CD-Rs

How do you add data to it?

Using a CD burner It has a smooth reflective metal layer, which

rests on top of a layer of photosensitive dye. When the disc is blank, the dye is translucent: Light can shine through and reflect off the metal surface. But when you heat the dye layer with concentrated light of a particular frequency and intensity, the dye turns opaque: It darkens to the point that light can't pass through. These darken spots would represent spots where the bumps would be in a conventional CD, forming non-reflecting areas.

How do you read data from it? Like a CD, the darken spots on the CD-R

represents Bumps on a CD. While spinning in the CD Player, a laser is shone on it. The darken spots cannot reflect laser and thus acts like a bump which reflects the laser off the optical pickup. The spots that are not darken by the burning would reflect the laser directly into the optical pickup which converts data into understandable data blocks.

When do you use it ?

When you want to burn some music/videos onto a disc.

When you want a temporary portable storage (small though).

Is it serial or direct access?

Direct

Is it solid state or does it have moving parts?

Solid state but it rotates in the cd player.

How much data can it store ?

650mb – 1.2gb

How long will it last in years ?

75 years (cyanine dye, used in "green" discs)

100 years (phthalocyanine dye, used in "gold" discs)

200 years ("advanced" phthalocyanine dye, used in "platinum" discs)

How much does it cost ?

Up to as low as $0.20 per disc

How much does it cost per megabyte?

Um … 0.2 / 650 = ?

Answer = $0.000030769

DvD-R

How do you add data to it?

Data on a DVD is encoded in the form of small pits and bumps in the track of the disc.

How do you read data from it? Like CDs, the bumps will appear as pits on the

aluminum side however from the side that the laser reads them on, they are bumps

When do you use it?

For storage (7 times more than a typical cd-r)

For storing higher quality movies/songs that require a bigger space.

Is it serial or direct access?

Direct

Is it solid state or does it have moving parts?

Similar to a CD in a way that it is also a Solid state that rotates in the DVD player.

How much data can it store?

Single-sided/single-layer 4.38 GB Single-sided/double-layer 7.95 GB Double-sided/single-layer 8.75 GB Double-sided/double-layer 15.9 GB

How long will it last in years?

Dye-based DVD-R and DVD+R discs is anywhere from 20 to 250 years.

However the phase-change erasable formats (DVD-RAM, DVD-RW, and DVD+RW) have an expected lifetime of 25 to 100 years.

How much does it cost?

DVD+R / DVD-R (writable DVD blanks) generally cost between $0.30 - $2.00 per disc.

How much does it cost per megabyte? Single-sided/single-layer 4.38 GB

0.30/4380 = $0.0000684 2.00/4380 = $0.0004566

Single-sided/double-layer 7.95 GB 0.30/7950 = $0.0000377 2.00/7950 = $0.0002515

Double-sided/single-layer 8.75 GB 0.30/8750 = $0.0000342 2.00/8750 = $0.0002285

Double-sided/double-layer 15.9 GB 0.30/15900 = $0.0000188 2.00/15900 = $0.0001257

Blu-Ray Discs

How do you add data to it?

Discs store digitally encoded video and audio information in pits like a DVD.

How do you read data from it? Unlike current DVDs, which use a red laser to

read and write data, Blu-ray uses a blue laser (which is where the format gets its name). A blue laser has a shorter wavelength (405 nanometers) than a red laser (650 nanometers). The smaller beam focuses more precisely, enabling it to read information recorded in pits that are only 0.15 microns (µm) (1 micron = 10-6 meters) long -- this is more than twice as small as the pits on a DVD.

When do you use it?

When you want to record high-definition television (HDTV) without any quality loss

When you want to instantly skip to any spot on the disc When you want torecord one program while watching

another on the disc When you want to create playlists When you want to edit or reorder programs recorded on the

disc When you want to automatically search for an empty space

on the disc to avoid recording over a program When you want to access the Web to download subtitles and

other extra features Storage device

Is it serial or direct access?

Direct

Is it solid state or does it have moving parts?

Similar to a CD-R and DVD-R, it is a solid state that rotates in a blu-ray disc/DVD player.

How much data can it store?

Single layer blu-ray disc 27GB Double layer blu-ray disc 54GB

How long will it last in years?

Anywhere from 30 to 50 years.

How much does it cost?

From as low as $8 to $15 per disc

How much does it cost per megabyte?

Single layer blu-ray disc 27GB8.00/27000 = $0.000296215.00/27000 = $0.0005555

Double layer blu-ray disc 54GB8.00/54000 = $0.000148115.00/54000 = $0.0002777