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It was resolved with both surviving however: DVD-R predominating for stand-alone DVD recorders and players, and (for computers) most DVD devices being engineered as dual format, to be compatible with both. As of 2007 DVD is the de facto standard for pre-recorded movies, and popular storage of data beyond the capacity of CD.
DVDs offer significantly higher storage capacity than compact discs (CD) while having the same dimensions. A standard single-layer DVD can store up to 4.7 GB of data, a dual-layer DVD up to 8.5 GB. Variants can store up to a maximum of 17.08 GB. [11]
An optical disc drive is a device in a computer that can read CD-ROMs or other optical discs, such as DVDs and Blu-ray discs. Optical storage differs from other data storage techniques that make use of other technologies such as magnetism , such as floppy disks and hard disks , or semiconductors , such as flash memory .
The CD-ROM itself may contain "weak" sectors to make copying the disc more difficult, and additional data that may be difficult or impossible to copy to a CD-R or disc image, but which the software checks for each time it is run to ensure an original disc and not an unauthorized copy is present in the computer's CD-ROM drive. [citation needed]
Disk storage is now used in both computer storage and consumer electronic storage, e.g., audio CDs and video discs (VCD, DVD and Blu-ray). Data on modern disks is stored in fixed length blocks, usually called sectors and varying in length from a few hundred to many thousands of bytes. Gross disk drive capacity is simply the number of disk ...
Optical discs can be reflective, where the light source and detector are on the same side of the disc, or transmissive, where light shines through the disc to be detected on the other side. Optical discs can store analog information (e.g. Laserdisc), digital information (e.g. DVD), or store both on the same disc (e.g. CD Video).
A live CD (also live DVD, live disc, or live operating system) is a complete bootable computer installation including operating system which runs directly from a CD-ROM or similar storage device into a computer's memory, rather than loading from a hard disk drive.
Paper data storage, e.g. punched cards, punched tapes (now obsolete) Examples of removable media that are standalone plug-and-play devices that carry their own reader hardwares include: USB flash drives [5] Portable storage devices. Dedicated external solid-state drives (SSD) Enclosured mass storage drives, i.e. modified hard disk drives (HDD ...