HOW DO CD'S WORK
CD:
Compact disk.
Record, store and play back audio, video in the form of digital data.
History of CD:
James Russell invented an alternative for phonograph.
First CD released in 1982.
Previously it is read only, later on changed to record on them.
Phonograph:
Mechanical recording and reproducing of sound.
Types of CD:
CD ROM.
Mini CD.
CD-R.
CD+R.
CD-RW.
CD ROM:
Contain music.
Cannot be erased or changed.
Mini CD:
Single song recording.
CD-R:
Recordable.
Record data or music once.
CD+R:
Increase amount of storage.
CD-RW:
Erased and reused.
Disc structure:
CD made from 1.2 millimeters thick.
A. Data encoded by using bumps.
Opposite side of label.
B. Shiny layer reflects laser.
Contains data.
C. A layer of lacquer protects the shiny layer.
D. Artwork is screen printed on top of disc.
E. A laser beam reads the CD and is reflected back to a sensor, which converts into electronic data.
Lacquer:
A liquid made of shellac dissolved in alcohol, that dries to form protective coating.
Shellac:
Lac that has been purified and formed into thin sheets.
Data stored on CD:
Capacity of data storage equivalent to 700 mb.
CD's are played they rotates around and laser beam is used to read the data.
Store data CD is to be burned.
Data stored as pits and lands.
Each change from pit to land and land to pit represent 0 when no change it is 1.
Instead of pits and land we use dye.
For unburned = 1, Absorbed = 0.
Inside CD player on CPU:
Driver motor.
Laser and lens system.
Tracking mechanism.
Driver motor:
Rotates disc between 200 and 500 rpm depends on track is being read.
Laser and lens system:
Reads data.
Tracking mechanism:
Timely ordered sequence of location data.
RPM:
Revolutions per minute.
No of rotations around a fixed axis in one minute.
DVD:
Digital versatile disc.
Can store more data than CD by changing the light to red light.
Why the DVD can store more data by using red light?
Shorter wavelength when compared to infra red in electromagnetic spectrum.
Blu-ray:
More data than DVD.
Changing light to blue.
Advantages:
Cheap.
Reliable.
Fast to access data.
Disadvantages:
Damaged.
Small storage than DVD.
Compact disk.
Record, store and play back audio, video in the form of digital data.
History of CD:
James Russell invented an alternative for phonograph.
First CD released in 1982.
Previously it is read only, later on changed to record on them.
Phonograph:
Mechanical recording and reproducing of sound.
Types of CD:
CD ROM.
Mini CD.
CD-R.
CD+R.
CD-RW.
CD ROM:
Contain music.
Cannot be erased or changed.
Mini CD:
Single song recording.
CD-R:
Recordable.
Record data or music once.
CD+R:
Increase amount of storage.
CD-RW:
Erased and reused.
Disc structure:
CD made from 1.2 millimeters thick.
A. Data encoded by using bumps.
Opposite side of label.
B. Shiny layer reflects laser.
Contains data.
C. A layer of lacquer protects the shiny layer.
D. Artwork is screen printed on top of disc.
E. A laser beam reads the CD and is reflected back to a sensor, which converts into electronic data.
Lacquer:
A liquid made of shellac dissolved in alcohol, that dries to form protective coating.
Shellac:
Lac that has been purified and formed into thin sheets.
Data stored on CD:
Capacity of data storage equivalent to 700 mb.
CD's are played they rotates around and laser beam is used to read the data.
Store data CD is to be burned.
Data stored as pits and lands.
Each change from pit to land and land to pit represent 0 when no change it is 1.
For unburned = 1, Absorbed = 0.
Inside CD player on CPU:
Driver motor.
Laser and lens system.
Tracking mechanism.
Driver motor:
Rotates disc between 200 and 500 rpm depends on track is being read.
Laser and lens system:
Reads data.
Tracking mechanism:
Timely ordered sequence of location data.
RPM:
Revolutions per minute.
No of rotations around a fixed axis in one minute.
DVD:
Digital versatile disc.
Can store more data than CD by changing the light to red light.
Why the DVD can store more data by using red light?
Shorter wavelength when compared to infra red in electromagnetic spectrum.
Blu-ray:
More data than DVD.
Changing light to blue.
Advantages:
Cheap.
Reliable.
Fast to access data.
Disadvantages:
Damaged.
Small storage than DVD.