User:Tom94022/Sandbox2: Difference between revisions
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and so forth. |
and so forth. |
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The HDD industry practice of using suffixes assigned powers of 1000 to describe HDD capacity |
The HDD industry practice of using suffixes assigned powers of 1000 to describe HDD capacity dates back to the earliest days of computing |
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The Memory industry practice of using the same suffixes but assigned to powers of 1024 also dates back to the earliest days of computing. |
The Memory industry practice of using the same suffixes but assigned to powers of 1024 also dates back to the earliest days of computing. |
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Revision as of 21:45, 4 May 2011
Capacity measurements
| Advertised capacity by manufacturer (using decimal multiples) |
Expected capacity by consumers in class action (using binary multiples) |
Reported capacity | |||
|---|---|---|---|---|---|
| Windows (using binary multiples) |
Mac OS X 10.6+ (using decimal multiples) | ||||
| With prefix | Bytes | Bytes | Diff. | ||
| 100 MB | 100,000,000 | 104,857,600 | 4.86% | 95.4 MB | 100.0 MB |
| 100 GB | 100,000,000,000 | 107,374,182,400 | 7.37% | 93.1 GB, 95,367 MB | 100.00 GB |
| 1 TB | 1,000,000,000,000 | 1,099,511,627,776 | 9.95% | 931 GB, 953,674 MB | 1,000.00 GB |
The capacity of hard disk drives is given by manufacturers in megabytes (1 MB = 1,000,000 bytes), gigabytes (1 GB = 1,000,000,000 bytes) or terabytes (1 TB = 1,000,000,000,000 bytes).[1][2] This numbering convention, where prefixes like kilo- and mega- denote powers of 1000, is also used for data transmission rates and DVD capacities. However, the convention is different from that used in the memory industry (i.e., RAM and ROM) and for CDs where prefixes like kilo- and mega- denote capacity in powers of 1024.
When the unit prefixes like kilo- denote powers of 1024 math in the measure of computer capacities, the 1024n progression (for n = 1, 2, …) is as follows:[1]
- kilo = 210 = 10241 = 1024,
- mega = 220 = 10242 = 1,048,576,
- giga = 230 = 10243 = 1,073,741,824,
and so forth.
The HDD industry practice of using suffixes assigned powers of 1000 to describe HDD capacity dates back to the earliest days of computing
The Memory industry practice of using the same suffixes but assigned to powers of 1024 also dates back to the earliest days of computing.
There is really no reason for this difference besides it just being convention to use powers of 1024 in reporting memory size. The computer itself does not internally represent the HDD (or memory) capacity as being in powers of 1024[3]. Until the 1980s there was little confusion because the use of such these prefixes were generally consistent within articles, product literature and marketing materials while operating systems and utilities reported exact decimal HDD capacity as long strings of decimal digits, without prefixes. For unknown reasons, beginning in the 1980s, operating systems and or utilities began reporting HDD capacity using prefixes denoting powers of 1024. Altering this practice to use conventional powers of 1000 could have been done at any time, including from the beginning; however, for some reason it just stuck this way for most of the computing industry[3].
In the case of “mega-,” there is a nearly 5% difference between its decimal definition used by the HDD industry and the powers-of-two definition used by the semiconductor industry for memory. The difference is compounded by 2.4% with each incrementally larger prefix (gigabyte, terabyte, et cetera). This discrepancy between the two conventions for reporting capacity has led to confusion and litigation.
Different operating systems report HDD capacity in different ways. Most operating systems and associated utilities including Microsoft's Windows[4] use powers of 1024 prefixes to report HDD capacity. In such systems, an HDD specified by its manufacture as 1 TB would be reported as 931 GB leading to confusion over actual HDD capacity. Beginning August 2009 current versions of Apple's MacOS X operating system (version 10.6 and later) report HDD capacity using powers of 1000 prefixes and thereby avoids confusion as to HDD capacity by reporting capacity using the same symbols with the same meaning as the HDD industry.
Plaintiffs in two class action suits against HDD manufacturers argued that the use of decimal measurements effectively misled consumers (see Orin Safier v. Western Digital Corporation[5] and Cho v. Seagate Technology (US) Holdings, Inc.).[6]
In December 1998, an international standards organization attempted to address these dual definitions of the conventional prefixes by proposing unique binary prefixes and prefix symbols to denote multiples of 1024, such as “mebibyte (MiB)”, which exclusively denotes 220 or 1,048,576 bytes.[7] In the over‑25 years that have since elapsed, the proposal has seen little adoption by the computer industry and the conventionally prefixed forms of “byte” continue to denote slightly different values depending on context.[8][9]
- ^ a b Drive displays a smaller capacity than the indicated size on the drive label Cite error: The named reference "WD" was defined multiple times with different content (see the help page).
- ^ i.e. see HGST, Samsung, Seagate, Toshiba and Western Digital websites
- ^ a b Snow Leopard changes how file and drive sizes are calculated
- ^ Apple Macintosh operating systems prior to version 10.6 used powers of 1024 to report HDD capacity
- ^ Western Digital Settles Hard-Drive Capacity Lawsuit, Associated Press June 28, 2006 retrieved 2010 Nov 25
- ^ Seagate lawsuit concludes, settlement announced
- ^ National Institute of Standards and Technology. "Prefixes for binary multiples". "In December 1998 the International Electrotechnical Commission (IEC) [...] approved as an IEC International Standard names and symbols for prefixes for binary multiples for use in the fields of data processing and data transmission."
- ^ Upgrading and Repairing PCs, Scott Mueller, Pg. 596, ISBN 0789729741
- ^ The silicon web: physics for the Internet age, Michael G. Raymer, Pg. 40, ISBN 9781439803110