CD vs DVD
Summary: Difference Between CD and DVD is that CD or also known as COMPACT DISC is small and portable round medium disc made of Molded Polymer used for storing data or information electronically. While DVD stores data, instructions, and information in a slightly different manner and thus achieves a higher storage capacity.
A CD or also known as COMPACT DISC is small and portable round medium disc made of Molded Polymer used for storing data or information electronically. The Size of Compact Disc is closed to Floppy disk, but you can store audio files, pictures, videos, text and other data too in CD electronically. You can also save other information as well in Digital Form. Tape Cartridges have been replaced by CDs because now people keep CD to play music at home instead of tape cartridges. Initially CDs were only Read-Only type, user can’t write the data on it but can read the Data saved in CDs. But now, users can record data in CD’s too. The process of writing data electronically can only be done by CD-R or CD-RW.
A CD-ROM, or compact disc read-only memory, is a type of optical disc that users can read but not write (record) or erase — hence, the name read-only. Manufacturers write the contents of standard CD-ROMs. A standard CD-ROM is called a single-session disc because manufacturers write all items on the disc at one time. Software manufacturers often distribute programs using CD-ROMs. A typical CD-ROM holds from 650 MB to 1 GB of data, instructions, and information. To read a CD-ROM, insert the disc in a CD-ROM drive or a CD-ROM player. Because audio CDs and CD-ROMs use the same laser technology, you may be able to use a CD-ROM drive to listen to an audio CD while using the computer.
Many people use archive discs or Picture CDs to preserve their photos. When you post and share photos online on a photo sharing community, you can choose to save your collection of online photos on an archive disc, which stores photos in the jpg file format. The cost of archive discs is determined by the number of photos being stored. One service, for example, charges $9.99 for the first hundred pictures.
Although the size and shape of a CD and DVD are similar, a DVD stores data, instructions, and information in a slightly different manner and thus achieves a higher storage capacity. DVD quality also far surpasses that of CDs because images are stored at higher resolution. A DVD-ROM (digital versatile disc-read-only memory or digital video disc-read-only memory) is a high-capacity optical disc on which users can read but not write or erase. Manufacturers write the contents of DVD-ROMs and distribute them to consumers. DVD-ROMs store movies, music, huge databases, and complex software.
To read a DVD-ROM, you need a DVD-ROM drive or DVD player. Most DVD-ROM drives also can read audio CDs, CD-ROMs, CD-Rs, and CD-RWs. Some drives, called DVD/CD-RW drives, are combination drives that read and write DVD and CD media. Many of today’s computers include these combination drives.
A DVD-ROM uses one of three storage techniques. The first involves making the disc denser by packing the pits closer together. The second involves using two layers of pits. For this technique to work, the lower layer of pits is semitransparent so that the laser can read through it to the upper layer. This technique doubles the capacity of the disc. Finally, some DVD-ROMs are double-sided.
A newer, more expensive DVD format is Blu-ray, which is a higher capacity and better quality than standard DVDs, especially for high-definition audio and video. A Blu-ray Disc (BD) has storage capacities of 100 GB, with expectations of exceeding 200 GB in the future. Blu-ray Disc drives and players are backward compatible with DVD and CD formats. Figure 6-25 compares the current storage capacities of DVD and Blu-ray media. Another high density format, called HD VMD (Versatile Multilayer Disc) potentially will contain up to 20 layers, each with a capacity of 5 GB. Current HD VMDs have capacities of 40 GB and more.
A mini-DVD that has grown in popularity is the UMD, which works specifically with the PlayStation Portable (PSP) handheld game console. The UMD (Universal Media Disc), which has a diameter of about 2.4 inches, can store up to 1.8 GB of games, movies, or music. Similarly, the mini Blu-ray Disc, which is used primarily in digital video recorders, stores approximately 7.5 GB.