The Legend of Zelda: A Link to the Past (kan's US disassembly)

A monster's bump damage class (0–9) and Link's mail (green, blue, or red) pick the damage of a touch from a 10 × 3 table, in eighths of a heart. Class 3 takes 8, 4, or 2; class 9 takes 64, 48, or 24; class 1 takes 4 whatever the mail. alttp/bump-damage

About: The Legend of Zelda: A Link to the Past Damage formula

{
 "class0": [
  2,
  1,
  1
 ],
 "class1": [
  4,
  4,
  4
 ],
 "class2": [
  0,
  0,
  0
 ],
 "class3": [
  8,
  4,
  2
 ],
 "class4": [
  8,
  8,
  8
 ],
 "class5": [
  16,
  8,
  4
 ],
 "class6": [
  32,
  16,
  8
 ],
 "class7": [
  32,
  24,
  16
 ],
 "class8": [
  24,
  16,
  8
 ],
 "class9": [
  64,
  48,
  24
 ]
}

A heart is 8 units (heart-container). LinkControlHandler subtracts the pending damage from the life byte $7EF36D (bank_07.asm L158-L166).

Cited by: The Legend of Zelda: A Link to the Past

A monster's touch does nothing while Link's blink timer is above 0. A hit sets it to 58, and Link's sprite routine counts it down once a frame, so the protection lasts 58 frames. alttp/hurt-iframes

About: The Legend of Zelda: A Link to the Past Invincibility frames

Value: 58 frames

The same routine then hides Link on even values of 4 and above (L4539-L4543), the blink.

Cited by: The Legend of Zelda: A Link to the Past

A monster's touch sets Link's speed to 24 on the longer axis of the line from the monster to Link, the other axis in proportion, with a hop of vertical speed 12. It also sets a timer to 19 and Link's recoil flag. While the flag is set, his state handler runs the recoil state instead of the code that reads the buttons, and that state counts the timer down each frame, holding it at 1 until Link lands, so the recoil lasts at least 19 frames. alttp/recoil

About: The Legend of Zelda: A Link to the Past Knockback

{
 "speed": 24,
 "hop": 12,
 "frames": 19
}

The vector is the one sprites use to move toward Link, so applied to Link it carries him away from the monster. How the recoil state moves him each frame (HandleLinkRecoilVelocity) wasn't read, so whether the speed holds isn't shown.

Cited by: The Legend of Zelda: A Link to the Past

Each Piece of Heart adds 1 to a count kept modulo 4; the piece that brings it back to 0 grants item $26, a heart container. alttp/heart-pieces

About: The Legend of Zelda: A Link to the Past Health upgrade

Value: 4

Cited by: Health upgrade, The Legend of Zelda: A Link to the Past

A heart container adds 8 to Link's life capacity, one heart, up to $A0, 20 hearts. The one from four pieces refills his life to the new capacity; the one a boss leaves adds a single heart of life. alttp/heart-container

About: The Legend of Zelda: A Link to the Past Health upgrade

{
 "perContainer": 8,
 "max": 160
}

Item $3F, the Sanctuary's container, refills like the one from four pieces.

Cited by: Health upgrade, The Legend of Zelda: A Link to the Past

A Link to the Past fires the sword beam only with the Master Sword or better and less than half a heart missing; The Legend of Zelda fired it with up to half a heart missing and any sword. alttp/sword-beam

About: The Legend of Zelda: A Link to the Past Sword beam

The check between (L5901-L5904) also turns away a sword byte of $FF. Only one beam flies at a time (L5912-L5920).

Cited by: Sword beam, The Legend of Zelda: A Link to the Past

Each magic item's cost comes from a table with three columns, and one byte, $7EF37B, picks the column for every item. The rods cost 16, 8, or 4; the medallions 32, 16, or 8; the powder 8, 4, or 2; the lamp 4, 2, or 2. alttp/magic-costs

About: The Legend of Zelda: A Link to the Past Magic meter

{
 "rod": [
  16,
  8,
  4
 ],
 "medallion": [
  32,
  16,
  8
 ],
 "powder": [
  8,
  4,
  2
 ],
 "lamp": [
  4,
  2,
  2
 ],
 "byrna": [
  16,
  8,
  4
 ]
}

The labels rod, medallion, powder, lamp, and byrna are the disassembly's.

Cited by: Magic meter, The Legend of Zelda: A Link to the Past

A defeated monster's prize pack (1–7) gives a drop half the time, and pack 4 always. Each pack keeps its own counter that steps through 8 prizes in order; pack 1's row is heart, heart, heart, heart, green rupee, heart, heart, green rupee. alttp/prize-packs

About: The Legend of Zelda: A Link to the Past Item drop table

{
 "packs": 7,
 "cycle": 8,
 "rarityMask": [
  1,
  1,
  1,
  0,
  1,
  1,
  1
 ]
}

A luck setting ($0CF9) overrides the chance until 10 kills (L24115-L24130), and some monsters force a key or rupee drop (L24085-L24103); neither was followed further.

Cited by: Item drop table, The Legend of Zelda: A Link to the Past, The Legend of Zelda: Oracle of Seasons and Oracle of Ages

Each dungeon keeps its own small-key count. Loading a dungeon copies its count from a per-dungeon array into the current count, SaveDungeonKeys copies it back, and the overworld sets the current count to $FF. The Sewers and Hyrule Castle share one slot. alttp/dungeon-keys

About: The Legend of Zelda: A Link to the Past Keys and locked doors

The load is in Module06_UnderworldLoad, which passes the count to RebuildHUD_Keys to store; the save in SaveDungeonKeys, and the $FF in Module08_OverworldLoad. The per-dungeon tables list the Sewers as dungeon 0 and Hyrule Castle as dungeon 2, two bytes apart.

Cited by: Keys and locked doors, The Legend of Zelda: A Link to the Past