Giga-

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Giga- ( /ˈɡɪɡə/ or /ˈdʒɪɡə/ ) is a unit prefix in the metric system denoting a factor of a short-scale billion or long-scale milliard (109 or 1,000,000,000). It has the symbol G.

Contents

Giga- is derived from the Greek word γίγας (gígas), meaning "giant". The Oxford English Dictionary reports the earliest written use of giga in this sense to be in the Reports of the IUPAC 14th Conférence Internationale de Chimie in 1947: "The following prefixes to abbreviations for the names of units should be used: G giga 109×." [1] However, it was already used in 1932 by the German organization Verband deutscher Elektrotechniker. [2]

When referring to information units in computing, such as gigabyte, giga may sometimes mean 1073741824 (230); this causes ambiguity. Standards organizations discourage this and use giga- to refer to 109 in this context too. [3] [4] [ non-primary source needed ]Gigabit is only rarely used with the binary interpretation of the prefix. The binary prefix gibi has been adopted for 230, while reserving giga exclusively for the metric definition.

Pronunciation

In English, the prefix giga can be pronounced /ˈɡɪɡə/ (a hard g as in giggle), or /ˈdʒɪɡə/ (a soft g as in gigantic, which shares giga's Ancient Greek root). [5] A prominent example of this latter pronunciation is found in the pronunciation of gigawatts in the 1985 film Back to the Future .

According to the American writer Kevin Self, a German committee member of the International Electrotechnical Commission proposed giga as a prefix for 109 in the 1920s, drawing on a verse (evidently "Anto-logie") by the German humorous poet Christian Morgenstern that appeared in the third (1908) edition of his Galgenlieder (Gallows Songs). [6] [7] This suggests that a hard German [ɡ] was originally intended as the pronunciation. Self was unable to ascertain when the /dʒ/ (soft g) pronunciation came into occasional use, but claimed that as of 1995 it had returned to /ɡ/ (hard g). [8] [9]

In 1998, a poll by the phonetician John C. Wells found that 84% of Britons preferred the pronunciation of gigabyte starting with /ɡɪ/ (as in gig), 9% with /dʒɪ/ (as in jig), 6% with /ɡaɪ/ (guy), and 1% with /dʒaɪ/ (as in giant). [10]

Common usage

SI prefixes
PrefixBase 10 Decimal Adoption
[nb 1]
NameSymbol
quettaQ 1030 10000000000000000000000000000002022 [12]
ronnaR 1027 1000000000000000000000000000
yottaY 1024 10000000000000000000000001991
zettaZ 1021 1000000000000000000000
exaE 1018 10000000000000000001975 [13]
petaP 1015 1000000000000000
teraT 1012 10000000000001960
giga G 109 1000000000
mega M 106 10000001873
kilo k 103 10001795
hecto h 102 100
deca da 101 10
—— 100 1—
deci d 10−1 0.11795
centi c 10−2 0.01
milli m 10−3 0.001
micro μ 10−6 0.0000011873
nano n 10−9 0.0000000011960
picop 10−12 0.000000000001
femtof 10−15 0.0000000000000011964
attoa 10−18 0.000000000000000001
zeptoz 10−21 0.0000000000000000000011991
yoctoy 10−24 0.000000000000000000000001
rontor 10−27 0.0000000000000000000000000012022 [12]
quectoq 10−30 0.000000000000000000000000000001
Notes
  1. ↑ Prefixes adopted before 1960 already existed before SI. The introduction of the CGS system was in 1873.

Binary prefix

The notation 1 GB represents 1,000,000,000 bytes or, in deprecated usage, 1,073,741,824 (230) bytes. Per IEC 60027-2 A.2 and ISO/IEC 80000 standards, the correct notation of 230 is gibi (symbol Gi). [14] One gibibyte (1 GiB) is 1,073,741,824 bytes or 1.074 GB. Despite international standards, the use of 1 GB = 230 B is widespread. A laptop advertised as having 8 GB has 8,589,934,592 bytes of memory: 8.59×109 B, or 8 GiB. [15]

See also

Related Research Articles

The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as the Internet Protocol refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness.

A binary prefix is a unit prefix that indicates a multiple of a unit of measurement by an integer power of two. The most commonly used binary prefixes are kibi (symbol Ki, meaning 210 = 1024), mebi (Mi, 220 = 1048576), and gibi (Gi, 230 = 1073741824). They are most often used in information technology as multipliers of bit and byte, when expressing the capacity of storage devices or the size of computer files.

<span class="mw-page-title-main">Gigabyte</span> Unit of digital information

The gigabyte is a multiple of the unit byte for digital information. The prefix giga means 109 in the International System of Units (SI). Therefore, one gigabyte is one billion bytes. The unit symbol for the gigabyte is GB.

The kilobyte is a multiple of the unit byte for digital information.

Kilo is a decimal unit prefix in the metric system denoting multiplication by one thousand (103). It is used in the International System of Units, where it has the symbol k, in lowercase.

The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix mega is a multiplier of 1000000 (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes of information. This definition has been incorporated into the International System of Quantities.

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IEC 60027 is a technical international standard for letter symbols published by the International Electrotechnical Commission (IEC), comprising the following parts:

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An order of magnitude is usually a factor of ten. Thus, four orders of magnitude is a factor of 10,000 or 104.

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ISO/IEC 80000, Quantities and units, is an international standard describing the International System of Quantities (ISQ). It was developed and promulgated jointly by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). It serves as a style guide for using physical quantities and units of measurement, formulas involving them, and their corresponding units, in scientific and educational documents for worldwide use. The ISO/IEC 80000 family of standards was completed with the publication of the first edition of Part 1 in November 2009.

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This timeline of binary prefixes lists events in the history of the evolution, development, and use of units of measure that are germane to the definition of the binary prefixes by the International Electrotechnical Commission (IEC) in 1998, used primarily with units of information such as the bit and the byte.

In digital computing and telecommunications, a unit of information is the capacity of some standard data storage system or communication channel, used to measure the capacities of other systems and channels. In information theory, units of information are also used to measure information contained in messages and the entropy of random variables.

The gigabyte (GB) is 10003 bytes.

References

  1. ↑ "giga-, comb. form". Oxford English Dictionary. October 2011.
  2. ↑ "Wireless Engineer, 1932, issue 05, p. 252" (PDF). Archived (PDF) from the original on 2022-03-28. Retrieved 2022-03-28.
  3. ↑ "§3.1 SI prefixes". The International System of Units (SI) (PDF) (in French and English) (8th ed.). Paris: STEDI Media. 2006. p. 127. ISBN   92-822-2213-6. Archived (PDF) from the original on 2006-08-13. Retrieved 2007-02-25. [Side note:] These SI prefixes refer strictly to powers of 10. They should not be used to indicate powers of 2 (for example, one kilobit represents 1000 bits and not 1024 bits). The IEC has adopted prefixes for binary powers in the international standard IEC 60027-2: 2005, third edition, Letter symbols to be used in electrical technology — Part 2: Telecommunications and electronics. The names and symbols for the prefixes corresponding to 210, 220, 230, 240, 250, and 260 are, respectively: kibi, Ki; mebi, Mi; gibi, Gi; tebi, Ti; pebi, Pi; and exbi, Ei. Thus, for example, one kibibyte would be written: 1 KiB = 210 B = 1024 B, where B denotes a byte. Although these prefixes are not part of the SI, they should be used in the field of information technology to avoid the incorrect usage of the SI prefixes.
  4. ↑ NIST Guide for the Use of the International System of Units (Appendix D. ref 5)
  5. ↑ "SI prefixes and their etymologies". US Metric Association. Retrieved 27 November 2019.
  6. ↑ Morgenstern, Christian (1917). Galgenlieder nebst dem 'Gingganz' (in German). Illustrated by Karl Walser (22 ed.). Berlin, Germany: Bruno Cassirer. p. 52 – via Project Gutenberg. [First four lines:]Im Anfang lebte, wie bekannt, / als größter Säuger der Gig-ant. / Wobei gig eine Zahl ist, die / es nicht mehr gibt, - so groß war sie! [These lines are the only appearance of gig in the book. Gigant is German for "giant"; cf. "gigantic".]
  7. ↑ Morgenstern, Christian (1963). Gallows Songs: Christian Morgenstern's "Galgenlieder", Bilingual Edition: A Selection. Translated by Knight, Max. University of California Press. pp. 24–25. ISBN   9780520008847 . Retrieved 20 February 2016. [Translation:] Of yore, on earth was dominant / the biggest mammal: the Gig-ant. / ("Gig" is a numeral so vast, / it's been extinct for ages past.)
  8. ↑ Self, Kevin (October 1994). "Technically speaking". Spectrum. IEEE: 18.
  9. ↑ Self, Kevin (April 1995). "Technically speaking". Spectrum. IEEE: 16.
  10. ↑ Wells, J. C. (1998). LPD pronunciation preference poll 1998 .
  11. ↑ Wilcock, Bruce (July 1967). "Megayear and Gigayear". Nature. 215 (5096): 102–102. doi:10.1038/215102b0. ISSN   1476-4687.
  12. 1 2 "On the extension of the range of SI prefixes". 18 November 2022. Retrieved 5 February 2023.
  13. ↑ "Metric (SI) Prefixes". NIST.
  14. ↑ "Definitions of the SI units: The binary prefixes". physics.nist.gov. Retrieved 2023-04-05.
  15. ↑ "GB Vs GiB: What's The Difference? - MASV". massive.io. Retrieved 2024-08-08.
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