:AOS: 1. /aws/ (East Coast), /ay-os/ (West Coast) [based on a PDP-10 increment instruction] vt.,obs. To increase the amount of something. "AOS the campfire." Usage: considered silly, and now obsolete. Now largely supplanted by {bump}. See {SOS}. 2. A {{Multics}}-derived OS supported at one time by Data General. This was pronounced /A-O-S/ or /A-os/. A spoof of the standard AOS system administrator's manual (`How to Load and Generate your AOS System') was created, issued a part number, and circulated as photocopy folklore. It was called `How to Goad and Levitate your CHAOS System'. 3. Algebraic Operating System, in reference to those calculators which use infix instead of postfix (reverse Polish) notation.
Historical note: AOS in sense 1 was the name of a {PDP-10} instruction that took any memory location in the computer and added 1 to it; AOS meant `Add One and do not Skip'. Why, you may ask, does the `S' stand for `do not Skip' rather than for `Skip'? Ah, here was a beloved piece of PDP-10 folklore. There were eight such instructions: AOSE added 1 and then skipped the next instruction if the result was Equal to zero; AOSG added 1 and then skipped if the result was Greater than 0; AOSN added 1 and then skipped if the result was Not 0; AOSA added 1 and then skipped Always; and so on. Just plain AOS didn't say when to skip, so it never skipped.
For similar reasons, AOJ meant `Add One and do not Jump'. Even more bizarre, SKIP meant `do not SKIP'! If you wanted to skip the next instruction, you had to say `SKIPA'. Likewise, JUMP meant `do not JUMP'; the unconditional form was JUMPA. However, hackers never did this. By some quirk of the 10's design, the {JRST} (Jump and ReSTore flag with no flag specified) was actually faster and so was invariably used. Such were the perverse mysteries of assembler programming.
:app: /ap/ n. Short for `application program', as opposed to a systems program. What systems vendors are forever chasing developers to create for their environments so they can sell more boxes. Hackers tend not to think of the things they themselves run as apps; thus, in hacker parlance the term excludes compilers, program editors, games, and messaging systems, though a user would consider all those to be apps. Oppose {tool}, {operating system}.
:arc: [primarily MSDOS] vt. To create a compressed {archive} from a group of files using SEA ARC, PKWare PKARC, or a compatible program. Rapidly becoming obsolete as the ARC compression method is falling into disuse, having been replaced by newer compression techniques. See {tar and feather}, {zip}.
:arc wars: [primarily MSDOS] n. {holy wars} over which archiving program one should use. The first arc war was sparked when System Enhancement Associates (SEA) sued PKWare for copyright and trademark infringement on its ARC program. PKWare's PKARC outperformed ARC on both compression and speed while largely retaining compatibility (it introduced a new compression type that could be disabled for backward-compatibility). PKWare settled out of court to avoid enormous legal costs (both SEA and PKWare are small companies); as part of the settlement, the name of PKARC was changed to PKPAK. The public backlash against SEA for bringing suit helped to hasten the demise of ARC as a standard when PKWare and others introduced new, incompatible archivers with better compression algorithms.
:archive: n. 1. A collection of several files bundled into one file by a program such as `ar(1)', `tar(1)', `cpio(1)', or {arc} for shipment or archiving (sense 2). See also {tar and feather}. 2. A collection of files or archives (sense 1) made available from an `archive site' via {FTP} or an email server.
:arena: [UNIX] n. The area of memory attached to a process by `brk(2)' and `sbrk(2)' and used by `malloc(3)' as dynamic storage. So named from a semi-mythical `malloc: corrupt arena' message supposedly emitted when some early versions became terminally confused. See {overrun screw}, {aliasing bug}, {memory leak}, {memory smash}, {smash the stack}.
:arg: /arg/ n. Abbreviation for `argument' (to a function), used so often as to have become a new word (like `piano' from `pianoforte'). "The sine function takes 1 arg, but the arc-tangent function can take either 1 or 2 args." Compare {param}, {parm}, {var}.
:armor-plated: n. Syn. for {bulletproof}.