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Computers now have large hard drives, but external storage devices are still necessary for backup and security. Various devices have been used in the past, including CDs, DVDs, magnetic tape, and floppy disks. USB flash drives are now popular and can hold up to 256GB.
The standard in the 21st century is for computers to have a certain amount of storage space on their hard drives. Typical sizes are 160GB (gigabytes), 250GB, or 500GB. By the standards of the original hard drives in 1956 that could hold 5 megabytes (MB), these are gigantic. The size of applications and some file types, such as media files, however, mean that even these large hard drives can fill up quickly. Also, you often need to back up for security reasons. For these reasons, external storage solutions, sometimes referred to as secondary storage devices, are often used.
Over the years, a range of secondary storage devices have been devised and used. Some are much less popular in the present, including vacuum tubes, punched cards and punched tape, magnetic drums. Floppy disks, also called diskettes, both 5 1/4 inches (13.335 cm) and 3 1/2 inches (8.89 cm) came and went in the 20th century. Zip disks, which are similar in size to smaller floppies, survive and hold between 100 and 750MB of data, as does the REV disk, which holds up to 90GB of data. Magnetic tape endures as a storage device, having been used for over 50 years.
Various types of CDs and DVDs are commonly used secondary storage devices. Both are types of optical discs, written to and read by means of light. They are three types. Read-only examples include CDs, CD-ROMs, DVD-ROMs, and DVD-Videos. Examples of Write Once Read Many (WORM) include CR-R, DVD-R, DVD+R, and WORM. Finally, secondary optical storage devices include CD-RW, DVD-RAMS, DVD-RW, DVD+RW and MO.
Other storage devices include external hard drives. These can be mobile or desktop models. Some are made not only for storing, but also for streaming music, movies or photos to multimedia devices like Xbox 360® or PlayStation® 3.
USB flash drives come in many designs and can hold anywhere from 512MB to 256GB, the storage capacity of the Kingston® DataTraveler® 300, which the manufacturer claims is the world’s largest USB flash drive. These secondary storage devices are also known as flash drives, pen drives, pen drives, and by other names. Many USB flash drives are meant to be attached to a keychain or worn around your neck on a lanyard.
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