Giga-

Giga- ( or ) 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.

''Giga-'' is derived from the Greek word (''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×." However, it was already used in 1932 by the German organization ''Verband deutscher Elektrotechniker''.

When referring to information units in computing, such as gigabyte, giga may sometimes mean (2³⁰); this causes ambiguity. Standards organizations discourage this and use giga- to refer to 10⁹ in this context too.NIST Guide for the Use of the International System of Units (Appendix D. ref 5)
/ref> ''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 (a hard ''g'' as in ''giggle''), or (a soft ''g'' as in ''gigantic'', which shares ''giga'' Ancient Greek root). 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 (Gallows Songs). This suggests that a hard German was originally intended as the pronunciation. Self was unable to ascertain when the (soft ''g'') pronunciation came into occasional use, but claimed that as of 1995 it had returned to (hard ''g'').

In 1998, a poll by the phonetician John C. Wells found that 84% of Britons preferred the pronunciation of ''gigabyte'' starting with (as in ''gig''), 9% with (as in ''jig''), 6% with (''guy''), and 1% with (as in ''giant'').

Common usage

* gigahertz— clock rate of a CPU, for instance, 3 GHz =
* gigabit— bandwidth of a network link, for instance, 1 Gbit/s = .
* gigabyte—for instance, for hard disk capacity, 120 GB = ;
* gigayear or gigaannum—one billion (10⁹) years, sometimes abbreviated Gyr, but the preferred usage is Ga or, for ''years ago'', GA.

Binary prefix

The notation 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). One gibibyte () is 1,073,741,824 bytes or . Despite international standards, the use of = 2³⁰ B is widespread. A laptop advertised as having has 8,589,934,592 bytes of memory: , or .

See also

* Binary prefix
* Gigabit Ethernet
* SI prefix
* List of commonly used taxonomic affixes
* RKM code

References

External links

{{wiktionary, giga-

BIPM website

SI prefixes

he:תחיליות במערכת היחידות הבינלאומית#גיגה