:heisenbug: /hi:'zen-buhg/ /n./ [from Heisenberg's
Uncertainty Principle in quantum physics] A bug that disappears or
alters its behavior when one attempts to probe or isolate it.
(This usage is not even particularly fanciful; the use of a
debugger sometimes alters a program's operating environment
significantly enough that buggy code, such as that which relies on
the values of uninitialized memory, behaves quite differently.)
Antonym of {Bohr bug}; see also {mandelbug},
{schroedinbug}. In C, nine out of ten heisenbugs result from
uninitialized auto variables, {fandango on core} phenomena
(esp. lossage related to corruption of the malloc {arena}) or
errors that {smash the stack}.
:Helen Keller mode: /n./ 1. State of a hardware or software system that is deaf, dumb, and blind, i.e., accepting no input and generating no output, usually due to an infinite loop or some other excursion into {deep space}. (Unfair to the real Helen Keller, whose success at learning speech was triumphant.) See also {go flatline}, {catatonic}. 2. On IBM PCs under DOS, refers to a specific failure mode in which a screen saver has kicked in over an {ill-behaved} application which bypasses the very interrupts the screen saver watches for activity. Your choices are to try to get from the program's current state through a successful save-and-exit without being able to see what you're doing, or to re-boot the machine. This isn't (strictly speaking) a crash.
:hello, sailor!: /interj./ Occasional West Coast equivalent of {hello, world}; seems to have originated at SAIL, later associated with the game {Zork} (which also included "hello, aviator" and "hello, implementor"). Originally from the traditional hooker's greeting to a swabbie fresh off the boat, of course.
:hello, wall!: /excl./ See {wall}.
:hello, world: /interj./ 1. The canonical minimal test message in the C/Unix universe. 2. Any of the minimal programs that emit this message. Traditionally, the first program a C coder is supposed to write in a new environment is one that just prints "hello, world" to standard output (and indeed it is the first example program in {K&R}). Environments that generate an unreasonably large executable for this trivial test or which require a {hairy} compiler-linker invocation to generate it are considered to {lose} (see {X}). 3. Greeting uttered by a hacker making an entrance or requesting information from anyone present. "Hello, world! Is the {VAX} back up yet?"
:hex: /n./ 1. Short for {{hexadecimal}}, base 16. 2. A 6-pack of anything (compare {quad}, sense 2). Neither usage has anything to do with {magic} or {black art}, though the pun is appreciated and occasionally used by hackers. True story: As a joke, some hackers once offered some surplus ICs for sale to be worn as protective amulets against hostile magic. The chips were, of course, hex inverters.
:hexadecimal:: /n./ Base 16. Coined in the early 1960s to replace earlier `sexadecimal', which was too racy and amusing for stuffy IBM, and later adopted by the rest of the industry.
Actually, neither term is etymologically pure. If we take `binary' to be paradigmatic, the most etymologically correct term for base 10, for example, is `denary', which comes from `deni' (ten at a time, ten each), a Latin `distributive' number; the corresponding term for base-16 would be something like `sendenary'. `Decimal' is from an ordinal number; the corresponding prefix for 6 would imply something like `sextidecimal'. The `sexa-' prefix is Latin but incorrect in this context, and `hexa-' is Greek. The word `octal' is similarly incorrect; a correct form would be `octaval' (to go with decimal), or `octonary' (to go with binary). If anyone ever implements a base-3 computer, computer scientists will be faced with the unprecedented dilemma of a choice between two *correct* forms; both `ternary' and `trinary' have a claim to this throne.
:hexit: /hek'sit/ /n./ A hexadecimal digit (0—9, and A—F or a—f). Used by people who claim that there are only *ten* digits, dammit; sixteen-fingered human beings are rather rare, despite what some keyboard designs might seem to imply (see {space-cadet keyboard}).
:HHOK: See {ha ha only serious}.