or overwritten.
Optical Storage Devices - DVD-ROM
• A variation of CD-ROM is called Digital Video Disk
Read-Only Memory (DVD-ROM), and is being used in place of CD-ROM in many newer PCs.
• Standard DVD disks store up to 9.4 GB of data— enough to store an entire movie. Dual-layer DVD disks can store up to 17 GB.
• DVD disks can store so much data because both sides of the disk are used, along with sophisticated data compression technologies.
CD-Recordable (CD-R)
This drive lets you record your own CDs, but data cannot be overwritten once it is recorded to the disk.
CD-Rewritable (CD-RW)
This drive lets you record a
CD, then write new data over the already recorded data. Photo CD
This technology is used to store digital