The Jargon File, Version 4.0.0, 24 Jul 1996

:abbrev: /*-breev'/, /*-brev'/ /n./ Common abbreviation for `abbreviation'.

:ABEND: /a'bend/, /*-bend'/ /n./ [ABnormal END] Abnormal termination (of software); {crash}; {lossage}. Derives from an error message on the IBM 360; used jokingly by hackers but seriously mainly by {code grinder}s. Usually capitalized, but may appear as `abend'. Hackers will try to persuade you that ABEND is called `abend' because it is what system operators do to the machine late on Friday when they want to call it a day, and hence is from the German `Abend' = `Evening'.

:accumulator: /n. obs./ 1. Archaic term for a register. On-line use of it as a synonym for `register' is a fairly reliable indication that the user has been around for quite a while and/or that the architecture under discussion is quite old. The term in full is almost never used of microprocessor registers, for example, though symbolic names for arithmetic registers beginning in `A' derive from historical use of the term `accumulator' (and not, actually, from `arithmetic'). Confusingly, though, an `A' register name prefix may also stand for `address', as for example on the Motorola 680x0 family. 2. A register being used for arithmetic or logic (as opposed to addressing or a loop index), especially one being used to accumulate a sum or count of many items. This use is in context of a particular routine or stretch of code. "The FOOBAZ routine uses A3 as an accumulator." 3. One's in-basket (esp. among old-timers who might use sense 1). "You want this reviewed? Sure, just put it in the accumulator." (See {stack}.)

:ACK: /ak/ /interj./ 1. [from the ASCII mnemonic for 0000110] Acknowledge. Used to register one's presence (compare mainstream Yo!). An appropriate response to {ping} or {ENQ}. 2. [from the comic strip "Bloom County"] An exclamation of surprised disgust, esp. in "Ack pffft!" Semi-humorous. Generally this sense is not spelled in caps (ACK) and is distinguished by a following exclamation point. 3. Used to politely interrupt someone to tell them you understand their point (see {NAK}). Thus, for example, you might cut off an overly long explanation with "Ack. Ack. Ack. I get it now".

There is also a usage "ACK?" (from sense 1) meaning "Are you there?", often used in email when earlier mail has produced no reply, or during a lull in {talk mode} to see if the person has gone away (the standard humorous response is of course {NAK} (sense 2), i.e., "I'm not here").

:Acme: /n./ The canonical supplier of bizarre, elaborate, and non-functional gadgetry -- where Rube Goldberg and Heath Robinson shop. Describing some X as an "Acme X" either means "This is {insanely great}", or, more likely, "This looks {insanely great} on paper, but in practice it's really easy to shoot yourself in the foot with it." Compare {pistol}.

This term, specially cherished by American hackers and explained here for the benefit of our overseas brethren, comes from the Warner Brothers' series of "Roadrunner" cartoons. In these cartoons, the famished Wile E. Coyote was forever attempting to catch up with, trap, and eat the Roadrunner. His attempts usually involved one or more high-technology Rube Goldberg devices -- rocket jetpacks, catapults, magnetic traps, high-powered slingshots, etc. These were usually delivered in large cardboard boxes, labeled prominently with the Acme name. These devices invariably malfunctioned in violent and improbable ways.

:acolyte: /n. obs./ [TMRC] An {OSU} privileged enough to submit data and programs to a member of the {priesthood}.

:ad-hockery: /ad-hok'*r-ee/ /n./ [Purdue] 1. Gratuitous assumptions made inside certain programs, esp. expert systems, which lead to the appearance of semi-intelligent behavior but are in fact entirely arbitrary. For example, fuzzy-matching of input tokens that might be typing errors against a symbol table can make it look as though a program knows how to spell. 2. Special-case code to cope with some awkward input that would otherwise cause a program to {choke}, presuming normal inputs are dealt with in some cleaner and more regular way. Also called `ad-hackery', `ad-hocity' (/ad-hos'*-tee/), `ad-crockery'. See also {ELIZA effect}.

:Ada:: /n./ A {{Pascal}}-descended language that has been made mandatory for Department of Defense software projects by the Pentagon. Hackers are nearly unanimous in observing that, technically, it is precisely what one might expect given that kind of endorsement by fiat; designed by committee, crockish, difficult to use, and overall a disastrous, multi-billion-dollar boondoggle (one common description is "The PL/I of the 1980s"). Hackers find Ada's exception-handling and inter-process communication features particularly hilarious. Ada Lovelace (the daughter of Lord Byron who became the world's first programmer while cooperating with Charles Babbage on the design of his mechanical computing engines in the mid-1800s) would almost certainly blanch at the use to which her name has latterly been put; the kindest thing that has been said about it is that there is probably a good small language screaming to get out from inside its vast, {elephantine} bulk.

:adger: /aj'r/ /vt./ [UCLA mutant of {nadger}, poss. from the middle name of an infamous {tenured graduate student}] To make a bonehead move with consequences that could have been foreseen with even slight mental effort. E.g., "He started removing files and promptly adgered the whole project". Compare {dumbass attack}.

:admin: /ad-min'/ /n./ Short for `administrator'; very commonly used in speech or on-line to refer to the systems person in charge on a computer. Common constructions on this include `sysadmin' and `site admin' (emphasizing the administrator's role as a site contact for email and news) or `newsadmin' (focusing specifically on news). Compare {postmaster}, {sysop}, {system mangler}.

:ADVENT: /ad'vent/ /n./ The prototypical computer adventure game, first designed by Will Crowther on the {PDP-10} in the mid-1970s as an attempt at computer-refereed fantasy gaming, and expanded into a puzzle-oriented game by Don Woods at Stanford in 1976. Now better known as Adventure, but the {{TOPS-10}} operating system permitted only six-letter filenames. See also {vadding}, {Zork}, and {Infocom}.

This game defined the terse, dryly humorous style since expected in text adventure games, and popularized several tag lines that have become fixtures of hacker-speak: "A huge green fierce snake bars the way!" "I see no X here" (for some noun X). "You are in a maze of twisty little passages, all alike." "You are in a little maze of twisty passages, all different." The `magic words' {xyzzy} and {plugh} also derive from this game.

Crowther, by the way, participated in the exploration of the Mammoth & Flint Ridge cave system; it actually has a `Colossal Cave' and a `Bedquilt' as in the game, and the `Y2' that also turns up is cavers' jargon for a map reference to a secondary entrance.

:AFAIK: // /n./ [Usenet] Abbrev. for "As Far As I Know".

:AFJ: // /n./ Written-only abbreviation for "April Fool's Joke". Elaborate April Fool's hoaxes are a long-established tradition on Usenet and Internet; see {kremvax} for an example. In fact, April Fool's Day is the only seasonal holiday consistently marked by customary observances on Internet and other hacker networks.

:AI: /A-I/ /n./ Abbreviation for `Artificial Intelligence', so common that the full form is almost never written or spoken among hackers.

:AI-complete: /A-I k*m-pleet'/ /adj./ [MIT, Stanford: by analogy with `NP-complete' (see {NP-})] Used to describe problems or subproblems in AI, to indicate that the solution presupposes a solution to the `strong AI problem' (that is, the synthesis of a human-level intelligence). A problem that is AI-complete is, in other words, just too hard.

Examples of AI-complete problems are `The Vision Problem' (building a system that can see as well as a human) and `The Natural Language Problem' (building a system that can understand and speak a natural language as well as a human). These may appear to be modular, but all attempts so far (1996) to solve them have foundered on the amount of context information and `intelligence' they seem to require. See also {gedanken}.

:AI koans: /A-I koh'anz/ /pl.n./ A series of pastiches of Zen teaching riddles created by Danny Hillis at the MIT AI Lab around various major figures of the Lab's culture (several are included under {AI Koans} in Appendix A). See also {ha ha only serious}, {mu}, and {{hacker humor}}.

:AIDS: /aydz/ /n./ Short for A* Infected Disk Syndrome (`A*' is a {glob} pattern that matches, but is not limited to, Apple or Amiga), this condition is quite often the result of practicing unsafe {SEX}. See {virus}, {worm}, {Trojan horse}, {virgin}.

:AIDX: /ayd'k*z/ /n./ Derogatory term for IBM's perverted version of Unix, AIX, especially for the AIX 3.? used in the IBM RS/6000 series (some hackers think it is funnier just to pronounce "AIX" as "aches"). A victim of the dreaded "hybridism" disease, this attempt to combine the two main currents of the Unix stream ({BSD} and {USG Unix}) became a {monstrosity} to haunt system administrators' dreams. For example, if new accounts are created while many users are logged on, the load average jumps quickly over 20 due to silly implementation of the user databases. For a quite similar disease, compare {HP-SUX}. Also, compare {Macintrash}, {Nominal Semidestructor}, {Open DeathTrap}, {ScumOS}, {sun-stools}.

:airplane rule: /n./ "Complexity increases the possibility of failure; a twin-engine airplane has twice as many engine problems as a single-engine airplane." By analogy, in both software and electronics, the rule that simplicity increases robustness. It is correspondingly argued that the right way to build reliable systems is to put all your eggs in one basket, after making sure that you've built a really good basket. See also {KISS Principle}.

:aliasing bug: /n./ A class of subtle programming errors that can arise in code that does dynamic allocation, esp. via `malloc(3)' or equivalent. If several pointers address (`aliases for') a given hunk of storage, it may happen that the storage is freed or reallocated (and thus moved) through one alias and then referenced through another, which may lead to subtle (and possibly intermittent) lossage depending on the state and the allocation history of the malloc {arena}. Avoidable by use of allocation strategies that never alias allocated core, or by use of higher-level languages, such as {LISP}, which employ a garbage collector (see {GC}). Also called a {stale pointer bug}. See also {precedence lossage}, {smash the stack}, {fandango on core}, {memory leak}, {memory smash}, {overrun screw}, {spam}.

Historical note: Though this term is nowadays associated with C programming, it was already in use in a very similar sense in the Algol-60 and FORTRAN communities in the 1960s.

:all-elbows: /adj./ [MS-DOS] Of a TSR (terminate-and-stay-resident) IBM PC program, such as the N pop-up calendar and calculator utilities that circulate on {BBS} systems: unsociable. Used to describe a program that rudely steals the resources that it needs without considering that other TSRs may also be resident. One particularly common form of rudeness is lock-up due to programs fighting over the keyboard interrupt. See {rude}, also {mess-dos}.