Mass Storage Optical Systems Dr M Tanvir Afzal

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Mass Storage Optical Systems Dr. M. Tanvir Afzal

Mass Storage Optical Systems Dr. M. Tanvir Afzal

Mass Storage Examples ü Compact Disk (CDs) ü Digital Versatile Disks (DVDs) ü Blu-ray

Mass Storage Examples ü Compact Disk (CDs) ü Digital Versatile Disks (DVDs) ü Blu-ray Disks (BDs) 2 Dr. M. Tanvir Afzal

Compact Disk ü 12 centimeter in diameter ü Consists of reflective material https: //en.

Compact Disk ü 12 centimeter in diameter ü Consists of reflective material https: //en. wikipedia. org/wiki/Compact_disc 3 Dr. M. Tanvir Afzal

Data Storage on CD ü Information is recorded on them by creating variations in

Data Storage on CD ü Information is recorded on them by creating variations in their reflective surfaces. ü Data is stored on a single track spiral from inside-outside. ü Each track is divided into sectors, ü capacity of a sector is 2 KB of data, 1/75 of a second audio music. 4 Dr. M. Tanvir Afzal

CD 5 Dr. M. Tanvir Afzal

CD 5 Dr. M. Tanvir Afzal

Data Retrieval on CD ü Retrieval using a Laser that detects the irregularities on

Data Retrieval on CD ü Retrieval using a Laser that detects the irregularities on the reflective surface of the CD as it spins 6 Dr. M. Tanvir Afzal

CD Technology ü Initially applied on audio recording using format CD-DA (compact disk-digital audio)

CD Technology ü Initially applied on audio recording using format CD-DA (compact disk-digital audio) ü Format is being used even today to store computer data ü Single Track 7 Dr. M. Tanvir Afzal

Random Retrieval As all sectors are not individually accessible in Optical system having one

Random Retrieval As all sectors are not individually accessible in Optical system having one track, therefore, the data retrieval is faster in magnetic systems than optical systems. Optical System is best suited for long continuous string of data. 8 Dr. M. Tanvir Afzal

DVDs (Digital Versatile Disks) CDs capacity is 600 to 700 MB, however, DVD has

DVDs (Digital Versatile Disks) CDs capacity is 600 to 700 MB, however, DVD has space in GBs as have multiple semitransparent layers, which can be viewed by precise focused laser. 9 Dr. M. Tanvir Afzal

BDs (Blue Ray Disks) BDs use a blue-violet spectrum of light (instead of red),

BDs (Blue Ray Disks) BDs use a blue-violet spectrum of light (instead of red), which is able to focus its laser beam with very fine precision. BDs provide five time capacity than DVDs. 10 Dr. M. Tanvir Afzal

Summary Optical System ü CD, DVD, BDs, ü Data Storage and Retrieval ü Continuous

Summary Optical System ü CD, DVD, BDs, ü Data Storage and Retrieval ü Continuous access over random access 11 Dr. M. Tanvir Afzal