AOS

1. /aws/ (East Coast), /ay-os/ (West Coast) A

PDP-10 instruction that took any memory location 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.

2. /A-O-S/ or /A-os/ A Multics-derived operating system

supported at one time by Data General.

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 operators instead of postfixnotation.

[Jargon File]

(1995-11-26)