atomic adj.
[from Gk. `atomos', indivisible] 1. Indivisible; cannot be
split up. For example, an instruction may be said to do several
things `atomically', i.e., all the things are done immediately,
and there is no chance of the instruction being half-completed or
of another being interspersed. Used esp. to convey that an
operation cannot be screwed up by interrupts. "This routine locks
the file and increments the file's semaphore atomically." 2.
[primarily techspeak] Guaranteed to complete successfully or not
at all, usu. refers to database transactions. If an error
prevents a partially-performed transaction from proceeding to
completion, it must be "backed out," as the database must not be
left in an inconsistent state.
Computer usage, in either of the above senses, has none of the
connotations that `atomic' has in mainstream English (i.e. of
particles of matter, nuclear explosions etc.).
Node:attoparsec, Next:AUP, Previous:atomic, Up:= A
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attoparsec n.
About an inch. `atto-' is the standard SI prefix for
multiplication by 10^(-18). A parsec (parallax-second) is 3.26
light-years; an attoparsec is thus 3.26 * 10^(-18) light years,
or about 3.1 cm (thus, 1 attoparsec/microfortnight equals about 1
inch/sec). This unit is reported to be in use (though probably
not very seriously) among hackers in the U.K. See micro-.