Hey Computer Engineers' u can get 10 pts for this question!!!?

Question

Why does a DVD have more storage capacity while its just similar to the CD?
thank you 4 ur answers....

Answer 1

a cd stores the information in round pattern whereas a dvd stores it in round, horizontal, and vertical patterns. some dvds also have layers but they are very costly.

Answer 2

Although the physical appearance of the two media. ie CD disk, and DVD disk, are basically the same, the real differences lie in the R/RW read/record devices.

The DVD has a higher density laser recording pattern and records and reads in a layered concept which promotes higher digital quality in both video and audio creation and reproduction.

Watch for even higher tech developments via the new blue laser technology which will be nothing short of sensory overload.

Excellent question,

Darryl S.

Answer 3

Hi!

The DVD is more compact than a CD when it comes to data storage. Since the laser beam that burns the DVD is MUCH thinner than the ones used for CD burning, this allows for more "holes" (read bits) to be placed on the same surface.
Think of it this way: on a certain surface you can place a certain amount of soccer balls. On the same surface, however, you can place many more golf balls.

I hope I've helped!

Answer 4

there are more layers on a dvd than a cd DVD offers between 7 and 25 x the storage capacity of CD depending on how many information layers are on the disc.



CDs and DVDs consist of the same basic materials and layers but are manufactured differently. A DVD is actually like two thin CDs glued together. A CD is read from and written to (by laser) on one side only; a DVD can be read from or written to on one or both sides, depending on how the disk was manufactured. Recordable DVDs (DVD-R, DVD-RW, DVD-RAM) can be manufactured with one re-cording layer on each side. Prerecorded DVDs (DVD-ROM) can be manufactured with one or two recorded layers on each side.

The polycarbonate substrate makes up most of the disk, including the area that is read by the laser (opposite the label side on CDs). It is present on both sides of a DVD, even a “single-sided” disk with a label on one side.the data layer of CDs and DVDs is the layer that contains the data. The data appear as marks or pits that either absorb light from the laser beam, or transmit the light back to the laser photosensor by way of the metal reflective layer. In CDs, the data and metal layers are very close to the top of the disk (label side); in DVDs, they are in the middle of the disk . The types of data and metal layers used depend on the type of disk.

Answer 5

The larger storage capacity of a DVD-R compared to a CD-R is achieved through smaller pit size and smaller track pitch of the groove spiral which guides the laser beam. Consequently, more pits can be written on the same physical sized disc. In order to write smaller pits onto the recording dye layer (see CD-R) a red laser beam with a wavelength of 650 nm (for general use recordable DVD) is used in conjunction with a higher numerical aperture lens. Because of this shorter wavelength, DVD-R and DVD+R use different dyes from CD-R to properly absorb this wavelength.

DVD-R discs are composed of two 0.6 mm polycarbonate discs, bonded with an adhesive to each other. One contains the laser guiding groove and is coated with the recording dye and a silver alloy or gold reflector. The other one (for single-sided discs) is an ungrooved "dummy" disc to assure mechanical stability of the sandwich structure, and compatibility with the compact disc standard geometry which requires a total disc thickness of about 1.2 mm. Double-sided discs have two grooved, recordable disc sides, and require the user to flip the disc to access the other side. Compared to a CD's 1.2 mm of polycarbonate, a DVD's laser beam only has to penetrate 0.6 mm of plastic in order to reach the dye recording layer, which allows the lens to focus the beam to a smaller spot size to write smaller pits.

In a DVD-R, the addressing (the determination of location of the laser beam on the disc) is done with additional pits and lands (called land pre-pits) in the areas between the grooves. The groove on a DVD-R disc has a constant wobble frequency used for motor control etc.
Hope this answer it

Answer 6

Open the control panel and look for Regional and Language Options. You may have to download the French language files from Microsoft if they were not already loaded. If you select French and the files are not loaded, Windows may go to Windows Update and download them for you. Before you start put your OS CD in the driver. French is already installed on your comp. Control Panel - Regional and Language Options - change language in Select an item… to French. You have to check all options in all folders in this menu. In Languages click on Details and click on Add. Here choose French as a Default Input language, then click on Add and add French. In Advanced again choose French. In other words, where you see English change it to French. Then OK and Apply.

Answer 7

the cd and dvd are diffent due to what they are made out of. A cd is not a mass storeage divice whlie the dvd is. that's why the dvd holds more data.

Answer 8

Because DVD's density is bigger than CDs. There's a little differencies. Density and track structures.

Recordable CD & DVD drives have become a must-have for home computers. More and more machines are including CD or DVD writer drives as a standard feature, and fast, affordable drives are easily available for machines without.

However, there's some question about new recordable DVD formats. There are no fewer than seven DVD formats, each with different specs and drive requirements — and not all of them are intended for computing.

Still, one common question is how any of these DVD formats varies from the writeable CD formats. Although DVD and CD media and drives have the same form factor (media size and shape), that's where the similarities end. DVD media has at least seven times the capacity of CD media — a feat partially accomplished by using multiple recording layers and recording on both sides of the media. The write method also helps boost the capacity of DVD.

Data pits & lasers
Like CDs, DVDs store data in microscopic grooves running in a spiral around the disc. All DVD drive types use laser beams to scan these grooves: Minuscule reflective bumps (called lands) and nonreflective holes (called pits) aligned along the grooves represent the zeros and ones of digital information.

DVD technology writes in smaller "pits" to the recordable media than CD technology. Smaller pits mean that the drive's laser must produce a smaller spot. DVD technology achieves this by reducing the laser's wavelength from the 780nm infrared light used in standard CD drives to 625nm to 650nm red light.

Smaller data pits allow more pits per data track. The minimum pit length of a single layer DVD-RAM is 0.4 micron as compared to 0.834 micron for a CD. Additionally, DVD tracks are closer together, allowing more tracks per disc. Track pitch-the distance from the center of one part of the spiral information or "track" to the adjacent part of the track-is smaller. On a 3.95GB DVD-R, track pitch is 0.8 microns; CD track pitch is 1.6 microns. On 4.7GB DVD-R media, an even smaller track pitch of 0.74 microns helps boost storage capacity.

These narrow tracks require special lasers for reading and writing — which can't read CD-ROMs, CD-Rs, CD-RWs, or audio CDs. DVD-ROM drive makers solved the problem by putting two lasers in their drives: One for DVDs, the other for CDs.

Layers
To facilitate the focusing of the laser on smaller pits, DVD media uses a thinner plastic substrate than do CDs. This reduces the depth of the layer that the laser must pass through to reach the pits to record or read data. This reduction originally resulted in disks that were 0.6mm thick — half the thickness of a CD.

Even single-sided DVDs have two substrates, even though one isn't capable of holding data. Double-sided discs with two data surfaces must be turned over (much like old vinyl records!) to read data on each side.

Data access speeds
DVD accesses data faster than CD and uses more robust error correction. In fact, the speed of DVD demands a new unit of measure. CD drive speeds are expressed as multiples of that format's original data transfer rate "X," or 150KB per second. A 32X CD-ROM drive reads data at 32 times 150KBps or 4MBps. DVD's 1X is a blistering 1.38MBps. That's faster than an 8x CD drive.

Universal Data Format (UDF)
Another big difference between DVD recording and CD recording is the recording format. DVD recording uses UDF — Universal Data Format. UDF makes it possible to store data, video, audio, or a mix of all three within a single physical file structure. This file structure ensures that any file can be accessed by any drive, computer, or consumer video. UDF includes the CD-standard ISO 9660 compatibility, but CDs do not comply with UDF.

Answer 9

the density of data is different... it's just a more precise technology... based on the same principle... it's like the difference between screen resolutions... the bigger the resolution the smaller the pixel

Answer 10

because of the layers a dvd has more than a cd