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==Definitions== The unit megabyte is commonly used for 1000<sup>2</sup> (one million) bytes or 1024<sup>2</sup> bytes. The interpretation of using base 1024 originated as technical jargon for the byte [[SI prefix|multiples]] that needed to be expressed by the powers of 2 but lacked a convenient name. As 1024 (2<sup>10</sup>) approximates 1000 (10<sup>3</sup>), roughly corresponding to the SI prefix [[kilo-]], it was a convenient term to denote the binary multiple. In 1999, the [[International Electrotechnical Commission]] (IEC) published standards for [[binary prefix]]es requiring the use of ''megabyte'' to denote 1000<sup>2</sup> bytes, and ''[[mebibyte]]'' to denote 1024<sup>2</sup> bytes. By the end of 2009, the IEC Standard had been adopted by the [[IEEE]], [[European Union|EU]], [[ISO]] and [[NIST]]. Nevertheless, the term megabyte continues to be widely used with different meanings. === Base 10 === : 1 MB = {{gaps|1|000|000}} bytes (= 1000<sup>2</sup> B = 10<sup>6</sup> B) is the definition following the rules of the [[International System of Units]] (SI), and the [[International Electrotechnical Commission]] (IEC).<ref name="NIST"/> This definition is used in [[computer network]]ing contexts and most [[storage media]], particularly [[hard drive]]s, [[Flash memory|flash]]-based storage,<ref>[https://web.archive.org/web/20080513155718/http://apac.sandisk.com/Products/Catalog(1349)-SanDisk_Extreme_Ducati_Edition_USB_Flash_Drive.aspx SanDisk USB Flash Drive] "Note: 1 megabyte (MB) = 1 million bytes; 1 gigabyte (GB) = 1 billion bytes."</ref> and [[DVD]]s, and is also consistent with the other uses of the [[SI prefix]] in computing, such as [[Megahertz#Megahertz in computing|CPU clock speeds]] or [[FLOPS|measures of performance]]. The [[Mac OS X]] 10.6 file manager is a notable example of this usage in software. Since [[Mac OS X Snow Leopard|Snow Leopard]], file sizes are reported in decimal units.<ref>{{cite web|url=http://support.apple.com/kb/TS2419 |title=How Mac OS X reports drive capacity |publisher=Apple Inc |date=2009-08-27 |access-date=2009-10-16}}</ref> In this convention, one thousand megabytes (1000 MB) is equal to one gigabyte (1 GB), where 1 GB is one billion bytes. === Base 2 === {{Main|Mebibyte}} : 1 MB = {{gaps|1|048|576}} bytes (= 1024<sup>2</sup> B = 2<sup>20</sup> B) is the definition used by [[Microsoft Windows]] in reference to [[computer memory]], such as [[random-access memory]] (RAM). This definition is synonymous with the unambiguous binary unit [[mebibyte]]. In this convention, one thousand and twenty-four megabytes (1024 MB) is equal to one gigabyte (1 GB), where 1 GB is 1024<sup>3</sup> bytes (i.e., 1 [[Gibibyte|GiB]]). === Mixed === : 1 MB = {{gaps|1|024|000}} bytes (= 1000Γ1024 B) is the definition used to describe the formatted capacity of the 1.44 MB {{gaps|3.5-inch}} HD [[floppy disk]], which actually has a capacity of {{gaps|1|474|560|bytes}}.<ref>[http://www.computernostalgia.net/articles/HistoryoftheFloppyDisk.htm Tracing the History of the Computer - History of the Floppy Disk]</ref> Randomly addressable semiconductor memory doubles in size for each address lane added to an integrated circuit package, which favors counts that are powers of two. The capacity of a disk drive is the product of the sector size, number of sectors per track, number of tracks per side, and the number of disk platters in the drive. Changes in any of these factors would not usually double the size.
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