How data is written on and read from optical disk

1. How data is written on and read from optical disk Aaron Ellard

2. What is an optical disk? A storage medium from which data is read and to which it is written by lasers. Optical disks can store much more data -- up to 700 times more-- than most portable magnetic media, such as floppies. There are several types of optical disks:

3. CD-ROM Like audio CDs, CD-ROMs come with data already encoded onto them. The data is permanent and can be read any number of times, but CD-ROMs cannot be modified.

4. WORM Stands for write-once, read -many. With a WORM disk drive, you can write data onto a WORM disk, but only once. After that, the WORM disk behaves just like a CD-ROM

5. erasable • Optical disks that can be erased and loaded with new data, just like magnetic disks. These are often referred to as EO (erasable optical) disks.

6. How is an Optical Disk Read? The data is read through lasers CD-ROM,WORM, erasable, and so on are read with a red laser where the disk driver deciphers the information.

7. BLU-RAY ® Blu-ray Disc (BD) is an optical disc storage medium designed to surpass the DVD format. The biggest difference is it is read using a blue laser which uses shorter wave lengths to read the data .

8. Questions • What does WORM stand for? • write-once, read –many • What color is the laser that reads BLU-RAY®? • Blue • What color laser reads other disc? • Red • Roughly how much more data can a standard CD-Rom have than a standard floppy • About 700 times more