AOS

AOS 1. /aws/ (East Coast), /ay-os/ (West Coast)
   vt.,obs.  To increase the amount of something.  "AOS the
   campfire."  [based on a PDP-10 increment instruction] Usage:
   considered silly, and now obsolete.  Now largely supplanted by
   {bump}.  See {SOS}.  2. n. 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. n. Algebraic Operating System, in reference
   to those calculators which use infix instead of postfix (reverse
   Polish) notation.  4. A {BSD}-like operating system for the IBM
   RT.

   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.