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A USB flash drive, also known under a variety of other names, is a data storage device that includes flash memory with an integrated USB interface. USB flash drives are typically removable and rewritable, and physically much smaller than an optical disc. Most weigh less than .〔(Frequently Asked Questions About USB Flash Drives ). Peripherals.about.com (2010-06-17). Retrieved on 2011-05-18.〕 , drives of up to 512 gigabytes (GB) were available. A one-terabyte (TB) drive was unveiled at the 2013 Consumer Electronics Show and became available later that year. Storage capacities as large as 2 TB are planned, with steady improvements in size and price per capacity expected. Some allow up to 100,000 write/erase cycles, depending on the exact type of memory chip used, and have a 10-year shelf storage time.〔(【引用サイトリンク】url=http://www.allmemorycards.com/glossary/reliability.htm )〕〔 (AboutCom-Swivel-Pro-Flash "Imation Swivel Pro Flash Drive" ), About.com, 2008〕〔USB flash drives allow reading, writing, and erasing of data, with some allowing 1 billion write/erase cycles in each cell of memory: if 100 uses per day, 1 billion cycles could span 10,000 days or over 27 years. Some devices level the usage by auto-shifting activity to underused sections of memory.〕 USB flash drives are often used for the same purposes for which floppy disks or CDs were used, i.e., for storage, data back-up and transfer of computer files. They are smaller, faster, have thousands of times more capacity, and are more durable and reliable because they have no moving parts. Additionally, they are immune to electromagnetic interference (unlike floppy disks), and are unharmed by surface scratches (unlike CDs). Until about 2005, most desktop and laptop computers were supplied with floppy disk drives in addition to USB ports, but floppy disk drives have become obsolete with widespread adoption of USB ports and the magnitude of USB drive capacity over the 1.44MB 3.5 in. floppy disk. USB flash drives use the USB mass storage device class standard, supported natively by modern operating systems such as Windows, Linux, and other Unix-like systems, as well as many BIOS boot ROMs. USB drives with USB 2.0 support can store more data and transfer faster than much larger optical disc drives like CD-RW or DVD-RW drives and can be read by many other systems such as the Xbox 360, PlayStation 3, DVD players, automobile entertainment systems, and in a number of handheld devices such as smartphones and tablet computers, though the electronically similar SD card is better suited for those devices. A flash drive consists of a small printed circuit board carrying the circuit elements and a USB connector, insulated electrically and protected inside a plastic, metal, or rubberized case which can be carried in a pocket or on a key chain, for example. The USB connector may be protected by a removable cap or by retracting into the body of the drive, although it is not likely to be damaged if unprotected. Most flash drives use a standard type-A USB connection allowing connection with a port on a personal computer, but drives for other interfaces also exist. USB flash drives draw power from the computer via the USB connection. Some devices combine the functionality of a portable media player with USB flash storage; they require a battery only when used to play music. ==History== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「USB flash drive」の詳細全文を読む スポンサード リンク
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