The Legend of Zelda

On this page

Hearts and damage
Invincibility after a hit
The shove
Hitting monsters
Item drops
Health growth
Related
Mechanics
References
Sources

The Legend of Zelda is Nintendo’s 1986 action-adventure; its NES release reached North America in August 1987¹. Aldo Núñez’s disassembly labels and comments the whole US release. He built it from the first revision, PRG0. The ROM measured here is Rev 1, and its combat and drop code is byte-identical to his source².

#Hearts and damage

Link’s health is a count of full hearts plus a partial heart, a byte from $00 to $FF; a new file starts with 3 hearts^3,3. A monster’s contact damage comes from a table with one byte per object type. Half a heart is the most common entry, and Ganon’s four hearts tie for the largest^4,5. Each level of ring halves the damage before it is subtracted⁶.

When the partial heart can’t cover a hit, the game takes a full heart and refills the partial heart to $FF rather than $100. Each such borrow costs an extra 1/256 of a heart⁷. In the probe, five half-heart hits from three hearts leave a partial heart of $7D, not $80⁸.

#Invincibility after a hit

A hit sets Link’s invincibility timer to 24 and his shove distance to 32 px, and no monster can touch him while the timer is above 0⁹. The timer drops by 1 only on even frames, so 24 lasts 48 frames¹⁰. The comment beside it reads “Mark Link invincible $18 frames”, counting timer steps as frames⁹.

The probe holds a Tektite against Link from power-on. It hurts him every 47 or 48 frames⁸, depending on whether the hit falls on an odd or even frame⁸. The timer reaches 0 before the monsters’ contact checks run, so a monster still touching Link hurts him on that same frame⁸.

While Link holds the clock, the game adds 16 to the timer every frame, and monsters’ contact checks return no collision¹¹.

#The shove

A shove moves Link 4 px/frame¹², one pixel of shove distance at a time¹². It points away from the monster¹³. It stops early at the room’s edge, or at an unwalkable tile when Link is aligned to the grid¹². While it lasts, it replaces his walking, so the player can’t steer¹⁴. The monster then turns around, unless it is a Vire or carries the attribute bit that the disassembly’s comments call “reverse after hit Link”¹³.

In the probe, three hits shove Link 32 px in 8 frames¹⁵ each. The fourth hit lands 8 px from the room’s edge, and the shove covers only those 8 px¹⁵.

#Hitting monsters

The wooden, white, and magical swords take $10, $20, and $40 from a monster’s hit points. Fire takes $10 and a bomb $40; the boomerang only stuns¹⁶. A monster that a weapon hurts gets the same treatment as Link with different numbers. Its timer is set to 16, which lasts 32 frames, and it is shoved 64 px in the weapon’s direction¹⁷. A monster immune to the weapon’s damage type is neither hurt nor shoved¹⁷.

#Item drops

When a monster dies, SetUpDroppedItem chooses its drop by a table, a counter, and a chance^18,19,20. The monster’s type puts it in one of four groups; seven types, among them the Gels, the Keese, and the Like Like, never drop anything¹⁸. Every kill advances a kill cycle from 0 to 9 and back, before the drop is chosen²¹. Three types don’t advance it, among them the ones the comments call Child Gel and Red Keese²¹.

The group picks a row of the table and the kill cycle its column¹⁹. The drop then happens only when the monster’s slot’s byte of Random is below the group’s rate²⁰:

Group	Types	Rate	Row, columns 0–9
A	`$07` `$08` Octoroks, `$0E` Tektite, `$04` Moblin, `$0F` Leever, `$23` Wizzrobe^18,5	80 in 256²⁰	heart, rupee, heart, rupee, fairy, rupee, heart, heart, rupee, rupee¹⁹
B	`$21` `$22` Ghinis, `$0D` Tektite, `$10` Leever, `$13` Zol, `$28` Rope, `$2A` Stalfos, `$27` Wallmaster, `$16` Pols Voice^18,5	152 in 256²⁰	5 rupees, rupee, heart, rupee, 5 rupees, heart, clock, rupee, rupee, rupee¹⁹
C	`$09` `$0A` Octoroks, `$03` Moblin, `$01` Lynel, `$12` Vire, `$06` Goriya, `$0B` Darknut, `$24` Wizzrobe, `$30` Gibdo^18,5	104 in 256²⁰	heart, bombs, rupee, clock, rupee, heart, bombs, rupee, bombs, heart¹⁹
D	every other type that drops, such as `$05` Goriya and `$0C` Darknut^18,5	104 in 256²⁰	heart, heart, fairy, rupee, heart, fairy, heart, heart, heart, rupee¹⁹

Two counters override the table. Both count kills since Link was last hurt, and a hit zeroes them²². The 16th such kill drops a fairy, if the monster can drop at all²³. The 10th drops 5 rupees, or bombs when the 10th kill was by bomb, and its count starts again²⁴. A fairy restores 3 hearts and a heart 1²⁵. A dropped item lasts about 510 frames, and Link can’t take it for the first 30 or so²⁶.

The probe calls the game’s own routine for every group, kill-cycle column, and random byte. It drops in 800, 1,520, 1,040, and 1,040 of 2,560²⁷ cases for groups A to D, each time the item in its column²⁷. The Speed Demos Archive Knowledge Base gives the same 10th-kill and 16th-kill rules²⁸.

on a kill (the death sparkle has ended):
    kill_cycle = (kill_cycle + 1) mod 10      # not for split Gels and Keese
    if type never drops: done
    item = TABLE[group][kill_cycle]
    if kills_since_hurt == 16:  item = fairy; help_count = 0
    elif help_count >= 10:      item = bombs if the 10th was by bomb else 5 rupees; help_count = 0
    elif Random[slot] >= RATE[group]: no drop

#Health growth

A heart container adds a container and a full heart, up to 16 containers²⁹. A new file has three³.

Mechanics

Mechanic	Kind	How
Status bar split	Sprite 0 hit	waits for sprite 0 under the map and item bar; scrolls vertically between rooms by rewriting PPUADDR mid-frame
Raster effects	Two bands	a PPUADDR rewrite at the split gives the room below its own vertical position
Music driver	Length table	Super Mario Bros.' layout: per-song length rows, big-endian periods
DPCM samples	Sound effects	7 samples for boss roars, a boss hit, and a hurt sound
Invincibility frames	Slow timer	24 on a timer that counts down every other frame
Knockback	Fixed shove	a fixed 32 px shove at 4 px per frame
Item drop table	Kill cycle	four groups, a 10-step kill cycle, and streak bonuses
Damage formula	Fixed table	a damage byte per monster type, halved per ring
Health upgrade	Whole containers	heart containers only, three to sixteen
Sword beam	Near full	any sword, with up to half a heart missing
Keys and locked doors	One count	one key per locked door, or none with the magic key
Password and battery save	Battery save with copies	three files with a 16-bit sum and marker bytes; each save goes to a scratch copy first

Every claim about this game, by concept (39)

general	Wikidata lists Nintendo and Nintendo Entertainment Analysis & Development as the developers of The Legend of Zelda and Nintendo as its publisher; it dates the game 21 February 1986, with no place or platform, and its NES release in North America 22 August 1987.	Wikidata
	The PRG0 source of aldonunez's disassembly differs from Rev 1 in the music engine, in bank 5's continue screen and room code, which Rev 1 moves, in bank 7's calls into that code, and in the header checksum; the combat code in banks 1 and 7 and the drop code in bank 4 are byte-identical.	Code
	An object's type indexes `UpdateObject_JumpTable`, whose routines name the monsters: Lynel `$01`, Moblin `$03`–`$04`, Goriya `$05`–`$06`, Octorok `$07`–`$0A`, Darknut `$0B`–`$0C`, Tektite `$0D`–`$0E`, Leever `$0F`–`$10`, Vire `$12`, Zol `$13`, Gel `$14`–`$15`, Pols Voice `$16`, Like Like `$17`, Keese `$1B`–`$1D`, Ghini `$21`–`$22`, Wizzrobe `$23`–`$24`, Wallmaster `$27`, Rope `$28`, Stalfos `$2A`, Gibdo `$30`, and Ganon `$3E`.	Code
Damage formula	Link's health is `HeartValues`, whose high nibble is the heart containers less one and whose low nibble is the full hearts, plus a partial heart in `HeartPartial` from `$00` to `$FF`; a new file starts at `$22` and `$FF`, three containers and three hearts.	Code
	A monster's contact damage comes from `ObjTypeToDamagePoints`, one byte per object type, whose low nibble is whole hearts and whose high nibble is sixteenths of a heart; of its 93 entries, 30 are half a heart, 24 one heart, 18 two hearts, and 3 four hearts.	Code
	Each level of ring halves the damage before it is subtracted, so the first ring takes half and the second a quarter.	Code
	When the partial heart can't cover the damage, the game takes a full heart and refills the partial heart to `$FF` rather than `$100`, so each such borrow costs Link an extra 1/256 of a heart.	Code
	The wooden, white, and magical swords take `$10`, `$20`, and `$40` from a monster's hit points; fire takes `$10`, a bomb `$40`, and the boomerang none, only stunning.	Code
Destructible terrain	The NES Legend of Zelda booklet describes the bomb only as a weapon, a blast against enemies (p. 13); of the invisible doors in caves it says only "That's a secret".	Manual
DPCM samples	The game keeps 7 DMC samples in three tables of address, length, and rate bytes, and a request byte picks the entry by its lowest set bit.	Code
DPCM samples	The samples are sound effects; boss code requests `$10` for the Aquamentus, Gleeok, and Ganon roar (entry 4, rate `$0E`), `$20` for the Dodongo and Gohma roar (entry 5), and `$02` for a boss hit (entry 1), and `DeleteSlot` requests `$08`, which the disassembly labels the "hurt" sound (entry 3).	Code
Health upgrade	A heart container adds one container and one full heart, up to 16 containers; a new file starts with three.	Code
Invincibility frames	A monster that touches Link while his invincibility timer is above 0 does nothing; a hit sets the timer to 24 and his shove distance to 32 px.	Code
	`DecrementInvincibilityTimer` lowers an object's invincibility timer by 1 only on frames when `FrameCounter` is even, so a timer of $t$ lasts $2 t$ frames.	Code
	While Link holds the clock, `BeginUpdateWorld` adds 16 to his invincibility timer every frame, and monsters' contact checks return no collision.	Code
	Measured in Rev 1, a Tektite held against Link hurts him every 47 or 48 frames, taking half a heart each time; from three hearts, five hits leave `$20` and `$7D`, 3/256 of a heart under a half heart.	Verified
	A weapon that hurts a monster sets the monster's invincibility timer to 16, which lasts 32 frames, and shoves it 64 px in the weapon's direction, unless the monster is already invincible or immune to the weapon's damage type.	Code
Item drop table	Whenever Link is hurt, the game zeroes `WorldKillCount`, `HelpDropCount`, and `HelpDropValue`, the counters behind the fairy and the 10th-kill drops.	Code
	`SetUpDroppedItem` sorts a dead monster's type into one of four drop groups by three type lists, with every unlisted type in the fourth; seven types, among them the Gels, the Keese, and the Like Like, drop nothing.	Code
	`DropItemTable` holds ten items for each group, and the kill cycle picks the column; group A's row is heart, rupee, heart, rupee, fairy, rupee, heart, heart, rupee, rupee.	Code
	In `TakeItem`, item `$18` is a rupee, `$0F` five rupees, `$22` a heart, `$23` a fairy, `$21` the clock, and `$00` four bombs; a heart restores 1 heart and a fairy 3.	Code
	Outside the special cases, a drop happens only when the dead monster's slot's byte of `Random` is below its group's rate: `$50`, `$98`, `$68`, and `$68`, or 80, 152, 104, and 104 in 256.	Code
	Each kill advances `WorldKillCycle` from 0 to 9 and back to 0 before the drop is chosen, except kills of types `$5D`, `$14`, and `$1C`, which the comments call a Child Gel and a Red Keese.	Code
	When `WorldKillCount`, the kills since Link was last hurt, equals 16 and the monster can drop items, the drop is a fairy, whatever its random byte.	Code
	The 10th kill since Link was last hurt brings a guaranteed drop of 5 rupees, or of bombs when that 10th kill was by bomb, and the count starts again from 0.	Code
	A dropped item lasts 255 decrements of its lifetime, one every other frame, about 510 frames, and Link can't take it until the 16th decrement, about 32 frames.	Code
	Called in Rev 1 for every group, kill-cycle column, and value of the random byte, `SetUpDroppedItem` drops in 800, 1,520, 1,040, and 1,040 of 2,560 cases for groups A to D, each the item its column names; it gives a fairy at a kill count of 16, and 5 rupees or bombs at a help count of 10.	Verified
	The Speed Demos Archive Knowledge Base states that 10 kills without being hit force a 5-rupee drop, or a bomb when the 10th is killed by bomb, and that 16 kills in a row force a fairy, only when the 16th enemy can drop items.	Wiki
Keys and locked doors	Touching a locked door with the magic key opens it for free; otherwise it costs a key, and with no keys the door blocks Link.	Code
Knockback	A shoved object moves 4 px a frame, 1 px of shove distance at a time, and the shove ends early when the object reaches the room's edge or, aligned to the grid, an unwalkable tile.	Code
	`Walker_Move` moves a walking object by its shove whenever one is set, in place of its walking, so Link can't steer during a shove.	Code
	When a monster hits Link, the shove points away from the monster along one axis: the horizontal one when Link is between grid squares and faces left or right, the vertical one when he is between squares facing up or down. The monster then turns around, unless bit 7 of its object attributes is set (a flag the disassembly's comments name "reverse after hit Link") or it is a Vire (object type `$12`).	Code
	Measured in Rev 1, each of the Tektite's first three hits shoves Link 32 px to the right in 8 frames.	Verified
Music driver	The music driver has Super Mario Bros.' layout; a song entry sets a base into a note-length table, a length code's low 3 bits index it, notes index a table of big-endian 16-bit timer periods, and a square note starts with duty byte `$82` and sweep byte `$7F`, the same register values Super Mario Bros. uses.	Code
Password and battery save	The Legend of Zelda keeps three save files in battery-backed cartridge RAM; each holds an 8-byte name, a 40-byte item block, 384 bytes of world flags, and four single bytes (whether the slot is in use, one unlabeled byte, the death count, and the quest), with a 16-bit checksum that is the plain sum of those 436 bytes, and, kept apart and outside the sum, two marker bytes, $5A and $A5.	Code
	The Legend of Zelda saves in two steps; it first writes the whole file to a second copy, file B, sums it, stores that sum, and marks B uncommitted, and on the next step it sums B again and, if the sums agree, clears file A's markers, copies B over A, writes A's markers and sum, and marks B committed.	Code
	When its title demo or its file select screen starts, The Legend of Zelda checks each of the three slots; a file B still marked uncommitted whose sum matches is copied over file A, finishing a save that was cut off, and a file A whose markers are not $5A and $A5 or whose sum doesn't match is formatted, its name set to spaces and every other byte to 0.	Code
Status bar split	When a mode needs the split, the NMI handler waits for the sprite 0 hit under the status bar and then sets the scroll for the room below; while the screen scrolls vertically between rooms it rewrites `PPUADDR` (`$2006`) mid-frame instead of `PPUSCROLL`.	Code
Sword beam	`MakeSwordShot` fires a sword beam only when the low nibble of `HeartValues` (full hearts) equals its high nibble, as it does when Link's hearts are full, and the partial heart is at least `$80` of `$FF`, so with up to half a heart missing; unless `ForceSwordShot` (`$0529`) is set.	Code

References

^Wikidata lists Nintendo and Nintendo Entertainment Analysis & Development as the developers of The Legend of Zelda and Nintendo as its publisher; it dates the game 21 February 1986, with no place or platform, and its NES release in North America 22 August 1987.WikidataWikidata
How we know
+1986-02-21T00:00:00Z … +1987-11-15T00:00:00Z … +1987-08-22T00:00:00Z
Q12395, P178 developer, P123 publisher, and P577 publication date qualified by P291 place and P400 platform · archived copy ↗
The quote matches our archived copy.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^The PRG0 source of aldonunez's disassembly differs from Rev 1 in the music engine, in bank 5's continue screen and room code, which Rev 1 moves, in bank 7's calls into that code, and in the header checksum; the combat code in banks 1 and 7 and the drop code in bank 4 are byte-identical.Code“Legend of Zelda, The (USA) (Rev 1)” · aldonunez/zelda1-disassembly
How we know
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1 BeginShove, run from RAM at $7E26, one of the routines identical in both. We don't reproduce the bytes.
```
6016; Unknown block
6017    .BYTE $5A, $45, $4C, $44, $41, $D7, $C8, $00
6018    .BYTE $00, $38, $04, $01, $04, $01, $BE
```
src/Z_07.asm lines 6016–6018 at 50a1c86 · upstream ↗
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^ a b cLink's health is HeartValues, whose high nibble is the heart containers less one and whose low nibble is the full hearts, plus a partial heart in HeartPartial from $00 to $FF; a new file starts at $22 and $FF, three containers and three hearts.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
1667    ; Initialize file B hearts value to 3 heart containers and 2 hearts.
1668    LDY #$18
1669    LDA #$22
1670    STA ($C0), Y
1671    INY                         ; Initialize file B heart partial to full.
1672    LDA #$FF
```
src/Z_02.asm lines 1667–1672 at 50a1c86 · upstream ↗
```
4681CompareHeartsToContainers:
4682    LDA HeartValues
⋮
4684    AND #$0F
⋮
4687    LSR
4688    LSR
4689    LSR
4690    LSR
4691    CMP $00
```
src/Z_01.asm lines 4681–4691 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 2 $9EF0, UpdateModeERegister, which writes the new file. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^A monster's contact damage comes from ObjTypeToDamagePoints, one byte per object type, whose low nibble is whole hearts and whose high nibble is sixteenths of a heart; of its 93 entries, 30 are half a heart, 24 one heart, 18 two hearts, and 3 four hearts.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
5574ObjTypeToDamagePoints:
5575    .BYTE $60, $02, $01, $80, $80, $01, $80, $80
5576    .BYTE $80, $80, $80, $01, $02, $80, $80, $01
```
src/Z_01.asm lines 5574–5586 at 50a1c86 · upstream ↗
```
5725    ; Unpack the damage points for the monster's type.
5726    ; The low nibble is the high byte.
5727    ; (Damage points byte AND $F0) is the low byte.
5728    LDY ObjType, X
5729    LDA ObjTypeToDamagePoints, Y
5730    PHA
5731    AND #$0F
5732    STA $0D
5733    PLA
5734    AND #$F0
5735    STA $0E
```
src/Z_01.asm lines 5725–5735 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1, the table, run from RAM at $7A4A. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-25.
Checked by a second AI model, 2026-10-21.
Checked by a second AI model, 2026-10-25.
In the claim ledger
^ a b c d eAn object's type indexes UpdateObject_JumpTable, whose routines name the monsters: Lynel $01, Moblin $03–$04, Goriya $05–$06, Octorok $07–$0A, Darknut $0B–$0C, Tektite $0D–$0E, Leever $0F–$10, Vire $12, Zol $13, Gel $14–$15, Pols Voice $16, Like Like $17, Keese $1B–$1D, Ghini $21–$22, Wizzrobe $23–$24, Wallmaster $27, Rope $28, Stalfos $2A, Gibdo $30, and Ganon $3E.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
5322    .ADDR DoNothing
5323    .ADDR UpdateLynel
5324    .ADDR UpdateLynel
5325    .ADDR UpdateMoblin
5326    .ADDR UpdateMoblin
⋮
5329    .ADDR UpdateOctorock
5330    .ADDR UpdateOctorock
5331    .ADDR UpdateOctorock
5332    .ADDR UpdateOctorock
⋮
5342    .ADDR UpdateGel
5343    .ADDR UpdateGel
⋮
5347    .ADDR DoNothing
⋮
```
src/Z_07.asm lines 5321–5384 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 7 $FBB4, the jump table. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^Each level of ring halves the damage before it is subtracted, so the first ring takes half and the second a quarter.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
5750    ; For every level of ring (1 or 2), divide the 16-bit damage amount in [0E:0D] by 2.
5751    LDY InvRing
5752    BEQ @ResetHelp
⋮
5754    LSR $0D
5755    ROR $0E
5756    DEY
5757    BNE :-
```
src/Z_01.asm lines 5750–5757 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1 CheckLinkCollision through Link_BeHarmed, run from RAM at $7AA7. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^When the partial heart can't cover the damage, the game takes a full heart and refills the partial heart to $FF rather than $100, so each such borrow costs Link an extra 1/256 of a heart.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
5789@BorrowHeart:
5790    ; This isn't a simple case of borrowing. For example, supposing:
5791    ;   full heart=4 partial heart=$70
5792    ; The straightforward way to subtract $80 would yield $3F0.
5793    ; But the method here yields $3EF, because partial heart is
5794    ; considered full when = $FF instead of $100.
⋮
5802    DEC HeartValues
5803    LDA #$FF
5804    STA HeartPartial
```
src/Z_01.asm lines 5789–5805 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1, as in ring. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^ a b c dMeasured in Rev 1, a Tektite held against Link hurts him every 47 or 48 frames, taking half a heart each time; from three hearts, five hits leave $20 and $7D, 3/256 of a heart under a half heart.Verified“Legend of Zelda, The (USA) (Rev 1)” · aldonunez/zelda1-disassembly
How we know
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1, the contact check and damage the probe exercises. We don't reproduce the bytes.
```
5769    LDA HeartPartial
5770    CMP $0E
5771    BCC @BorrowHeart
5772    SEC
5773    SBC $0E
5774    STA HeartPartial
⋮
5784    SEC
⋮
5796    SEC
⋮
5802    DEC HeartValues
5803    LDA #$FF
5804    STA HeartPartial
⋮
5817    STA HeartPartial
```
src/Z_01.asm lines 5600–5822 at 50a1c86 · upstream ↗
Measured by a script in MesenCE 2.2.1 (build 4b8a196), on Legend of Zelda, The (USA) (Rev 1) (SHA-1 4671517d72d0…). It fails if the result disagrees with the claim.
The numbers come from the run; its author, an AI model, checked the script measures what the claim says, 2026-10-25.
Checked by a second AI model, 2026-10-21.
Checked by a second AI model, 2026-10-25.
In the claim ledger

^ a bA monster that touches Link while his invincibility timer is above 0 does nothing; a hit sets the timer to 24 and his shove distance to 32 px.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”

How we know

5610    ; If Link is invincible, or we have the magic clock,
5611    ; or Link is stunned, or the monster is stunned;
5612    ; then return no collision.
5613    LDA ObjInvincibilityTimer
5614    ORA InvClock
5615    ORA ObjStunTimer
5616    ORA ObjStunTimer, X
5617    BNE L73A9_Exit

src/Z_01.asm lines 5610–5617 at 50a1c86 · upstream ↗

6589    ; If Link is invincible, return without shoving.
6590    LDA ObjInvincibilityTimer
6591    BNE @Exit
⋮
6601    ; Mark Link invincible $18 frames, and should move $20 pixels.
6602    LDA #$18
6603    STA ObjInvincibilityTimer
6604    LDA #$20
6605    STA ObjShoveDistance

src/Z_01.asm lines 6589–6605 at 50a1c86 · upstream ↗

In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1 BeginShove, run from RAM at $7E26. We don't reproduce the bytes.

Checked against the evidence by its author, an AI model, 2026-10-20.

Checked by a second AI model, 2026-10-21.

In the claim ledger

^DecrementInvincibilityTimer lowers an object's invincibility timer by 1 only on frames when FrameCounter is even, so a timer of $t$ lasts $2 t$ frames.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
5782DecrementInvincibilityTimer:
5783    LDA ObjInvincibilityTimer, X
5784    BEQ @Exit                   ; If the timer is already zero, then return.
5785    LDA FrameCounter            ; Every two frames, decrease the timer.
5786    LSR
5787    BCS @Exit
5788    DEC ObjInvincibilityTimer, X
```
src/Z_07.asm lines 5782–5788 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 7 $FE98. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^While Link holds the clock, BeginUpdateWorld adds 16 to his invincibility timer every frame, and monsters' contact checks return no collision.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
1876BeginUpdateWorld:
1877    ; If we have the clock, then
1878    ; force the player's invincibility.
1879    LDA InvClock
1880    BEQ @NotInvincible
1881    LDA ObjInvincibilityTimer
1882    CLC
1883    ADC #$10
1884    STA ObjInvincibilityTimer
```
src/Z_07.asm lines 1876–1884 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 7 $EC7A, these lines only; BeginUpdateWorld differs in Rev 1 further on. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^ a b cA shoved object moves 4 px a frame, 1 px of shove distance at a time, and the shove ends early when the object reaches the room's edge or, aligned to the grid, an unwalkable tile.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
2397ShoveMoveMin:
2398    ; Try to move 4 pixels. [03] is the counter.
2399    LDA #$04
2400    STA $03
⋮
2411    JSR GetCollidingTileMoving
2412    CMP ObjectFirstUnwalkableTile
2413    BCS ResetShoveInfo
⋮
2416    ; Regardless of the grid offset, if the object runs into the
2417    ; bounds of the room, then stop shoving.
```
src/Z_07.asm lines 2397–2420 at 50a1c86 · upstream ↗
```
2450    ; We're OK to change the position. So, decrease the distance
2451    ; that's left to move.
2452    DEC ObjShoveDistance, X
```
src/Z_07.asm lines 2450–2452 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 7 Obj_Shove and ShoveMoveMin, $EEB8. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^ a bWhen a monster hits Link, the shove points away from the monster along one axis: the horizontal one when Link is between grid squares and faces left or right, the vertical one when he is between squares facing up or down. The monster then turns around, unless bit 7 of its object attributes is set (a flag the disassembly's comments name "reverse after hit Link") or it is a Vire (object type $12).Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
6528    LDA #$08
6529    STA $08
6530    LDA ObjY, X
6531    STA $04
6532    LDA a:ObjY, Y
6533    STA $05
⋮
6538    CPY #$00
6539    BNE :+
6540    LDA ObjGridOffset
6541    BEQ :+
6542    LDA ObjDir
6543    AND #$03
⋮
```
src/Z_01.asm lines 6528–6581 at 50a1c86 · upstream ↗
```
6597    LDA $08
6598    ORA #$80
6599    STA ObjShoveDir
```
src/Z_01.asm lines 6597–6599 at 50a1c86 · upstream ↗
```
6614    ; If the monster's object attribute "reverse after hit Link" is set,
6615    ; then return.
6616    LDA ObjAttr, X
6617    AND #$80
6618    BNE @Exit
⋮
6621    LDA ObjType, X
6622    CMP #$12
6623    BEQ @Exit
⋮
6626    LDA ObjDir, X
6627    JSR GetOppositeDir
6628    STA ObjDir, X
```
src/Z_01.asm lines 6612–6628 at 50a1c86 · upstream ↗
```
5321UpdateObject_JumpTable:
5322    .ADDR DoNothing
⋮
5340    .ADDR UpdateVire
```
src/Z_07.asm lines 5321–5340 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1 BeginShove. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-25.
Checked by a second AI model, 2026-10-21.
Checked by a second AI model, 2026-10-25.
In the claim ledger
^Walker_Move moves a walking object by its shove whenever one is set, in place of its walking, so Link can't steer during a shove.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
2600Walker_Move:
2601    ; If the object is being shoved, then go shove it.
2602    LDA ObjShoveDir, X
2603    BEQ @ChooseObjDirOrInputDir
2604    JMP Obj_Shove
```
src/Z_07.asm lines 2600–2604 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 7 $EFD0. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^ a bMeasured in Rev 1, each of the Tektite's first three hits shoves Link 32 px to the right in 8 frames.Verified“Legend of Zelda, The (USA) (Rev 1)” · aldonunez/zelda1-disassemblyrevised
How we know
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 7 Obj_Shove and ShoveMoveMin, which move Link in the probe. We don't reproduce the bytes.
```
2348    LDA ObjGridOffset, X
⋮
2397ShoveMoveMin:
⋮
2399    LDA #$04
2400    STA $03
⋮
2405    LDA ObjGridOffset, X
⋮
2452    DEC ObjShoveDistance, X
⋮
2455    LDA ObjGridOffset, X
2456    CLC
2457    ADC $02
2458    STA ObjGridOffset, X
⋮
2470    STA ObjGridOffset, X
```
src/Z_07.asm lines 2323–2470 at 50a1c86 · upstream ↗
Measured by a script in MesenCE 2.2.1 (build 4b8a196), on Legend of Zelda, The (USA) (Rev 1) (SHA-1 4671517d72d0…). It fails if the result disagrees with the claim.
The numbers come from the run; its author, an AI model, checked the script measures what the claim says, 2026-10-25.
Checked by a second AI model, 2026-10-21.
Revised after a check by a second AI model, 2026-10-25.
In the claim ledger
^The wooden, white, and magical swords take $10, $20, and $40 from a monster's hit points; fire takes $10, a bomb $40, and the boomerang none, only stunning.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
6162SwordDamagePoints:
6163    .BYTE $10, $20, $40
```
src/Z_01.asm lines 6162–6163 at 50a1c86 · upstream ↗
```
6111    ; Set up parameters for a fire.
⋮
6114    LDA #$10
6115    STA $07                     ; [07] holds $10 damage points
⋮
6127    ; Else set up parameters for a bomb.
⋮
6130    LDA #$40
6131    STA $07                     ; [07] holds $40 damage points
```
src/Z_01.asm lines 6111–6131 at 50a1c86 · upstream ↗
```
5914    ; Still the boomerang.
5915    ; Reset [07] damage points, and set the monster's stun timer to $10 ($A0 frames).
5916    LDA #$00
5917    STA $07
5918    LDA #$10
5919    STA ObjStunTimer, X
```
src/Z_01.asm lines 5914–5919 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1 CheckMonsterBombOrFireCollision through CheckMonsterSwordCollision. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-25.
Checked by a second AI model, 2026-10-21.
Checked by a second AI model, 2026-10-25.
In the claim ledger

^ a bA weapon that hurts a monster sets the monster's invincibility timer to 16, which lasts 32 frames, and shoves it 64 px in the weapon's direction, unless the monster is already invincible or immune to the weapon's damage type.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”

How we know

6503BeginShove:
6504    ; If a weapon attacks a monster, and the weapon's damage
6505    ; type matches the monster's invincibility mask;
6506    ; then return without shoving.

src/Z_01.asm lines 6503–6514 at 50a1c86 · upstream ↗

6636    ; Set the shove direction to the weapon's direction,
⋮
6653    ; If the monster is invincible, then return without shoving.
6654    LDA ObjInvincibilityTimer, X
6655    BNE @Exit2
⋮
6671    BNE @Exit2
⋮
6676    BNE @Exit2
⋮
6687    ; Mark the monster invincible $10 frames, and should move $40 pixels.
6688    LDA #$40
6689    STA ObjShoveDistance, X
6690    LDA #$10
6691    STA ObjInvincibilityTimer, X

src/Z_01.asm lines 6636–6691 at 50a1c86 · upstream ↗

In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1 BeginShove. We don't reproduce the bytes.

Checked against the evidence by its author, an AI model, 2026-10-20.

Checked by a second AI model, 2026-10-21.

In the claim ledger

^ a b c d e fSetUpDroppedItem sorts a dead monster's type into one of four drop groups by three type lists, with every unlisted type in the fourth; seven types, among them the Gels, the Keese, and the Like Like, drop nothing.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
11030; Types of objects that do not drop items.
⋮
11032NoDropMonsterTypes:
11033    .BYTE $5D, $14, $15, $1B, $1C, $1D, $17
⋮
11035DropItemMonsterTypes0:
11036    .BYTE $07, $08, $0E, $04, $0F, $23
⋮
11038DropItemMonsterTypes1:
11039    .BYTE $21, $22, $0D, $10, $13, $28, $2A, $27
11040    .BYTE $16
⋮
11042DropItemMonsterTypes2:
11043    .BYTE $09, $0A, $03, $01, $12, $06, $0B, $24
11044    .BYTE $30
```
src/Z_04.asm lines 11030–11044 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 4 $B01B, the lists, tables, and SetUpDroppedItem. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger

^ a b c d e fDropItemTable holds ten items for each group, and the kill cycle picks the column; group A's row is heart, rupee, heart, rupee, fairy, rupee, heart, heart, rupee, rupee.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”

How we know

11057; ID's for items dropped by monsters.
11058; WorldKillCycle addresses the column.
⋮
11060; Monsters are arranged in groups that determine the row.
11061; There are four rows.
⋮
11063DropItemTable:
11064    .BYTE $22, $18, $22, $18, $23, $18, $22, $22
11065    .BYTE $18, $18, $0F, $18, $22, $18, $0F, $22
11066    .BYTE $21, $18, $18, $18, $22, $00, $18, $21
11067    .BYTE $18, $22, $00, $18, $00, $22, $22, $22
11068    .BYTE $23, $18, $22, $23, $22, $22, $22, $18

src/Z_04.asm lines 11057–11068 at 50a1c86 · upstream ↗

11137    LDY $01
11138    LDA DropItemSetBaseOffsets, Y
11139    CLC
11140    ADC WorldKillCycle
11141    TAY
11142    LDA DropItemTable, Y
11143    STA $00                     ; [00] Dropped item ID

src/Z_04.asm lines 11137–11143 at 50a1c86 · upstream ↗

In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 4, as in drop-groups. We don't reproduce the bytes.

Checked against the evidence by its author, an AI model, 2026-10-20.

Checked by a second AI model, 2026-10-21.

In the claim ledger

^ a b c d e fOutside the special cases, a drop happens only when the dead monster's slot's byte of Random is below its group's rate: $50, $98, $68, and $68, or 80, 152, 104, and 104 in 256.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
11051; Top drop an item, a random value must be less than the
11052; element for the monster group.
⋮
11054DropItemRates:
11055    .BYTE $50, $98, $68, $68
```
src/Z_04.asm lines 11051–11055 at 50a1c86 · upstream ↗
```
11176@RandomlyCancel:
11177    ; If the random value >= drop item rate for the monster's group,
11178    ; then go destroy the monster.
11179    LDY $01
11180    LDA Random, X
11181    CMP DropItemRates, Y
11182    BCS @DestroyMonster
```
src/Z_04.asm lines 11176–11182 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 4, as in drop-groups. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^ a bEach kill advances WorldKillCycle from 0 to 9 and back to 0 before the drop is chosen, except kills of types $5D, $14, and $1C, which the comments call a Child Gel and a Red Keese.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
5457    ; Certain objects don't advance the world kill cycle.
5458    CMP #$5D
5459    BEQ @DropItem
5460    CMP #$14                    ; Child Gel
5461    BEQ @DropItem
5462    CMP #$1C                    ; Red Keese
5463    BEQ @DropItem
⋮
5465    ; Advance the world kill cycle (0 to 9).
5466    LDA WorldKillCycle
5467    CLC
5468    ADC #$01
5469    CMP #$0A
⋮
```
src/Z_07.asm lines 5457–5488 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 7 UpdateMetaObjectEnd, $FC95. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^Whenever Link is hurt, the game zeroes WorldKillCount, HelpDropCount, and HelpDropValue, the counters behind the fairy and the 10th-kill drops.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
5759@ResetHelp:
5760    ; Reset values used in special item drops.
5761    LDA #$00
5762    STA WorldKillCount
5763    STA HelpDropCount
5764    STA HelpDropValue
```
src/Z_01.asm lines 5759–5764 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1, as in ring. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger
^When WorldKillCount, the kills since Link was last hurt, equals 16 and the monster can drop items, the drop is a fairy, whatever its random byte.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
11145    ; If the global kill count = $10, set the dropped item to a fairy.
11146    LDA #$23
11147    LDY WorldKillCount
11148    CPY #$10
11149    BEQ @SetHelpItem
```
src/Z_04.asm lines 11145–11149 at 50a1c86 · upstream ↗
```
5996HandleMonsterDied:
5997    ; Handle the monster dying.
5998    INC WorldKillCount
```
src/Z_01.asm lines 5996–5998 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 4, as in drop-groups. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger

^The 10th kill since Link was last hurt brings a guaranteed drop of 5 rupees, or of bombs when that 10th kill was by bomb, and the count starts again from 0.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”

How we know

6000    ; Increase the help drop counter, if not at max ($A).
6001    LDA HelpDropCount
6002    CMP #$0A
6003    BCS @SetDyingMetastate
6004    INC HelpDropCount
⋮
6006    ; If the help drop counter has reached the max, and damage type = bomb (8);
6007    ; then set [51] HelpDropValue in order to drop a bomb next time.

src/Z_01.asm lines 6000–6007 at 50a1c86 · upstream ↗

11151    ; If help drop counter < $A, then use the dropped item ID as is.
11152    ; But there is a random chance that the item drop will be canceled.
⋮
11157    ; Otherwise, the item will be guaranteed to be made.
11158    ; [51] HelpDropValue determines which kind:
11159    ; - 0:     5 rupees
11160    ; - other: bomb
⋮
11172    STA HelpDropCount
11173    STA HelpDropValue

src/Z_04.asm lines 11151–11173 at 50a1c86 · upstream ↗

In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 4, as in drop-groups. We don't reproduce the bytes.

Checked against the evidence by its author, an AI model, 2026-10-20.

Checked by a second AI model, 2026-10-21.

In the claim ledger

^In TakeItem, item $18 is a rupee, $0F five rupees, $22 a heart, $23 a fairy, $21 the clock, and $00 four bombs; a heart restores 1 heart and a fairy 3.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”

How we know

4318ItemIdToSlot:
4319    .BYTE $01, $00, $00, $00, $06, $05, $04, $04
4320    .BYTE $02, $02, $03, $0D, $09, $0C, $1B, $1C
4321    .BYTE $08, $0A, $0B, $0B, $0E, $0F, $10, $11
4322    .BYTE $16, $17, $18, $1A, $1F, $1D, $1E, $07
4323    .BYTE $07, $15, $19, $14
⋮
4341ItemIdToDescriptor:
4342    .BYTE $14, $21, $22, $23, $01, $01, $21, $22
4343    .BYTE $21, $22, $01, $01, $01, $01, $01, $15
4344    .BYTE $01, $01, $21, $22, $01, $01, $01, $01
4345    .BYTE $11, $11, $10, $01, $01, $01, $01, $11
4346    .BYTE $22, $01, $10, $12

src/Z_01.asm lines 4318–4346 at 50a1c86 · upstream ↗

4540    CPY #$18                    ; Heart container item slot
4541    BEQ @TakeHeartContainer
4542    CPY #$1C                    ; 5 Rupees item slot
4543    BEQ Take5Rupees
4544    CPY #$16                    ; Rupee item slot
4545    BEQ @TakeRupee

src/Z_01.asm lines 4540–4545 at 50a1c86 · upstream ↗

4651TakeHeartsNoSound:
4652    LDA $0A                     ; Move item value in [0A] to [01].
4653    STA $01                     ; [01] holds the number of hearts to add minus 1.

src/Z_01.asm lines 4651–4653 at 50a1c86 · upstream ↗

In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1 TakeItem through the heart routines, run from RAM at $7370. We don't reproduce the bytes.

Checked against the evidence by its author, an AI model, 2026-10-20.

Checked by a second AI model, 2026-10-21.

In the claim ledger

^A dropped item lasts 255 decrements of its lifetime, one every other frame, about 510 frames, and Link can't take it until the 16th decrement, about 32 frames.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”revised
How we know
```
11206UpdateItem:
11207    ; Every other frame, decrement the item lifetime.
11208    LDA FrameCounter
11209    LSR
11210    BCC :+
11211    DEC Item_ObjItemLifetime, X
⋮
11213    ; If lifetime reached 0, go destroy the object.
11214    LDA Item_ObjItemLifetime, X
11215    BEQ DestroyMonster_Bank4
```
src/Z_04.asm lines 11206–11215 at 50a1c86 · upstream ↗
```
4417    ; [03A8][X] is used to count down the life of the item.
4418    LDA Item_ObjItemLifetime, X
4419    CMP #$F0
4420    BCS L6C28_Exit
```
src/Z_01.asm lines 4416–4420 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 4 UpdateItem, $B0FC. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Revised after a check by a second AI model, 2026-10-21: Pickup is blocked for 16 lifetime decrements, not 15.
In the claim ledger
^ a bCalled in Rev 1 for every group, kill-cycle column, and value of the random byte, SetUpDroppedItem drops in 800, 1,520, 1,040, and 1,040 of 2,560 cases for groups A to D, each the item its column names; it gives a fairy at a kill count of 16, and 5 rupees or bombs at a help count of 10.Verified“Legend of Zelda, The (USA) (Rev 1)” · aldonunez/zelda1-disassembly
How we know
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 4, the routine and tables the probe calls. We don't reproduce the bytes.
```
11138    LDA DropItemSetBaseOffsets, Y
⋮
11140    ADC WorldKillCycle
⋮
11142    LDA DropItemTable, Y
⋮
11147    LDY WorldKillCount
11148    CPY #$10
⋮
11153    LDA HelpDropCount
11154    CMP #$0A
⋮
11180    LDA Random, X
11181    CMP DropItemRates, Y
11182    BCS @DestroyMonster
```
src/Z_04.asm lines 11070–11201 at 50a1c86 · upstream ↗
Measured by a script in MesenCE 2.2.1 (build 4b8a196), on Legend of Zelda, The (USA) (Rev 1) (SHA-1 4671517d72d0…). It fails if the result disagrees with the claim.
The numbers come from the run; its author, an AI model, checked the script measures what the claim says, 2026-10-25.
Checked by a second AI model, 2026-10-21.
Checked by a second AI model, 2026-10-25.
In the claim ledger
^The Speed Demos Archive Knowledge Base states that 10 kills without being hit force a 5-rupee drop, or a bomb when the 10th is killed by bomb, and that 16 kills in a row force a fairy, only when the 16th enemy can drop items.WikiSpeed Demos Archive, “The Legend of Zelda”revised
How we know
Kill 10 enemies without getting hit and you’ll get a forced, guaranteed 5 rupee drop … Kill the 10th enemy with a bomb instead, and instead of a 5 rupee you’ll get a forced, guaranteed bomb drop! Kill 16 enemies in a row and you get a fairy drop forced, but only if the 16th enemy is capable of dropping an item
Enemy drops · archived copy ↗
The quote matches our archived copy.
Revised after a check by a second AI model, 2026-10-21.
In the claim ledger
^A heart container adds one container and one full heart, up to 16 containers; a new file starts with three.Codealdonunez/zelda1-disassembly · “Legend of Zelda, The (USA) (Rev 1)”
How we know
```
4585@TakeHeartContainer:
4586    ; For heart containers, cap at $10.
4587    ; Add a heart container and a heart.
4588    LDA Items, Y
4589    CMP #$F0
4590    BCS L6C28_Exit              ; If we already have max hearts, return.
4591    ADC #$11
4592    JMP SetItemValue            ; Go set the item value and return.
```
src/Z_01.asm lines 4585–4592 at 50a1c86 · upstream ↗
In the cartridge (“Legend of Zelda, The (USA) (Rev 1)”): bank 1, as in item-ids. We don't reproduce the bytes.
Checked against the evidence by its author, an AI model, 2026-10-20.
Checked by a second AI model, 2026-10-21.
In the claim ledger

Sources

Code

n.d. “Legend of Zelda, The (USA) (Rev 1).” · licence, all uses
Núñez, Aldo. 2021. “zelda1-disassembly: A complete disassembly of The Legend of Zelda.” Commit 50a1c86. aldonunez/zelda1-disassembly @ 50a1c86 · licence, all uses

Secondary

Wikidata contributors. 2026. “Wikidata.” Wikimedia Foundation. original · licence, all uses
Speed Demos Archive Knowledge Base contributors. 2013. “The Legend of Zelda.” Speed Demos Archive. original · archived · licence, all uses

#Hearts and damage

#Invincibility after a hit

#The shove

#Hitting monsters

#Item drops

#Health growth

Related

Mentioned in

Mechanics

References

Sources

Code

Secondary