Active Time Battle

References

1. ^ abAt the start of a battle, each combatant's base timer duration is 50 times a reference party member's modified agility over 10 times its own modified agility, at least 1; the reference is the first present party member whose character ID is 1 or $0B, or failing that the first present one, so a combatant with twice the agility waits half as long between turns.Codeeverything8215, FF4 disassembly
   How we know

   493@8d44:  clr_axy
   494        stx     $c7
   495@8d49:  lda     $3540,y
   496        bne     @8d5f
   497        lda     $c7
   498        bne     @8d7a
   499        lda     $2000,x
   500        and     #$1f
   501        cmp     #$01
   502        beq     @8d7a
   503        cmp     #$0b
   

   518@8d7a:  lda     $2015,x
   ⋮
   521        ldx     #$0032
   522        stx     $393f
   523        jsr     Mult16
   ⋮
   533        lda     $2015,x
   534        sta     $df
   535        lda     #$0a
   536        sta     $e1
   537        jsr     Mult8
   ⋮
   542        jsr     Div16
   543        ldx     $3949
   544        bne     @8dbf
   ⋮
   

   $1015 modified agility

   Checked against the evidence by its author, an AI model, 2026-10-21.

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

   In the claim ledger

2. ^ abBattleMain waits 1, 2, 4, 6, 8, or 11 frames by the battle speed setting (BattleSpeedTbl plus one), holding while the game is paused or in wait mode, then decrements every combatant's timers (DecTimers) and runs a pending action. An action timer's duration is the base duration times a speed modifier over 16, and 16 is the normal modifier.Codeeverything8215, FF4 disassembly
   How we know

   1021BattleMain:
   1022@85d9:  lda     $16ac                   ; battle speed
   1023        tax
   1024        lda     f:BattleSpeedTbl,x
   1025        inc
   1026        sta     $3538
   1027        stz     $38e6
   1028@85e8:  lda     #$02                    ; battle graphics $02: wait one frame
   1029        jsr     ExecBtlGfx
   1030        lda     $38d9
   1031        ora     $38da
   1032        bne     @85e8                   ; branch if paused or wait mode
   ⋮
   

   1067@8649:  jsr     DecTimers
   ⋮
   1081@866d:  jsr     GetPendingAction
   ⋮
   1085        jsr     DoAction
   

   1476; not stopped
   1477@96d6:  inx3                ; next timer
   1478        lda     #6          ; loop through 6 timers
   ⋮
   1504        dec     $2a04,x     ; decrement counter
   

   367; battle speed constants
   368BattleSpeedTbl:
   369@ff06:  .byte   0,1,3,5,7,10
   

   282ApplySpeedMod:
   283@9fd8:  ldx     $a9         ; base duration
   284        stx     $393d
   285        ldx     $3979       ; multiplier
   286        stx     $393f
   287        jsr     Mult16
   ⋮
   290        ldx     #$0010
   291        stx     $3947
   292        jsr     Div16
   293        ldx     $3949
   294        stx     $ab         ; mod. duration
   

   898        lda     #$01        ; auto-battle speed modifier
   899        sta     $203b,x
   900        bra     @9086
   901@9081:  lda     #$10        ; normal speed modifier
   902        sta     $203b,x
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

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

   In the claim ledger

3. ^ abFinal Fantasy IV and V both give each combatant a timer that counts down to its turn. Final Fantasy IV sets its length from a ratio, 50 times a reference party member's agility over 10 times the combatant's; Final Fantasy V sets it to 120 plus equipment weight ÷ 8 minus agility.Codeeverything8215, FF4 disassembly · everything8215, FF5 disassembly
   How we know

   521        ldx     #$0032
   ⋮
   535        lda     #$0a
   ⋮
   542        jsr     Div16
   ⋮
   548        sta     $2060,x
   

   1477@96d6:  inx3                ; next timer
   1478        lda     #6          ; loop through 6 timers
   ⋮
   1504        dec     $2a04,x     ; decrement counter
   

   5407        jsr ShiftDivide_8	;weight/8
   5408        clc
   5409        adc #$78     		;+120
   5410        sec
   5411        sbc Agility    	;-agi
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

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

   In the claim ledger

4. ^ abFinal Fantasy V counts each combatant's ATB timer down by one per tick from 120 + weight ÷ 8 − agility; Final Fantasy VI instead adds a constant built from speed to a gauge every 2 frames and gives the turn when the gauge overflows.Codeeverything8215, FF5 disassembly · everything8215, FF6 disassembly
   How we know

   5409        adc #$78     		;+120
   5410        sec
   5411        sbc Agility    	;-agi
   

   4740        lda CurrentTimer,X
   ⋮
   4742        dec CurrentTimer,X
   4743        lda CurrentTimer,X
   4744        bne TimerActive
   4745FlagTimer:        	;flag EnableTimer when CurrentTimer hits 0
   

   91; [ increment atb gauge counter ]
   ⋮
   98        adc     near wTargetProp2::w7e3ac8,x     ; add atb constant
   99        sta     near wTargetProp1::w7e3218,x
   100        shorta
   101        bcc     _11ba       ; return if it didn't overflow
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

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

   In the claim ledger

5. ^A combatant's ATB timer is set to 120 + equipment weight ÷ 8 − agility, at least 1, adjusted for haste or slow, and UpdateTimer counts it down by one each tick and flags it when it reaches 0, when the turn comes due. The battle speed setting sets a wait of 0, 15, 30, 60, 120, or 240 when a character's turn arrives.Codeeverything8215, FF5 disassembly
   How we know

   5397;initialize ATB (A: character index 0-12)
   5398.proc ResetATB
   ⋮
   5406        lda CharStruct::EqWeight,X
   5407        jsr ShiftDivide_8	;weight/8
   5408        clc
   5409        adc #$78     		;+120
   5410        sec
   5411        sbc Agility    	;-agi
   5412        beq :+
   5413        bcs :++
   5414:       lda #$01     		;min 1
   5415:       jsr HasteSlowMod
   ⋮
   

   4721;Advances a status/atb timer if that status is supposed to be checked this tick
   ⋮
   4725.proc UpdateTimer
   ⋮
   4740        lda CurrentTimer,X
   4741        beq FlagTimer
   4742        dec CurrentTimer,X
   4743        lda CurrentTimer,X
   4744        bne TimerActive
   4745FlagTimer:        	;flag EnableTimer when CurrentTimer hits 0
   

   11470        and #$0F		;battle mode and speed
   11471        tax
   11472        lda f:BattleSpeedTbl,X
   11473        sta ATBWaitTime
   

   5336;Waits when a character's turn arrives (amount depending on battle speed setting)
   5337.proc ATBWait
   ⋮
   5342        lda ATBWaitLeft
   5343        beq DoneWaiting
   5344        dec
   5345        sta ATBWaitLeft
   

   24789; d0/ecf2: battle speed constants
   24790BattleSpeedTbl:
   24791        .byte   0,15,30,60,120,240,0,0  ; active
   24792        .byte   0,15,30,60,120,240,0,0  ; wait
   

   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

6. ^Each combatant's ATB gauge constant is (speed + 20) times 1.5 times a haste, normal, or slow constant of 84, 64, or 32, over 16; for monsters the speed term is first scaled by 255 − 24 × the battle speed setting, over 255, so the setting slows only the monsters. Every 2 frames UpdateBattleTime adds each present combatant's constant to its gauge, and a gauge that overflows gives that combatant a turn. It skips the update only when wait mode is on and the battle-time-stopped flag is also set, since it ANDs the two.Codeeverything8215, FF6 disassemblyrevised
   How we know

   1437; [ update atb gauge constant ]
   ⋮
   1439CalcSpeed:
   1440@09d2:  php
   1441        ldy     #$20
   1442        lda     near wTargetProp3::w7e3ef8,x
   1443        bit     #STATUS3::SLOW
   1444        bne     @09e4
   1445        ldy     #$40        ; y = haste/normal/slow constant (32/64/82)
   1446        bit     #STATUS3::HASTE
   1447        beq     @09e4
   1448        ldy     #$54
   ⋮
   1454        lsr
   ⋮
   

   4; [ update battle time ]
   ⋮
   6UpdateBattleTime:
   ⋮
   10        lda     near w7e2f41       ; check if battle time is stopped by battle program
   11        and     near w7e3a8f       ; wait mode
   12        bne     @118b
   13        lda     near w7e3a6c       ; previous frame counter value
   14        ldx     #2
   15@112e:  cmp     $0e         ; current frame counter value
   16        beq     @1190       ; return if less than 2 frames have elapsed
   

   91; [ increment atb gauge counter ]
   ⋮
   97        lda     near wTargetProp1::w7e3218,x     ; atb gauge %
   98        adc     near wTargetProp2::w7e3ac8,x     ; add atb constant
   99        sta     near wTargetProp1::w7e3218,x
   100        shorta
   101        bcc     _11ba       ; return if it didn't overflow
   ⋮
   105@11d1:  stz     near wTargetProp1::w7e3218_H,x     ; clear atb gauge %
   ⋮
   116        jsr     SetFlag0     ; set $3aa0.7 (allow battle menu to open)
   ⋮
   121; [ open battle menu (character) or add action to advance wait queue (monster) ]
   ⋮
   149_120e:  jmp     _c24e66       ; add action to advance wait queue
   

   75@2481:  and     #$07        ; battle speed
   76        asl3
   77        sta     $ee
   78        asl
   79        adc     $ee
   80        not_a
   81        sta     near w7e3a90       ; set battle speed constant
   

   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 the claim ledger

7. ^Square's United States patent on "active time battle", in which enemies keep acting on their own timers while the player enters commands, names Hironobu Sakaguchi and Hiroyuki Itou as inventors. It was filed on 16 March 1992 and granted on 21 February 1995; Google Patents gives its priority date as 16 July 1991, from Japanese application 3-199828.PublisherUS patent 5,390,937 (Active Time Battle)
   How we know

   The movements of the player character and enemy character, i.e., their actions in combat, are executed repeatedly without interruption while time is passing at a fixed rate. This shall be referred to as "active time battle".

   an enemy character on a display screen may launch an attack against a player character on the same screen, even while the player character is in the process of inputting a command, at elapse of a set time period specific to the enemy character.

   Inventor Hironobu Sakaguchi Hiroyuki Itou … Filing date 1992-03-16 Publication date 1995-02-21

   JP3-199828

   The quote matches our archived copy.

   Checked by a second AI model, 2026-10-23.

   In the claim ledger

8. ^Takashi Tokita told 1UP that the idea of Active Time Battle came from the planner Hiroyuki Ito, who was watching a Formula One race and saw the cars overtake one another: from that came characters whose speed differs by type. Tokita said it also let the team build enemies like those of shooting and action games, which change shape or fight as a wall closes in.Interview1UP, Tokita on FFIV
   How we know

   The planner, Hiroyuki Itoh, who directed Final Fantasy XII, was watching a Formula One race, and he saw all the cars surpass each other. From this, we thought of an interesting idea where character speed would differ depending on the type of character it was. That's where the initial idea came from.

   So, like in shooting and action games, there are instances where the enemies will change shape, or fight as a wall is closing in on them -- that was a new kind of enemy structure we were able to implement.

   The quote matches our archived copy.

   Checked by a second AI model, 2026-10-23.

   In the claim ledger

9. ^Hironobu Sakaguchi, in Square Enix's 2023 anniversary interview as transcribed by Nova Crystallis, said he thought it was Hiroyuki Ito who came up with Active Time Battle, because the move to the Super Famicom called for something special. The prototype wasn't fun, he said, and the programmer Kiyoshi Yoshii refined the system until it was in good shape.InterviewNova Crystallis, FF 35th anniversary interview, part 2
   How we know

   I think it was Hiroyuki Ito. We always try to do something new with the battle system, not just with the story and the setting. With the move to the Super Famicom for FFIV, we felt we really had to do something special, so he came up with ATB (Active Time Battle). The prototype was no good.

   When we programmed a test, it just wasn't fun. The programmer was a guy called Yoshii

   But he concentrated really hard and refined the system. And it was in good shape by the end.

   The quote matches our archived copy.

   Checked by a second AI model, 2026-10-23.

   In the claim ledger

10. ^Time always flows in battle: a player who doesn't act is attacked by the enemy regardless, and some enemies transform as time passes. Nintendo's page says the system, a standard of later Final Fantasy games, was used first in this game, and Square Enix's that Active Time Battle appeared from this game on.PublisherNintendo, VC Final Fantasy IV · Square Enix, FFIV official page
    How we know

    バトル中はつねに時間が流れており、こちらが行動しないと敵から一方的に攻められてしまいます。また、時間の経過とともに変身する敵がいるなど、さまざまなことが起こります。 … のちの『FF』シリーズで定番となるこのシステムは、このゲームで最初に使われました。

    今作からバトル中も時間が流れる「アクティブタイムバトル」が登場しました。

    The quote matches our archived copy.

    Checked by a second AI model, 2026-10-23.

    In the claim ledger