(Redirected from Giga)
:''For the Baroque dance, see ''
gigue''. For the television station, see ''
GIGA Television''.''
'giga-' (symbol: ''G'') is a
prefix in the
SI system of units denoting
109, or 1,000,000,000 (1 thousand million). The ''
Oxford English Dictionary'' reports the earliest written use of giga- in this sense to be in the Reports of the
IUPAC 14th Conference in 1947: "The following prefixes to abbreviations for the names of units should be used..G giga- 10
9×". Giga- comes from the
Greek γίγας, meaning ''.
When referring to
computing information units, such as
gigabit or
gigabyte, ''giga-'' can sometimes mean 1,073,741,824 (2
30), but can also denote 1,000,000,000 (10
9). The exact definition being used is ambiguous, and must be determined from context. The binary prefix
gibi- has been standardized for 2
30, while reserving giga- exclusively for 10
9, to resolve this ambiguity, but has yet to achieve widespread usage. See
Binary prefix.
Pronunciation
In
English the initial G of ''giga'' can be pronounced with a soft G (as in ''gigantic'') or with a hard G (as in ''giggle''). According to the American writer Self, in the 1920s a German committee member of the
International Electrotechnical Commission proposed giga- as a prefix for 10
9, drawing on a verse by the humorous poet Christian Morgenstern that appeared in the third (1908) edition of ''Galgenlieder'' (Gallows Songs). This suggests a hard German ''g'' was originally intended as the pronunciation. Self was unable to ascertain at what point the soft ''g'' pronunciation became accepted, but as of 1995 current practice had returned to hard ''g''.
[1] A prominent example of the soft G pronunciation is found in the
1985 movie ''
Back to the Future'', where ''gigawatts'' was pronounced as ''jigawatts''.
Common usage
★
gigabyte — for instance, in
hard disk capacity, 120 GB = 120,000,000,000 bytes; in file sizes, 1 GB = 1,073,741,824 bytes (also termed a
gibibyte to reduce ambiguity)
★
gigahertz —
clock rate of a
CPU, for instance, 3 GHz = 3,000,000,000
Hz
★
gigabit —
bandwidth of a
network, for instance, 1 Gbit = 1,000,000,000
bit/s
★
gigayear or
gigaannum — one billion (
) complete
Julian rotation periods of the Earth about the
Sun. (sometimes abbr. Gyr, but the preferred usage is Ga)
See also
★
SI prefix
★
Binary prefix
★
gibibyte
★
Gigabit Ethernet
Notes and References
1. Kevin Self. (April 1995). "Technically speaking". ''Spectrum''.
External links
★
BIPM website