In techspeak and jargon, the standard metric

prefixes used in the SI (Système International) conventions for

scientific measurement have dual uses. With units of time or

things that come in powers of 10, such as money, they retain their

usual meanings of multiplication by powers of 1000 = 10^3.

But when used with bytes or other things that naturally come in

powers of 2, they usually denote multiplication by powers of

1024 = 2^(10).

Here are the SI magnifying prefixes, along with the corresponding

binary interpretations in common use:

prefix decimal binary

kilo- 1000^1 1024^1 = 2^10 = 1,024

mega- 1000^2 1024^2 = 2^20 = 1,048,576

giga- 1000^3 1024^3 = 2^30 = 1,073,741,824

tera- 1000^4 1024^4 = 2^40 = 1,099,511,627,776

peta- 1000^5 1024^5 = 2^50 = 1,125,899,906,842,624

exa- 1000^6 1024^6 = 2^60 = 1,152,921,504,606,846,976

zetta- 1000^7 1024^7 = 2^70 = 1,180,591,620,717,411,303,424

yotta- 1000^8 1024^8 = 2^80 = 1,208,925,819,614,629,174,706,176

Here are the SI fractional prefixes:

prefix decimal jargon usage

milli- 1000^-1 (seldom used in jargon)

micro- 1000^-2 small or human-scale (see micro-)

nano- 1000^-3 even smaller (see nano-)

pico- 1000^-4 even smaller yet (see pico-)

femto- 1000^-5 (not used in jargon---yet)

atto- 1000^-6 (not used in jargon---yet)

zepto- 1000^-7 (not used in jargon---yet)

yocto- 1000^-8 (not used in jargon---yet)

The prefixes zetta-, yotta-, zepto-, and yocto- have been included

in these tables purely for completeness and giggle value; they were

adopted in 1990 by the `19th Conference Generale des Poids et

Mesures'. The binary peta- and exa- loadings, though well

established, are not in jargon use either -- yet. The prefix

milli-, denoting multiplication by 1/1000, has always

been rare in jargon (there is, however, a standard joke about the

`millihelen' -- notionally, the amount of beauty required to

launch one ship). See the entries on micro-, pico-, and

nano- for more information on connotative jargon use of these

terms. `Femto' and `atto' (which, interestingly, derive not

from Greek but from Danish) have not yet acquired jargon loadings,

though it is easy to predict what those will be once computing

technology enters the required realms of magnitude (however, see

attoparsec).

There are, of course, some standard unit prefixes for powers of

10. In the following table, the `prefix' column is the

international standard suffix for the appropriate power of ten; the

`binary' column lists jargon abbreviations and words for the

corresponding power of 2. The B-suffixed forms are commonly used

for byte quantities; the words `meg' and `gig' are nouns that may

(but do not always) pluralize with `s'.

prefix decimal binary pronunciation

kilo- k K, KB, /kay/

mega- M M, MB, meg /meg/

giga- G G, GB, gig /gig/,/jig/

Confusingly, hackers often use K or M as though they were suffix or

numeric multipliers rather than a prefix; thus "2K dollars", "2M

of disk space". This is also true (though less commonly) of G.

Note that the formal SI metric prefix for 1000 is `k'; some use

this strictly, reserving `K' for multiplication by 1024 (KB is

thus `kilobytes').

K, M, and G used alone refer to quantities of bytes; thus, 64G is

64 gigabytes and `a K' is a kilobyte (compare mainstream use of

`a G' as short for `a grand', that is, $1000). Whether one

pronounces `gig' with hard or soft `g' depends on what one thinks

the proper pronunciation of `giga-' is.

Confusing 1000 and 1024 (or other powers of 2 and 10 close in

magnitude) -- for example, describing a memory in units of

500K or 524K instead of 512K -- is a sure sign of the

marketroid. One example of this: it is common to refer to the

capacity of 3.5" microfloppies as `1.44 MB' In fact, this is a

completely bogus number. The correct size is 1440 KB, that

is, 1440 * 1024 = 1474560 bytes. So the `mega' in `1.44 MB' is

compounded of two `kilos', one of which is 1024 and the other of

which is 1000. The correct number of megabytes would of course be

1440 / 1024 = 1.40625. Alas, this fine point is probably lost on

the world forever.

[1993 update: hacker Morgan Burke has proposed, to general

approval on Usenet, the following additional prefixes:

groucho

10^(-30)

harpo

10^(-27)

harpi

10^(27)

grouchi

10^(30)

We observe that this would leave the prefixes zeppo-, gummo-, and

chico- available for future expansion. Sadly, there is little

immediate prospect that Mr. Burke's eminently sensible proposal

will be ratified.]

[1999 upate: there is an

IEC proposal for binary multipliers, but no

its proposals are in live use.]

- bit-paired keyboard n.,obs.
(alt. `bit-shift
keyboard') A non-standard keyboard layout that seems to have
originated with the Teletype ASR-33 and remained common for several
years on early computer equipment.

The ASR-33 was a mechanical device (see EOU), so the only way to generate the character codes from keystrokes was by some physical linkage.... - micro-: pref. 1. Very small; this is the root of its use as a
quantifier prefix.

2. A quantifier prefix, calling for multiplication by 10^(-6) (see {{quantifiers}}).... - micro- pref.
1. Very small; this is the root of its use as
a quantifier prefix.

2. A quantifier prefix, calling for multiplication by 10^(-6) (see quantifiers).... - 1 Billion dollars of budget deficit = 1 Gramm-Rudman
6.

023 x 10 to the 23rd power alligator pears = Avocado's number 2 pints = 1 Cavort Basic unit of Laryngitis = The Hoarsepower Shortest distance between two jokes = A straight line 6 Curses = 1 Hexahex 3500 Calories = 1 Food Pound 1 Mole = 007 Secret Agents 1 Mole = 25 Cagey Bees 1 Dog Pound = 16 oz.... - bignum /big'nuhm/ n.
[common; orig. from MIT MacLISP]
1.

[techspeak] A multiple-precision computer representation for very large integers.... - attoparsec: n. About an inch. `atto-' is the standard SI
prefix for multiplication by 10^(-18).

A parsec (parallax-second) is 3.26 light-yea... - attoparsec n.
About an inch. `atto-' is the standard SI
prefix for multiplication by 10^(-18).

A parsec (parallax-second) is 3.26 light-yea... - ybble /nib'l/ (alt. `nibble') n.
[from v.
`nibble' by analogy with `bite' =&g

`byte'] Four bits; one hex digit; a half-byte. Though `byte' is now techspeak, this useful relative is still jargon.... - mumble interj.
1. Said when the correct response is too
complicated to enunciate, or the speaker has not thought it out.

Often prefaces a longer answer, or indicates a general reluctance to get into a long discussion....