Game
EarthBound
The 1994 Super Famicom sequel to Mother, read through the US release in Herringway's ebsrc disassembly.
On this page
EarthBound is the North American release of Mother 2, the Super Famicom sequel to Mother. The code read here is Herringway’s ebsrc, a ca65 disassembly that builds the US release, a US prototype, and the Japanese Mother 2 from one source. The claims describe the US release.
Damage to a party member doesn’t land at once. It sets a target, and the HP meter counts toward it at 1.0625 to 1.125 HP per update; a character falls only when the meter reaches 0, so a battle won while it is still rolling leaves them standing1. This is the rolling HP meter.
Enemies walk the map instead of appearing at random. Touching one starts a battle, and the facings at contact decide who strikes first2. Enemies far below the party’s levels run from it3, and a fight the party can’t lose is won without being fought, the instant win4.
A bash deals twice the Offense less the Defense, give or take up to a quarter5. It can miss on the weapon’s rate in 16, and then the target can dodge by Speed6. A “SMAAAASH!!” comes at about Guts in 500 and deals 4 × Offense − Defense7. As in Mother it is rolled before the dodge, but every number has changed8. The turn order rolls Speed up or down by as much as half once per turn9, and running gets 10 points likelier each turn10.
Mechanics
| Mechanic | Kind | How |
|---|---|---|
| Rolling HP meter | Rolling | a party member's HP counts down to the damage at about 1 HP per update, and only the rolled value knocks them out |
| Instant win | Guaranteed win | skipped when the party's weakest bash would kill every enemy and its slowest member outruns them all, or the first strike plays out a win |
| Visible encounter | Touch and facing | enemies walk the map; who faces whom at contact decides the first strike, and enemies far below the party run away |
| Turn order | Stat plus a roll | Speed ±50%, rolled once per turn, highest first |
| Damage formula | Attack minus defense | 2 × Offense − Defense, ±25% weighted toward small changes |
| Critical hit | From a stat | "SMAAAASH!!" at about Guts in 500, at least 1 in 20 for the party, for 4 × Offense − Defense |
| Hit chance | Miss, then a stat dodge | a miss roll in 16 from the weapon, then a dodge of (2 × the target's Speed − the attacker's) in 500 |
| Fleeing | Speed gap, rising by turn | 10 × the turn number plus the Speed gap, in 100; certain on a first strike, never against a boss |
Every claim about this game, by concept (10)
References
- ^In EarthBound (US release), damage to a party member sets a target HP, and the HP shown counts toward it over time: each call moves one party slot (picked by the frame counter's low two bits) by 1.125, 1.094, or 1.0625 HP by the text speed setting. Healing rolls at 6.25 HP per update when a fastest flag or the flip-out mode is set; damage rolls at 6.25 only in the flip-out mode. A character falls only when that rolling HP reaches 0. When the last enemy falls, each meter still rolling down stops where it is, so mortal damage that hasn't finished rolling doesn't knock anyone out. Enemies and guest characters take damage at once.CodeHerringway/ebsrc · “EarthBound (USA)”revised
How we know
23 LDA a:battler::ally_or_enemy,X 24 AND #$00FF 25 BNE @UNKNOWN2 26 LDA a:battler::npc_id,X 27 AND #$00FF 28 BNE @UNKNOWN1 29 TYA 30 STA a:battler::hp_target,X ⋮ 32 AND #$00FF ⋮ 37 TYA 38 STA PARTY_CHARACTERS+char_struct::current_hp_target,X 39 BRA @UNKNOWN3 ⋮
src/battle/set_hp.asm lines 23–64 at 68aec5c · upstream ↗ 12 LDA FRAME_COUNTER 13 AND #$00FF 14 AND #$0003 ⋮ 22 LDA GAME_STATE + game_state::party_members,X
src/misc/hp_pp_roller.asm lines 12–22 at 68aec5c · upstream ↗ 64 LDA FASTEST_HPPP_METER_SPEED 65 AND #$00FF 66 BNE @UNKNOWN5 67 LDA HPPP_METER_FLIPOUT_MODE 68 BEQ @UNKNOWN6 69@UNKNOWN5: 70 MOVE_INT_CONSTANT $00064000, @VIRTUAL06 71 BRA @UNKNOWN7 72@UNKNOWN6: 73 JSR UNKNOWN_C20F58 ⋮ 79 ADD_INT_ASSIGN @VIRTUAL06, @VIRTUAL0A
src/misc/hp_pp_roller.asm lines 64–80 at 68aec5c · upstream ↗ 109@UNKNOWN10: ⋮ 116 LDA HPPP_METER_FLIPOUT_MODE 117 BEQ @UNKNOWN11 118 MOVE_INT_CONSTANT $00064000, @VIRTUAL06 119 BRA @UNKNOWN12 120@UNKNOWN11: 121 JSR UNKNOWN_C20F58 ⋮ 127 SUB_INT_ASSIGN @VIRTUAL06, @VIRTUAL0A
src/misc/hp_pp_roller.asm lines 109–127 at 68aec5c · upstream ↗ 2HP_METER_SPEEDS: 3 .WORD $2000, 1 ;1 + 4/32 4 .WORD $1800, 1 ;1 + 3/32 5 .WORD $1000, 1 ;1 + 2/32
src/data/hp_meter_speeds.asm lines 2–5 at 68aec5c · upstream ↗ In the cartridge (“EarthBound (USA)”): $C3:FB1F, the three 32-bit rates as the ROM has them. We don't reproduce the bytes.
665 LDA GAME_STATE+game_state::text_speed ⋮ 670 LOADPTR HP_METER_SPEEDS, @VIRTUAL0A ⋮ 678 MOVE_INT @VIRTUAL06, HP_METER_SPEED
src/intro/file_select_menu_loop.asm lines 665–678 at 68aec5c · upstream ↗ 43 LDA a:char_struct::current_hp,X 44 LDX @LOCAL01 45 STA __BSS_START__,X ⋮ 49 LDX @LOCAL01 50 LDA __BSS_START__,X 51 BNE @UNKNOWN4 ⋮ 62 LDA #STATUS_0::UNCONSCIOUS 63 STA a:battler::afflictions + STATUS_GROUP::PERSISTENT_EASYHEAL,X
src/battle/check_dead_players.asm lines 43–63 at 68aec5c · upstream ↗ 3051@ALLIES_ARE_ALIVE: 3052 LDA #1 3053 JSL COUNT_CHARS 3054 CMP #0 3055 BNEL @UNKNOWN234 3056@ENEMIES_ARE_DEAD: 3057 STZ @LOCAL03 3058 JSL RESET_HPPP_ROLLING
src/battle/main_battle_routine.asm lines 3051–3058 at 68aec5c · upstream ↗ 37 LDA a:char_struct::current_hp_fraction,Y 38 BEQ @UNKNOWN2 39 LDA a:char_struct::current_hp,Y 40 STA @LOCAL00 ⋮ 43 ADC #char_struct::current_hp_target ⋮ 47 LDA @LOCAL00 48 CMP @VIRTUAL04 49 BLTEQ @UNKNOWN2 50 STA __BSS_START__,X
src/misc/reset_hppp_rolling.asm lines 37–50 at 68aec5c · upstream ↗ Checked against the evidence by its author, an AI model, 2026-10-21.
Revised after a check by a second AI model, 2026-10-21.
- ^In EarthBound (US release), a battle starts when an enemy on the map touches the party, and the two's facings decide who strikes first. With the direction from the enemy to the party rounded to one of eight: the party strikes first when the enemy isn't moving toward the party (within 45°) and the leader isn't facing away from the enemy; the enemies strike first when the enemy is moving toward the party and the leader faces away; otherwise neither does. A standing enemy always gives the party the first strike.CodeHerringway/ebsrc
How we know
17 LDA TOUCHED_ENEMY ⋮ 24 ADC #.LOWORD(ENTITY_MOVING_DIRECTIONS) ⋮ 28 CMP #8 29 BNE @UNKNOWN0 30 LDY #0 31 LDX #1 32 BRA @UNKNOWN6
src/unknown/C0/C0D19B.asm lines 17–32 at 68aec5c · upstream ↗ 49 JSL UNKNOWN_C41EFF 50 LDY #$2000 51 CLC 52 ADC #$1000 53 JSL DIVISION16S_DIVISOR_POSITIVE 54 STA @VIRTUAL04 ⋮ 57 SEC 58 SBC @VIRTUAL04 59 AND #$0007 60 BEQ @UNKNOWN1 61 CMP #1 62 BEQ @UNKNOWN1 ⋮
src/unknown/C0/C0D19B.asm lines 49–99 at 68aec5c · upstream ↗ Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
- ^In EarthBound (US release), an enemy on the map turns and runs from the party when its group's run-away event flag holds the value the group names (its run_away_flag_state byte), or when the levels of the party's main characters (not guests) summed are more than 10 times the enemy's level; more than 8 times for 3 enemies in 4, and more than 6 times for 1 in 2, by a random byte each enemy gets when it spawns.CodeHerringway/ebsrcrevised
How we know
24 OPTIMIZED_ADD battle_entry_ptr_entry::run_away_flag ⋮ 31 JSL GET_EVENT_FLAG ⋮ 36 ADC #battle_entry_ptr_entry::run_away_flag_state ⋮ 43 LDA @LOCAL00 44 CMP @VIRTUAL02 45 BNE @UNKNOWN0 46 LDA #1
src/unknown/C0/C0C524.asm lines 24–47 at 68aec5c · upstream ↗ 49 JSL UNKNOWN_C0546B ⋮ 53 ASL ⋮ 60 ADC #enemy_data::level ⋮ 65 OPTIMIZED_MULT @VIRTUAL04, 10 66 STA @VIRTUAL02 67 LDY @LOCAL00 68 TYA 69 CMP @VIRTUAL02 70 BLTEQ @UNKNOWN1 71 LDA #1 ⋮ 73@UNKNOWN1: 74 LDA @LOCAL01 ⋮
src/unknown/C0/C0C524.asm lines 49–105 at 68aec5c · upstream ↗ 2UNKNOWN_C0C615: 3 REP #PROC_FLAGS::ACCUM8 | PROC_FLAGS::INDEX8 | PROC_FLAGS::CARRY 4 JSL UNKNOWN_C0C524 5 CMP #$0000 6 BEQ @UNKNOWN0 7 JSL GET_OPPOSITE_DIRECTION_FROM_PLAYER_TO_ENTITY
src/unknown/C0/C0C615.asm lines 2–11 at 68aec5c · upstream ↗ 412 JSL RAND 413 LDX @LOCAL06 414 STA ENTITY_WEAK_ENEMY_VALUE,X
src/overworld/spawn_enemies_from_group.asm lines 412–414 at 68aec5c · upstream ↗ Checked against the evidence by its author, an AI model, 2026-10-21.
Revised after a check by a second AI model, 2026-10-21.
- ^In EarthBound (US release), a battle the party can't lose is won without being fought. The check fails if the enemies struck first, or if there are more enemies than able party members among the four main characters (unconscious, diamondized, paralyzed, nauseous, poisoned, sunstroked, cold, mushroomized, and possessed ones don't count). In an even start, the four's lowest Speed must be at least every enemy's Speed, and twice their lowest Offense at least each enemy's HP plus Defense. When the party struck first, it sorts the able members by Offense and the enemies by HP, both highest first, and plays one round in that order: each member makes one attack of 2 × Offense − Defense on the current enemy, moving on to the next enemy only when one falls (any surplus damage is lost), and the party wins if every enemy falls.CodeHerringway/ebsrcrevised
How we know
17 LDA BATTLE_INITIATIVE 18 CMP #INITIATIVE::ENEMIES_FIRST 19 BNE @UNKNOWN0 20 LDA #0 21 JMP @UNKNOWN37
src/battle/instant_win_check.asm lines 17–21 at 68aec5c · upstream ↗ 46 CPX #1 47 BCCL @UNKNOWN6 48 CPX #4 49 BGTL @UNKNOWN6 ⋮ 55 LDA PARTY_CHARACTERS+char_struct::speed,X 56 AND #$00FF 57 CMP @VIRTUAL04 58 BCS @UNKNOWN4 59 STA @VIRTUAL04
src/battle/instant_win_check.asm lines 46–59 at 68aec5c · upstream ↗ 130 LDA ENEMIES_IN_BATTLE 131 CMP @LOCAL08 132 BLTEQ @UNKNOWN9 133 LDA #0 134 JMP @UNKNOWN37 135@UNKNOWN9: 136 LDA BATTLE_INITIATIVE 137 BNEL @UNKNOWN18
src/battle/instant_win_check.asm lines 130–137 at 68aec5c · upstream ↗ 183 ADC #enemy_data::defense ⋮ 188 STA @VIRTUAL02 ⋮ 191 ADC #enemy_data::hp ⋮ 198 ADC @VIRTUAL02 199 STA @VIRTUAL04 200 LDA @LOCAL07 201 STA @VIRTUAL02 202 ASL 203 CMP @VIRTUAL04 204 BCS @UNKNOWN16 205 LDA #0 206 JMP @UNKNOWN37
src/battle/instant_win_check.asm lines 183–206 at 68aec5c · upstream ↗ 383 LDA INSTANT_WIN_SORTED_OFFENSE,X 384 ASL 385 STA @VIRTUAL04 386 LDX @LOCAL09 ⋮ 388 ASL ⋮ 406 LDA @VIRTUAL04 407 CMP @VIRTUAL02 408 BCS @UNKNOWN34 409 LDA @VIRTUAL04 410 SEC 411 SBC @LOCAL05 ⋮ 414 SEC ⋮
src/battle/instant_win_check.asm lines 383–427 at 68aec5c · upstream ↗ 16 JSL INSTANT_WIN_CHECK 17 CMP #0 18 BEQ @UNKNOWN2 19 JSL INSTANT_WIN_HANDLER 20 STZ BATTLE_MODE 21 BRA @UNKNOWN5 22@UNKNOWN2: 23 JSL INIT_BATTLE_COMMON
src/battle/init_overworld.asm lines 16–23 at 68aec5c · upstream ↗ Checked against the evidence by its author, an AI model, 2026-10-21.
Revised after a check by a second AI model, 2026-10-21.
- ^In EarthBound (US release), a bash deals 2 × the attacker's Offense − the target's Defense, moved up or down by up to 25%, and at least 1. The spread draws two random bytes and keeps the one nearer 128; its distance d from 128 moves the damage by d/512 of it, down when the byte is under 128 and up when over, so small changes are the most common.CodeHerringway/ebsrc
How we know
7 LDX CURRENT_ATTACKER 8 LDA a:battler::offense,X 9 ASL 10 LDX CURRENT_TARGET 11 SEC 12 SBC a:battler::defense,X 13 STA @LOCAL00 14 CLC 15 SBC #0 16 BRANCHLTEQS @UNKNOWN2 17 LDA @LOCAL00 18 JSR TWENTY_FIVE_PERCENT_VARIANCE ⋮
src/battle/actions/level_2_attack.asm lines 7–30 at 68aec5c · upstream ↗ 11 STA @VIRTUAL04 12 JSR RAND_LONG ⋮ 17 JSR RAND_LONG ⋮ 23 SEC 24 SBC #$0080 ⋮ 26 STA @VIRTUAL02 ⋮ 28 CLC 29 SBC @VIRTUAL02 ⋮ 40 SEC 41 SBC #$0080 ⋮ 43 STA @VIRTUAL02 ⋮ 45 CLC ⋮
src/battle/25_percent_variance.asm lines 11–93 at 68aec5c · upstream ↗ Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
- ^In EarthBound (US release), a bash first misses at the attacker's miss rate in 16: for a party member its weapon's, or 1 with no weapon, plus 8 while crying or nauseous; for an enemy its own. Then the target dodges with a chance of about (2 × target's Speed − attacker's Speed) in 500, never when that is 0 or less, nor while the target is paralyzed, asleep, immobilized, or solidified.CodeHerringway/ebsrc
How we know
40 OPTIMIZED_MULT @VIRTUAL04, .SIZEOF(item) 41 CLC 42 ADC #item::params + item_parameters::special ⋮ 45 LDA f:ITEM_CONFIGURATION_TABLE,X ⋮ 52 STX @MISS_CHANCE 53 BRA @UNKNOWN3 54@UNKNOWN2: 55 LDX #1 56 STX @MISS_CHANCE
src/battle/miss_calc.asm lines 40–56 at 68aec5c · upstream ↗ 72 ADC #8 ;miss chance + 1/2 ⋮ 82 ADC #enemy_data::miss_rate ⋮ 89 LDX @MISS_CHANCE 90 BEQ @UNKNOWN9 91 LDA #16 92 JSR RAND_LIMIT 93 STA @VIRTUAL02 94 LDX @MISS_CHANCE 95 TXA 96 DEC 97 CMP @VIRTUAL02 98 BCC @UNKNOWN9
src/battle/miss_calc.asm lines 72–98 at 68aec5c · upstream ↗ 34 LDX CURRENT_TARGET 35 LDA a:battler::speed,X 36 ASL 37 LDX CURRENT_ATTACKER 38 SEC 39 SBC a:battler::speed,X 40 STA @LOCAL00 41 STA @VIRTUAL02 42 LDA #0 43 CLC 44 SBC @VIRTUAL02 45 BRANCHGTS @UNKNOWN6 ⋮
src/battle/determine_dodge.asm lines 34–47 at 68aec5c · upstream ↗ Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
- ^In EarthBound (US release), a bash is a "SMAAAASH!!" with a chance of about the attacker's Guts in 500, with a party member's Guts counted as at least 25 (about 1 in 20). It is rolled after the miss check and before the dodge, so it can't be dodged, and deals 4 × Offense − Defense with no random spread.CodeHerringway/ebsrc
How we know
7 LDA #0 8 JSR MISS_CALC 9 CMP #0 10 BNE @UNKNOWN1 11 JSR SMAAAASH 12 CMP #0 13 BNE @UNKNOWN1 14 JSR DETERMINE_DODGE 15 CMP #0 16 BNE @UNKNOWN0 17 JSR BTLACT_LEVEL_2_ATK
src/battle/actions/bash.asm lines 7–17 at 68aec5c · upstream ↗ 10 LDX CURRENT_ATTACKER 11 LDA __BSS_START__ + battler::guts,X 12 STA @LOCAL01 13 LDX CURRENT_ATTACKER ⋮ 15 AND #$00FF 16 BNE @BYPASS_MINIMUM_GUTS 17 LDA @LOCAL01 18 CMP #GUTS_FLOOR_FOR_SMAAAASH_CHANCE 19 BCS @BYPASS_MINIMUM_GUTS 20 LDA #GUTS_FLOOR_FOR_SMAAAASH_CHANCE 21 STA @LOCAL01 22@BYPASS_MINIMUM_GUTS: ⋮
src/battle/smaaaash.asm lines 10–26 at 68aec5c · upstream ↗ .DEFINE GUTS_FLOOR_FOR_SMAAAASH_CHANCE 25
include/config.asm#L66 · upstream ↗ 59 LDX CURRENT_ATTACKER 60 LDA __BSS_START__ + battler::offense,X 61 ASL 62 ASL 63 LDX CURRENT_TARGET 64 SEC 65 SBC __BSS_START__ + battler::defense,X 66 LDX @LOCAL01 67 JSR CALC_RESIST_DAMAGE
src/battle/smaaaash.asm lines 59–67 at 68aec5c · upstream ↗ 8 STA @VIRTUAL02 9 LDA #500 10 JSR RAND_LIMIT 11 CMP @VIRTUAL02 12 BCS @UNKNOWN0 13 LDA #1
src/battle/success_500.asm lines 8–13 at 68aec5c · upstream ↗ Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
- ^EarthBound (US release) keeps EarthBound Beginnings' order of a plain attack, with the "SMAAAASH!!" rolled before the dodge so it can't be dodged, but changes the numbers: the chance comes from the attacker's Guts alone (about Guts in 500) instead of Fight against Fight; the SMAAAASH deals 4 × Offense − Defense instead of the full Offense; a normal hit deals 2 × Offense − Defense instead of Offense − Defense ÷ 2; and the dodge comes from Speed instead of Fight.CodeNathan-R-Og/mother · Herringway/ebsrc
How we know
585BATTLE_ACTION1: ⋮ 590ba_jumpif BA_CON::IS_CRIT, BA1_CRIT ⋮ 596ba_jumpifnot BA_CON::IS_DODGE, BATACT_DODGED_SWIFTLY ⋮ 602 BA1_CRIT: ⋮ 607ba_misc BA_MISC::DAMAGECALC_CRIT, 0
src/global/battle_data.asm lines 585–608 at e0b3e3f · upstream ↗ 3137BINSTCONDITION2_CRIT: ⋮ 3141 lda BATTLER_CORES, y ⋮ 3144 lda BATTLER_CORES, y ⋮ 3146 jsr DoFightEquation
src/global/prg/battle.asm lines 3137–3146 at e0b3e3f · upstream ↗ 3399; Normal Attack Damage = AttackerOFF - (DefenderDEF / 2) 3400; If DEF > OFF, Damage = (3 * AttackerOFF - DefenderDEF ) / 4 ⋮ 3407 sec ⋮ 3413 sbc battle_wordvar64 ⋮ 3419 bcc @SETNUM_WeakBash 3420 lsr battle_wordvar64+1 3421 ror battle_wordvar64 3422 sec 3423 lda battle_wordvar66 3424 sbc battle_wordvar64 3425 sta battle_wordvar60
src/global/prg/battle.asm lines 3399–3428 at e0b3e3f · upstream ↗ 3483; Damage = AttackerOFF ⋮ 3487 lda BATTLER_OFF, y
src/global/prg/battle.asm lines 3483–3488 at e0b3e3f · upstream ↗ 11 JSR SMAAAASH 12 CMP #0 13 BNE @UNKNOWN1 14 JSR DETERMINE_DODGE 15 CMP #0 16 BNE @UNKNOWN0 17 JSR BTLACT_LEVEL_2_ATK
src/battle/actions/bash.asm lines 11–17 at 68aec5c · upstream ↗ 11 LDA __BSS_START__ + battler::guts,X ⋮ 24 JSR SUCCESS_500
src/battle/smaaaash.asm lines 10–24 at 68aec5c · upstream ↗ 60 LDA __BSS_START__ + battler::offense,X 61 ASL 62 ASL ⋮ 65 SBC __BSS_START__ + battler::defense,X
src/battle/smaaaash.asm lines 60–65 at 68aec5c · upstream ↗ 8 LDA a:battler::offense,X 9 ASL 10 LDX CURRENT_TARGET 11 SEC 12 SBC a:battler::defense,X
src/battle/actions/level_2_attack.asm lines 8–12 at 68aec5c · upstream ↗ 34 LDX CURRENT_TARGET 35 LDA a:battler::speed,X 36 ASL 37 LDX CURRENT_ATTACKER 38 SEC 39 SBC a:battler::speed,X
src/battle/determine_dodge.asm lines 34–39 at 68aec5c · upstream ↗ 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 EarthBound (US release), every conscious combatant's initiative is rolled at the start of each turn: its Speed moved up or down by up to 50% (the 25% spread's method without the final halving), at least 1. Then the conscious combatant yet to act with the highest initiative goes next, ties going to the later slot.CodeHerringway/ebsrc
How we know
1127 LDA a:battler::consciousness,Y 1128 AND #$00FF 1129 BEQ @UNKNOWN73 1130 TYA 1131 CLC 1132 ADC #battler::initiative 1133 STA @VIRTUAL02 1134 LDA a:battler::speed,Y 1135 JSR FIFTY_PERCENT_VARIANCE 1136 LDX @VIRTUAL02 1137 STA __BSS_START__,X 1138 CMP #0 ⋮
src/battle/main_battle_routine.asm lines 1127–1142 at 68aec5c · upstream ↗ 67 LDX @VIRTUAL04 68 TYA 69 SEP #PROC_FLAGS::ACCUM8 70 JSR TRUNCATE_16_TO_8 71 STA @VIRTUAL02 72 LDA @VIRTUAL04 73 SEC 74 SBC @VIRTUAL02
src/battle/50_percent_variance.asm lines 66–76 at 68aec5c · upstream ↗ 2126 LDA BATTLERS_TABLE+battler::consciousness,Y 2127 AND #$00FF 2128 BEQ @UNKNOWN149 2129 LDA BATTLERS_TABLE+13,Y 2130 AND #$00FF 2131 BNE @UNKNOWN149 2132 LDA BATTLERS_TABLE+70,Y 2133 TAY 2134 STX @VIRTUAL02 2135 TYA 2136.ENDIF 2137 CMP @VIRTUAL02 ⋮
src/battle/main_battle_routine.asm lines 2126–2138 at 68aec5c · upstream ↗ Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
- ^In EarthBound (US release), running away never works against a boss. Otherwise it works on the first turn of a battle the party started with the first strike, or when no enemy can act; else it works with a chance of about (10 × the turn number + the fastest party member's Speed − the fastest able enemy's Speed) in 100, and never when that is below 0.CodeHerringway/ebsrc
How we know
1276 LDA @LOCAL07 1277 CMP #BATTLE_ACTIONS::RUN_AWAY ⋮ 1286 CMP #1 1287 BNE @UNKNOWN85 1288 LDA #4 ⋮ 1295@UNKNOWN85: 1296 LDA #3
src/battle/main_battle_routine.asm lines 1276–1300 at 68aec5c · upstream ↗ 1950@UNKNOWN136: 1951 LDA a:battler::consciousness,Y 1952 AND #$00FF 1953 BEQ @UNKNOWN139 1954 LDA a:battler::npc_id,Y 1955 AND #$00FF 1956 BNE @UNKNOWN139 1957 LDA a:battler::ally_or_enemy,Y 1958 AND #$00FF 1959 CMP #1 1960 BNE @UNKNOWN138 ⋮ 1965 ADC #enemy_data::boss ⋮
src/battle/main_battle_routine.asm lines 1950–1969 at 68aec5c · upstream ↗ 1999@UNKNOWN138: 2000 LDA a:battler::speed,Y 2001 CMP @LOCAL05 2002 BLTEQ @UNKNOWN139 2003 STA @LOCAL05
src/battle/main_battle_routine.asm lines 1999–2003 at 68aec5c · upstream ↗ 2019 LDA @VIRTUAL04 2020 BEQ @UNKNOWN142 ⋮ 2024 LDA @LOCAL06 2025.ENDIF 2026 CMP #4 2027 BEQ @UNKNOWN142 ⋮ 2031 LDA @LOCAL0A 2032.ENDIF 2033 OPTIMIZED_MULT @VIRTUAL04, 10 2034 CLC 2035 ADC @LOCAL05 ⋮ 2041.ENDIF ⋮
src/battle/main_battle_routine.asm lines 2019–2068 at 68aec5c · upstream ↗ 1113.ELSE 1114 INC @LOCAL0A 1115.ENDIF
src/battle/main_battle_routine.asm lines 1112–1116 at 68aec5c · upstream ↗ Checked against the evidence by its author, an AI model, 2026-10-21.
Checked by a second AI model, 2026-10-21.
Sources
Code
- Herringway. 2026. “ebsrc: Source code recreation for the game Earthbound.” Commit 68aec5c. Herringway/ebsrc @ 68aec5c · licence, all uses
- n.d. “EarthBound (USA).” · licence, all uses
- Nathan-R-Og. 2026. “mother: Disassembly of Mother/Earthbound Zero/Earthbound Beginnings for the NES.” Commit e0b3e3f. Nathan-R-Og/mother @ e0b3e3f · licence, all uses