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 postfix notation.
[Jargon File]
(1995-11-26)
Nearby terms:
AOCE « AOL « AOP « AOS » APA » Apache »
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