Glossary

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Core War has a vocabulary of its own. Anyone following the newsgroup or trying to decipher a ;strategy line needs these terms.

Briefly explained, with links to where they are covered in full.

A

A-field — The first operand of an instruction. In MOV.I $3, @7, $3 is the A-field. See Instruction set.

Addressing mode — The symbol in front of an operand (#, $, @, *, <, >, {, }). It determines how a value becomes an address. See Addressing modes.

Age — How many other people's submissions a warrior has survived on a displacement hill. The criterion for the Hall of Fame: 100 on the 94nop hill. See Hills and community.

;assert — Header line that makes assembly fail if the environment does not match — for instance ;assert CORESIZE == 8000.

B

B-field — The second operand of an instruction. Frequently repurposed by instructions as pointer storage.

Bomb — An instruction a warrior writes into foreign territory to kill processes there. Classically DAT, but also SPL or JMP depending on intent.

Boot (bootstrapping) — A warrior copies itself elsewhere in the core before the real fight and continues there. That decouples it from its load position — if the opponent finds the old location, it hits nothing.

C

Cell — A memory location in the core. Always holds exactly one complete instruction — data and program are the same thing.

Clear (core clear) — Systematic overwriting of memory without aiming. Usually the endgame of an attack. See Strategy encyclopaedia.

CMP — Old name for SEQ. Both spellings are permitted.

Core — The memory in which the fight takes place. A ring of (usually) 8000 cells. Before a round starts it is filled throughout with DAT.F $0, $0 — that is, lethal everywhere.

Core size — The number of cells in the core. All address arithmetic is modulo this value.

Cycle — One unit of execution. Per cycle each living warrior executes exactly one instruction. After 80,000 cycles without a decision, the round ends in a tie.

D

DAT — The only instruction that kills: a process running onto it terminates. Also the fill value of empty core.

Decoy — Filler intended to occupy a scanner. Because it differs from empty core, a scanner takes it for a find and wastes its attack.

DJN stream — An attack technique that uses DJN to continuously decrement values in foreign cells, rendering them useless without overwriting them.

E

EQU — Defines a named constant at assembly time. step EQU 4 makes step mean four everywhere.

Evolver — A program that produces warriors by mutation and selection rather than writing them. See Tools and engines.

G

Gate — A defensive cell that catches passing imps. Anyone hoping to survive imp rings needs one.

H

Hall of Fame — A distinction on corewar.co.uk that cannot be applied for; it follows a warrior's age alone.

Hill — A continuous public ranking on which every new warrior faces all the existing ones. Two designs: displacement hill (fixed size, the last one drops off) and unlimited hill (everyone stays). See Hills and community.

Hybrid — A warrior combining two strategy classes, for example paper with stone. That is the norm at the top today; pure forms are teaching models.

I

ICWS — International Core Wars Society. Publisher of the ICWS'88 standard and the '94 draft. See Standards.

Imp — A warrior that copies itself forward and runs after the copy: MOV.I $0, $1. Cannot win, but is hard to kill.

Imp ring / imp spiral — Several imps distributed evenly across the core that repair each other. Considerably more robust than a single imp.

K

Koenigstuhl — The unlimited hill run by Christoph C. Birk, with over 1100 warriors spanning three decades. The basis of every measurement in this reference.

KOTH — King of the hill. Both the game principle and the name of the oldest server (koth.org).

M

MARS — Memory Array Redcode Simulator. The collective term for Core War simulators.

Modifier — The suffix after the dot (.A, .B, .AB, .BA, .F, .X, .I). It determines which fields an instruction touches — and thereby the meaning more than the opcode does. See Modifiers.

N

Nano — A rule set with a very small core and very short warriors. An ecosystem of its own, where different strategies work.

;name — Header line with the warrior's name. It appears that way in the ranking.

O

Oneshot — A warrior that scans once thoroughly and stakes everything on that one hit. See Strategy encyclopaedia.

Opcode — The actual instruction, such as MOV or SPL. There are 16.

Optimiser — A program that searches for better constants for an existing warrior without changing its structure.

P

Paper — Replicator: reproduces faster than the opponent can destroy. See Strategy encyclopaedia.

pMARS — The portable reference simulator. In case of doubt, its behaviour is the authoritative reading of the standard.

Process — One thread of execution of a warrior. Important: more processes do not make you faster — a warrior executes exactly one instruction per cycle and the processes share the time. Processes are robustness, not speed.

P-space — Private memory that survives a round. Lets a warrior learn from lost rounds. Disabled under '94nop.

Q

Quickscanner (qscan) — Not a warrior of its own but an opening: a few widely spaced probe points in the first cycles. If it hits, the battle is decided before the opponent runs. Hence the notation qscan -> something in many strategy notes.

R

Redcode — The assembly language of Core War.

;redcode-<hill> — Must be on line 1 of a submission and determines the target hill, for example ;redcode-94nop.

Replicator — See paper.

Round — A single battle. A test run consists of many rounds with freshly randomised load positions.

S

SAL — Survival Analysis Lab, operator of several hills including the beginner hill.

Scanner — A warrior that searches the core for deviations from the empty state and strikes precisely. See Strategy encyclopaedia.

Score — The rating on a hill: (wins × 3 + ties) × 100 / rounds. An average against the current field — it changes without you doing anything.

Silk — The most widespread paper construction. Starts the new process at the target address before the copy is finished, and thereby reproduces in parallel.

SPL — The instruction that creates an additional process. The basis of every replicator. See Instruction set.

Stone — Bomber: blindly scatters DAT bombs at regular intervals. See Strategy encyclopaedia.

;strategy — Header line in which the author briefly describes what the warrior does. Also the usual place for attribution.

T

;test — Server command that only assembles a warrior without submitting it. Sensible on a first attempt.

Tie — Both warriors are still alive when the cycles run out. Not a fallback result but a tool: a tie is worth a third of a win, and some top warriors are deliberately built around them.

Tiny — A rule set with a small core and short warriors, between nano and the standard format.

V

Vampire — A warrior that redirects enemy processes into a pit instead of killing them. Structurally hopeless against floods of processes. See Strategy encyclopaedia.

W

Warrior — A Core War program.

Wipe — Area overwriting of a region, usually after a scan hit.

Related pages

• Instruction set · Addressing modes · Modifiers · Standards
• Strategy encyclopaedia · Tools and engines · Hills and community

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