Nathan-R-Og/dq2

Cite as: Nathan-R-Og/dq2
Original: https://github.com/Nathan-R-Og/dq2
Pinned: Nathan-R-Og/dq2 @ 0fb64a46310ec2c144f72c92cb640e4ec9e7691a
Accessed: 2026-10-21
Licence: none stated (no LICENSE file)
Credit: Nathan-R-Og, who turned the disassembly into ca65 source that rebuilds the ROM; the README says it is "based off of the dissassembly found" on Data Crystal (Dragon Warrior II (NES)/ROM map/ASM), and the bank files carry that page's comments. Every label and comment quoted in dw2 claims comes from this repo.
Notes: ca65 source for Dragon Warrior II (USA); the README lists the NES 2.0 dump's MD5, 3188792f0e6baee937a9859542c8c155, which is the atlas's ROM (dragon-warrior-ii-nes-rom). Built with cc65 (commit 8d86ca7e) on 2026-10-21, it reproduced that ROM byte for byte. Bank 4 (battle, encounters) and the fixed bank (constant.asm) assemble from source; only some graphics and bank 5 come from the ROM at build time.

Cited on

Claims (11)

In Dragon Warrior II (the North American NES release), each step draws a random byte from 1 to 255 and starts a fight when the terrain's rate is at least that byte: on the world map 10 on grass, 16 in forest, desert, and swamp, 25 on mountains, and 4 at sea; 8 on maps numbered $2B and up and in Moonbrooke, while the other maps below $2B have none.	`src/us/prg/bank4.asm L54–58src/us/prg/bank4.asm L62–69src/us/prg/bank4.asm L159–163src/us/prg/bank4.asm L648–656`	Code
In Dragon Warrior II (NA NES), a hero's attack takes $X = A - ⌊ D / 2 ⌋$ , attack power less half the monster's defense; if $X$ is under 2 the hit deals 0 or 1, and otherwise $⌊ X r / 256 ⌋$ , where $r$ is 8 plus the sum of sixteen random 0–15 rolls (8 to 248, centered on 128), so about half of $X$ ; a hero under Surround deals 0 one time in 4.	`src/us/prg/bank4.asm L6284–6290src/us/prg/bank4.asm L9138–9142src/us/prg/bank4.asm L5098–5126src/us/prg/bank4.asm L6299–6309src/us/prg/bank4.asm L3025src/us/prg/bank4.asm L5214–5240`	Code
In Dragon Warrior II (NA NES), a hero's attack is "a tremendous blow" on a roll of 1 in 64, or 1 in 8 with the Sword of Destruction equipped, except against Malroth; with the Sword of Destruction (or Gremlin's Armor or the Evil Shield) a roll of 1 in 4 first freezes the hero under the curse and the attack is lost. A tremendous blow deals half the attack power plus $⌊ A r / 256 ⌋$ with the same 8–248 roll, ignores defense, and skips the monster's dodge.	`src/us/prg/bank4.asm L6241–6282src/us/prg/bank4.asm L6334–6335src/us/prg/bank4.asm L2926src/us/prg/bank4.asm L6529–6542src/us/prg/bank4.asm L5244–5279`	Code
In Dragon Warrior II (NA NES), after a hero's normal hit is rolled, a monster that isn't asleep dodges when a roll of 0–63 falls below the high nibble of its second stat byte, which the disassembly calls its "evade chance / 64"; heroes dodge a monster's attack 1 time in 64, and the Clothes Hiding adds a second chance of 1 in 8.	`src/us/prg/bank4.asm L6310–6329src/us/prg/bank4.asm L5079src/us/prg/bank4.asm L6180–6199src/us/prg/bank4.asm L6935–6958src/us/prg/bank4.asm L8011–8015`	Code
In Dragon Warrior II (NA NES), each round every living hero and monster gets a key of half its agility, rounded down, plus a random byte plus a random 0 or 1, capped at 255, and a selection sort sets the order from the highest key down.	`src/us/prg/bank4.asm L9168–9210src/us/prg/bank4.asm L4814–4823src/us/prg/constant.asm L732–760src/us/prg/bank4.asm L9235–9250src/us/prg/bank4.asm L9274–9286`	Code
In Dragon Warrior II (NA NES), a battle opens with a roll of 0–31: on 0 the monsters "did not see" the party and lose their first round, and on 1 they attack "before [the hero] was set for battle" and the heroes lose theirs.	`src/us/prg/bank4.asm L3120–3146src/us/prg/bank4.asm L3241–3258src/us/prg/bank4.asm L3298–3299`	Code
In Dragon Warrior II (NA NES), the party runs when the first hero chooses to; it never escapes a boss (monster $4E and up) or one fixed fight in the Sea Cave, always escapes in the round the monsters "did not see" it, and otherwise fails 1 time in 3.	`src/us/prg/bank4.asm L3152–3200`	Code
In Dragon Warrior II (NA NES), as in Dragon Warrior, each monster starts a fight with its base HP less up to a quarter; the order changes, as Dragon Warrior II quarters the base HP before multiplying by a random byte, $H - ⌊ ⌊ H / 4 ⌋ r / 256 ⌋$ , where Dragon Warrior quarters the product.	`src/us/prg/bank4.asm L9138–9162`	Code
Dragon Warrior II (NA NES) changes Dragon Warrior's battle rules: the hero's 1-in-32 "excellent move" becomes a 1-in-64 "tremendous blow", the fixed alternation of hero and monster becomes a round order sorted by half the agility plus a roll, and running no longer weighs the hero's Agility against the monster.	`src/us/prg/bank4.asm L6249–6250src/us/prg/bank4.asm L9274–9286src/us/prg/bank4.asm L3191–3197`	Code
Dragon Warrior III (NA NES) keeps Dragon Warrior II's critical-hit odds for most heroes, 1 in 64, and its 1 in 8 with the Sword of Destruction.	`src/us/prg/bank4.asm L6241–6250`	Code
Dragon Warrior III (NA NES) changes Dragon Warrior II's round order: Dragon Warrior II adds a random byte (and a random 0 or 1) to half the agility, while Dragon Warrior III scales the agility itself by a random factor from a quarter to one.	`src/us/prg/bank4.asm L9274–9283`	Code