Welcome to Data Crystal's new home! Data Crystal is now part of the TCRF family (sort of).
The wiki has recently moved; please report any issues in Discord. Pardon the dust.
The wiki has recently moved; please report any issues in Discord. Pardon the dust.
The Little Mermaid/ROM map
< The Little Mermaid(Redirected from The Little Mermaid:ROM map)
Jump to navigation
Jump to search
The following article is a ROM map for The Little Mermaid.
Page 06 (0x8000-0xBFFF)
Address in ROM: 0x18010-0x1C00F
Function 0x8000
Runs the action scripts of every object slot from lowest to highest and checks for collisions each frame.
06:8000:A5 B1 LDA $00B1 ; Check Ariel's health 06:8002:F0 3A BEQ $803E ; Exit if zero 06:8004:A2 01 LDX #$01 06:8006:86 EF STX $00EF ; Current slot # 06:8008:A9 06 LDA #$06 06:800A:85 99 STA $0099 ; ? 06:800C:BD 00 03 LDA $0300,X 06:800F:10 25 BPL $8036 ; Skip ahead if slot is empty 06:8011:BD A0 04 LDA $04A0,X ; Check if object is stunned 06:8014:D0 16 BNE $802C ; If so, skip action script 06:8016:BC 10 03 LDY $0310,X 06:8019:B9 20 85 LDA $8520,Y ; Obtain address of action script 06:801C:85 00 STA $0000 ; from jump table 06:801E:B9 80 85 LDA $8580,Y ; 06:8021:85 01 STA $0001 06:8023:A9 80 LDA #$80 ; Set return address 06:8025:48 PHA 06:8026:A9 2B LDA #$2B 06:8028:48 PHA 06:8029:6C 00 00 JMP ($0000) ; Run object's action script 06:802C:E0 03 CPX #$03 ; Check if object is a bubble 06:802E:90 06 BCC $8036 ; Jump ahead if so 06:8030:20 3F 80 JSR $803F ; Test collision with Ariel 06:8033:20 FF 80 JSR $80FF ; Test collision with bubble 06:8036:E6 EF INC $00EF ; Tick up to next object slot 06:8038:A6 EF LDX $00EF 06:803A:E0 10 CPX #$10 ; Loop until all slots examined 06:803C:D0 CA BNE $8008 06:803E:60 RTS -----------------------------------------
Function 0x803F
Checks if Ariel is colliding with object X and performs appropriate action if so.
06:803F:20 F2 FA JSR $FAF2 ; Check if Ariel is colliding with object X 06:8042:B0 79 BCS $80BD ; Exit if not 06:8044:BD C0 03 LDA $03C0,X ; Check if item has damage flag 06:8047:29 40 AND #$40 ; 06:8049:F0 73 BEQ $80BE ; Skip to next section if not ARIEL COLLIDES WITH DAMAGING OBJECT 06:804B:A5 3F LDA $003F 06:804D:05 2F ORA $002F 06:804F:D0 6C BNE $80BD ; Exit unless both are zero 06:8051:A5 BB LDA $00BB 06:8053:D0 68 BNE $80BD ; Exit if not zero 06:8055:A9 07 LDA #$07 06:8057:C5 30 CMP $0030 06:8059:F0 62 BEQ $80BD ; Exit if Ariel is already in damage animation ARIEL TAKES DAMAGE 06:805B:C6 B1 DEC $00B1 ; Tick down health 06:805D:D0 05 BNE $8064 ; Jump ahead if not zero 06:805F:A0 00 LDY #$00 06:8061:8C 80 04 STY $0480 ; Clear Parameter 3 06:8064:A4 30 LDY $0030 06:8066:8C 60 04 STY $0460 ; Preserve Ariel's previous action phase 06:8069:85 30 STA $0030 ; Set damage animation 06:806B:A9 1D LDA #$1D 06:806D:20 A0 FC JSR $FCA0 06:8070:C0 04 CPY #$04 06:8072:F0 27 BEQ $809B 06:8074:C0 05 CPY #$05 06:8076:F0 23 BEQ $809B 06:8078:A9 08 LDA #$08 06:807A:8D 30 04 STA $0430 06:807D:A9 00 LDA #$00 06:807F:8D 18 04 STA $0418 06:8082:8D 48 04 STA $0448 06:8085:8D 60 04 STA $0460 06:8088:C0 02 CPY #$02 06:808A:D0 0F BNE $809B 06:808C:8C 60 04 STY $0460 06:808F:AC B0 03 LDY $03B0 06:8092:30 29 BMI $80BD 06:8094:8D A0 03 STA $03A0 06:8097:8D B0 03 STA $03B0 06:809A:60 RTS ----------------------------------------- 06:809B:A9 00 LDA #$00 06:809D:85 3A STA $003A 06:809F:8D 80 03 STA $0380 06:80A2:A9 01 LDA #$01 06:80A4:8D 90 03 STA $0390 06:80A7:A9 10 LDA #$10 06:80A9:8D 70 04 STA $0470 06:80AC:A9 01 LDA #$01 06:80AE:8D D0 03 STA $03D0 06:80B1:AD 00 04 LDA $0400 06:80B4:29 40 AND #$40 06:80B6:F0 21 BEQ $80D9 06:80B8:A9 02 LDA #$02 06:80BA:8D D0 03 STA $03D0 06:80BD:60 RTS ----------------------------------------- ARIEL COLLIDES WITH CARRYABLE OBJECT 06:80BE:A5 3A LDA $003A 06:80C0:05 30 ORA $0030 06:80C2:D0 15 BNE $80D9 06:80C4:BD 10 03 LDA $0310,X 06:80C7:C9 30 CMP #$30 ; Check if object is shell 06:80C9:F0 0C BEQ $80D7 ; If so, set as carried object 06:80CB:C9 02 CMP #$02 ; Check if object is bubble 06:80CD:D0 0A BNE $80D9 ; If not, exit 06:80CF:86 3A STX $003A ; Set bubble as carried object 06:80D1:A9 00 LDA #$00 06:80D3:9D 80 04 STA $0480,X ; Set bubble's parameter 3 as zero 06:80D6:60 RTS ----------------------------------------- 06:80D7:86 3A STX $003A 06:80D9:60 RTS -----------------------------------------
Function 0x81C4
06:81C4:86 04 STX $0004 ; Temp storage for current object slot 06:81C6:BD 00 04 LDA $0400,X ; Object orientation 06:81C9:30 03 BMI $81CE 06:81CB:4C 84 82 JMP $8284 06:81CE:A9 00 LDA #$00 06:81D0:85 07 STA $0007 06:81D2:BD C0 03 LDA $03C0,X ; 06:81D5:29 1F AND #$1F 06:81D7:C9 02 CMP #$02 06:81D9:F0 04 BEQ $81DF 06:81DB:C9 03 CMP #$03 06:81DD:D0 04 BNE $81E3 06:81DF:A9 08 LDA #$08 06:81E1:85 07 STA $0007 06:81E3:A0 0F LDY #$0F 06:81E5:BD 60 03 LDA $0360,X ; Object y-position low byte 06:81E8:38 SEC 06:81E9:E5 FA SBC $00FA 06:81EB:B0 03 BCS $81F0 06:81ED:E9 0F SBC #$0F 06:81EF:18 CLC 06:81F0:85 05 STA $0005 06:81F2:BD 70 03 LDA $0370,X ; Object y-position high byte 06:81F5:E5 FB SBC $00FB 06:81F7:29 01 AND #$01 06:81F9:F0 03 BEQ $81FE 06:81FB:4C 84 82 JMP $8284 06:81FE:C4 04 CPY $0004 06:8200:F0 7A BEQ $827C 06:8202:B9 00 03 LDA $0300,Y 06:8205:10 75 BPL $827C 06:8207:B9 00 04 LDA $0400,Y 06:820A:10 70 BPL $827C 06:820C:29 04 AND #$04 06:820E:D0 6C BNE $827C 06:8210:B9 C0 03 LDA $03C0,Y 06:8213:29 40 AND #$40 06:8215:F0 65 BEQ $827C 06:8217:BE 10 03 LDX $0310,Y 06:821A:BD C0 84 LDA $84C0,X 06:821D:F0 5D BEQ $827C 06:821F:B9 A0 04 LDA $04A0,Y 06:8222:D0 58 BNE $827C 06:8224:B9 C0 03 LDA $03C0,Y 06:8227:29 1F AND #$1F 06:8229:AA TAX 06:822A:BD 80 FB LDA $FB80,X 06:822D:18 CLC 06:822E:65 07 ADC $0007 06:8230:85 02 STA $0002 06:8232:C6 02 DEC $0002 06:8234:BD 60 FB LDA $FB60,X 06:8237:18 CLC 06:8238:65 07 ADC $0007 06:823A:85 03 STA $0003 06:823C:A6 04 LDX $0004 06:823E:B9 30 03 LDA $0330,Y 06:8241:38 SEC 06:8242:FD 30 03 SBC $0330,X 06:8245:48 PHA 06:8246:B9 40 03 LDA $0340,Y 06:8249:FD 40 03 SBC $0340,X 06:824C:68 PLA 06:824D:B0 04 BCS $8253 06:824F:49 FF EOR #$FF 06:8251:69 01 ADC #$01 06:8253:C5 02 CMP $0002 06:8255:B0 25 BCS $827C 06:8257:B9 60 03 LDA $0360,Y 06:825A:38 SEC 06:825B:E5 FA SBC $00FA 06:825D:B0 03 BCS $8262 06:825F:E9 0F SBC #$0F 06:8261:18 CLC 06:8262:85 1F STA $001F 06:8264:B9 70 03 LDA $0370,Y 06:8267:E5 FB SBC $00FB 06:8269:29 01 AND #$01 06:826B:D0 0F BNE $827C 06:826D:A5 1F LDA $001F 06:826F:38 SEC 06:8270:E5 05 SBC $0005 06:8272:B0 04 BCS $8278 06:8274:49 FF EOR #$FF 06:8276:69 01 ADC #$01 06:8278:C5 03 CMP $0003 06:827A:90 12 BCC $828E 06:827C:88 DEY 06:827D:C0 02 CPY #$02 06:827F:F0 03 BEQ $8284 06:8281:4C FE 81 JMP $81FE 06:8284:A6 04 LDX $0004 06:8286:38 SEC 06:8287:60 RTS -----------------------------------------
Data Table 0x8520
Jump table for object action functions
| Action # | Address | Description |
| 0x00 | 0x85E0 | Blank (used for Ariel) |
| 0x01 | 0x85E1 | Thrown objects |
| 0x02 | 0x888F | Enemy in bubble |
| 0x03 | 0x8A14 | Fish, Type 1 |
| 0x04 | 0x867A | |
| 0x05 | 0x8A65 | Seahorse |
| 0x06 | 0x8A9B | |
| 0x07 | 0x8BDC | |
| 0x08 | 0x8BE2 | Spitting fish |
| 0x09 | 0x8CA3 | |
| 0x0A | 0x8CBA | Octopus |
| 0x0B | 0x8DC5 | Octopus' rock |
| 0x0C | 0x9BA7 | Stage 1 Boss (Shark): Sending Fish |
| 0x0D | 0x9CC4 | Stage 1 Boss (Shark): Dashing |
| 0x0E | 0x9D37 | Fish (Stage 1 Boss fight) |
| 0x0F | 0xA3B3 | Cannon (Stage 4 Boss fight) |
| 0x10 | 0x8F89 | |
| 0x11 | 0x8FC7 | |
| 0x12 | 0x9046 | Fish, Type 2 |
| 0x13 | 0xAF50 | |
| 0x14 | 0xAF50 | |
| 0x15 | 0x908F | Crab (Stage 2 Boss fight) |
| 0x16 | 0x91D9 | Tiny fish (following Ariel) |
| 0x17 | 0x913F | |
| 0x18 | 0x913F | |
| 0x19 | 0x913F | |
| 0x1A | 0x913F | |
| 0x1B | 0x913F | |
| 0x1C | 0x92A9 | Sleeper fish |
| 0x1D | 0x9229 | Tiny fish (default action) |
| 0x1E | 0x9367 | |
| 0x1F | 0x9274 | Tiny fish (quad pattern) |
| 0x20 | 0x940C | Shrimp |
| 0x21 | 0x9460 | Poor Unfortunate Soul (Stage 5) |
| 0x22 | 0x9461 | Starfish spawner |
| 0x23 | 0x954F | Starfish (shooting upward) |
| 0x24 | 0x9604 | Frozen fish |
| 0x25 | 0x908F | Helmet crab |
| 0x26 | 0x869D | Crab (walking) |
| 0x27 | 0x86C1 | Crab (ducking/falling) |
| 0x28 | 0x86F1 | |
| 0x29 | 0x8715 | |
| 0x2A | 0x9D3A | Stage 3 Boss (Walrus): Default |
| 0x2B | 0x9EC7 | Stage 3 Boss (Walrus): Dropping item |
| 0x2C | 0x9F60 | Stage 2 Boss (Eel) #1 |
| 0x2D | 0x9F60 | Stage 2 Boss (Eel) #2 |
| 0x2E | 0xA1CF | Stage 4 Boss (Seahorse) |
| 0x2F | 0xA324 | Fish (Stage 4 Boss fight) |
| 0x30 | 0x986D | Carried item |
| 0x31 | 0x97D5 | |
| 0x32 | 0x97D5 | |
| 0x33 | 0x97D5 | |
| 0x34 | 0x9A36 | |
| 0x35 | 0x9A36 | |
| 0x36 | 0x9A11 | |
| 0x37 | 0x87EE | |
| 0x38 | 0x998B | Red Orb |
| 0x39 | 0x998B | Green Orb |
| 0x3A | 0x9A69 | |
| 0x3B | 0x9A69 | |
| 0x3C | 0x8DCB | Volcano |
| 0x3D | 0x878B | |
| 0x3E | 0xA63D | |
| 0x3F | 0x888E | |
| 0x40 | 0x888E | Water splash |
| 0x41 | 0x8EE3 | |
| 0x42 | 0x877D | End-of-stage jar |
| 0x43 | 0x8DCB | Upside-down volcano |
| 0x44 | 0x8E8C | Volcanic rock |
| 0x45 | 0x9654 | |
| 0x46 | 0x96E1 | |
| 0x47 | 0xA3D9 | Stage 5 Boss (Ursula 1) |
| 0x48 | 0xA54F | Enemy Spawn 1 (Stage 5 Boss fight) |
| 0x49 | 0xA5F0 | Enemy Spawn 2 (Stage 5 Boss fight) |
| 0x4A | 0xA5F6 | Orb (Stage 5 Boss fight) |
| 0x4B | 0x8F6E | |
| 0x4C | 0x876B | |
| 0x4D | 0x9AA1 | Hidden item (?) |
| 0x4E | 0x9AA1 | Hidden item (?) |
| 0x4F | 0x9AA1 | Hidden item (?) |
| 0x50 | 0x9AA1 | Hidden item (?) |
| 0x51 | 0x9AA1 | Hidden item (?) |
| 0x52 | 0x9B0A | Flounder |
| 0x53 | 0x9B0A | |
| 0x54 | 0x9B0A | |
| 0x55 | 0x9B0A | |
| 0x56 | 0x9B0A | |
| 0x57 | 0xA692 | Stage 6 Boss (Ursula 2) |
| 0x58 | 0xA83E | Fish (Stage 6 Boss fight) |
| 0x59 | 0xA879 | |
| 0x5A | 0xA0D8 | Crab spawner (Stage 2 Boss fight) |
| 0x5B | 0xA324 | |
| 0x5C | 0x8821 | |
| 0x5D | 0x8872 | |
| 0x5E | 0x887F | |
| 0x5F | 0x888E | Urchin (Stage 4 Boss fight) |
Function 0x85E0
Action script 0x00 - Ariel
06:85E0:60 RTS -----------------------------------------
Function 0x85E1
Action script 0x01 - Thrown objects
06:85E1:20 C4 81 JSR $81C4 06:85E4:B0 0A BCS $85F0 06:85E6:BD 30 04 LDA $0430,X ; Animation loop 06:85E9:C9 40 CMP #$40 ; Check if shell 06:85EB:D0 F3 BNE $85E0 06:85ED:4C 47 86 JMP $8647 ; Function that handles thrown shell 06:85F0:20 35 D5 JSR $D535 06:85F3:B0 06 BCS $85FB 06:85F5:A9 00 LDA #$00 06:85F7:9D 00 03 STA $0300,X 06:85FA:60 RTS ----------------------------------------- 06:85FB:BD 30 04 LDA $0430,X 06:85FE:C9 40 CMP #$40 06:8600:F0 1D BEQ $861F 06:8602:A0 08 LDY #$08 06:8604:20 B9 FC JSR $FCB9 06:8607:B0 0E BCS $8617 06:8609:A0 06 LDY #$06 06:860B:20 CC FC JSR $FCCC 06:860E:A5 10 LDA $0010 06:8610:F0 05 BEQ $8617 06:8612:B0 03 BCS $8617 06:8614:4C 4E 98 JMP $984E 06:8617:20 71 83 JSR $8371 06:861A:A9 1B LDA #$1B 06:861C:4C A0 FC JMP $FCA0 06:861F:A0 08 LDY #$08 06:8621:20 B9 FC JSR $FCB9 06:8624:20 4E 98 JSR $984E 06:8627:90 13 BCC $863C 06:8629:A5 BE LDA $00BE 06:862B:C9 30 CMP #$30 06:862D:D0 18 BNE $8647 06:862F:A5 1A LDA $001A 06:8631:D0 46 BNE $8679 06:8633:20 BA E7 JSR $E7BA 06:8636:20 64 FE JSR $FE64 06:8639:4C 47 86 JMP $8647 06:863C:A0 06 LDY #$06 06:863E:20 CC FC JSR $FCCC 06:8641:A5 10 LDA $0010 06:8643:F0 02 BEQ $8647 06:8645:90 32 BCC $8679 06:8647:BD D0 03 LDA $03D0,X 06:864A:29 08 AND #$08 06:864C:F0 14 BEQ $8662 06:864E:BD 60 03 LDA $0360,X 06:8651:38 SEC 06:8652:E5 FA SBC $00FA 06:8654:B0 02 BCS $8658 06:8656:E9 0F SBC #$0F 06:8658:C9 04 CMP #$04 06:865A:B0 06 BCS $8662 06:865C:A9 00 LDA #$00 06:865E:9D 00 03 STA $0300,X 06:8661:60 RTS ----------------------------------------- 06:8662:A9 04 LDA #$04 06:8664:9D D0 03 STA $03D0,X 06:8667:A9 00 LDA #$00 06:8669:9D A0 03 STA $03A0,X 06:866C:9D B0 03 STA $03B0,X 06:866F:A9 81 LDA #$81 06:8671:9D 00 03 STA $0300,X 06:8674:A9 30 LDA #$30 06:8676:9D 10 03 STA $0310,X 06:8679:60 RTS -----------------------------------------
Function 0x9BA7
Action script 0x0C - Stage 1 Boss (Shark): Sending Fish
06:9BA7:BD 00 03 LDA $0300,X ; 06:9BAA:29 0F AND #$0F ; Identify phase # of boss fight 06:9BAC:D0 1D BNE $9BCB ; Jump ahead if not Phase 0 PHASE 0 - Intro 06:9BAE:20 09 A6 JSR $A609 ; Boss intro 06:9BB1:90 3C BCC $9BEF ; Only advance if intro has ended 06:9BB3:20 DF FC JSR $FCDF ; Turn sprite the right direction & begin moving horizontally onto screen 06:9BB6:FE 70 04 INC $0470,X ; Tick up timer 06:9BB9:BD 70 04 LDA $0470,X ; 06:9BBC:C9 40 CMP #$40 ; Move left for 0x40 (64) frames 06:9BBE:D0 2F BNE $9BEF ; 06:9BC0:FE 00 03 INC $0300,X ; Advance to Phase 1 06:9BC3:A9 00 LDA #$00 ; 06:9BC5:9D 60 04 STA $0460,X ; Set timer 1 to zero 06:9BC8:9D 70 04 STA $0470,X ; Set timer 2 to zero PHASE 1 06:9BCB:BD 70 04 LDA $0470,X ; If timer 2 is zero, jump ahead 06:9BCE:F0 20 BEQ $9BF0 ; Else tick down 06:9BD0:DE 70 04 DEC $0470,X ; 06:9BD3:D0 1A BNE $9BEF ; Exit 06:9BD5:A9 02 LDA #$02 ; 06:9BD7:9D 90 03 STA $0390,X ; 06:9BDA:A9 00 LDA #$00 ; 06:9BDC:9D 80 03 STA $0380,X ; 06:9BDF:9D 60 04 STA $0460,X ; 06:9BE2:9D 90 04 STA $0490,X ; 06:9BE5:A9 0D LDA #$0D ; 06:9BE7:9D 10 03 STA $0310,X ; 06:9BEA:A9 5D LDA #$5D ; 06:9BEC:20 45 FC JSR $FC45 ; Change to action script 0x0D (Dashing) 06:9BEF:60 RTS ----------------------------------------- 06:9BF0:BD 00 03 LDA $0300,X 06:9BF3:29 0F AND #$0F 06:9BF5:C9 03 CMP #$03 06:9BF7:F0 48 BEQ $9C41 06:9BF9:20 12 FD JSR $FD12 ; Check distance on y-axis between Ariel and Shark 06:9BFC:C9 20 CMP #$20 06:9BFE:B0 1C BCS $9C1C ; Jump ahead if 0x20 (32) or more 06:9C00:BD 90 04 LDA $0490,X 06:9C03:D0 0A BNE $9C0F 06:9C05:A5 E4 LDA $00E4 06:9C07:65 E5 ADC $00E5 06:9C09:85 E5 STA $00E5 06:9C0B:29 01 AND #$01 ; RNG #$00-#$01 06:9C0D:D0 06 BNE $9C15 ; Spawn fish (50/50 chance) 06:9C0F:A9 A0 LDA #$A0 06:9C11:9D 70 04 STA $0470,X ; Set timer between spawning fish and advancing to Phase 2 06:9C14:60 RTS ----------------------------------------- 06:9C15:A9 83 LDA #$83 06:9C17:9D 00 03 STA $0300,X ; 06:9C1A:D0 0C BNE $9C28 06:9C1C:BD 00 03 LDA $0300,X 06:9C1F:29 0F AND #$0F 06:9C21:C9 01 CMP #$01 06:9C23:D0 1C BNE $9C41 06:9C25:FE 00 03 INC $0300,X 06:9C28:A9 20 LDA #$20 06:9C2A:9D 60 04 STA $0460,X 06:9C2D:A9 00 LDA #$00 06:9C2F:9D 90 04 STA $0490,X ; 06:9C32:A8 TAY 06:9C33:AD 60 03 LDA $0360 06:9C36:DD 60 03 CMP $0360,X 06:9C39:90 02 BCC $9C3D 06:9C3B:A0 03 LDY #$03 06:9C3D:98 TYA 06:9C3E:9D 80 04 STA $0480,X 06:9C41:DE 60 04 DEC $0460,X 06:9C44:D0 75 BNE $9CBB 06:9C46:20 54 FE JSR $FE54 06:9C49:B0 70 BCS $9CBB 06:9C4B:86 0F STX $000F ; Object # of slot 06:9C4D:A9 20 LDA #$20 06:9C4F:20 51 FC JSR $FC51 ; Spawn fish 06:9C52:BD 60 03 LDA $0360,X 06:9C55:99 60 03 STA $0360,Y ; Set y-pos (low byte) to same as shark 06:9C58:BD 70 03 LDA $0370,X 06:9C5B:99 70 03 STA $0370,Y ; Set y-pos (high byte) to same as shark 06:9C5E:BD 40 03 LDA $0340,X 06:9C61:99 40 03 STA $0340,Y ; Set x-pos (high byte) to same as shark 06:9C64:BD D0 03 LDA $03D0,X 06:9C67:99 D0 03 STA $03D0,Y ; Set direction of movement to same as shark 06:9C6A:29 01 AND #$01 06:9C6C:AA TAX 06:9C6D:BD BC 9C LDA $9CBC,X 06:9C70:99 30 03 STA $0330,Y ; Set proper x-pos (low byte) for that side of screen 06:9C73:A6 0F LDX $000F 06:9C75:BD 80 04 LDA $0480,X 06:9C78:AA TAX 06:9C79:B9 60 03 LDA $0360,Y 06:9C7C:18 CLC 06:9C7D:7D BE 9C ADC $$9CBE,X 06:9C80:99 60 03 STA $0360,Y 06:9C83:A6 0F LDX $000F 06:9C85:C9 08 CMP #$08 06:9C87:90 86 BCC $9C0F 06:9C89:C9 E8 CMP #$E8 06:9C8B:B0 82 BCS $9C0F 06:9C8D:A9 00 LDA #$00 06:9C8F:99 80 03 STA $0380,Y 06:9C92:A9 01 LDA #$01 06:9C94:99 90 03 STA $0390,Y ; Set x-speed to 0x100 (1 pixel/frame) 06:9C97:A9 60 LDA #$60 06:9C99:99 C0 03 STA $03C0,Y ; Set "hitbox" and "able to be bubbled" flags 06:9C9C:A9 01 LDA #$01 06:9C9E:99 F0 03 STA $03F0,Y ; Set HP to 1 06:9CA1:A9 0E LDA #$0E 06:9CA3:99 10 03 STA $0310,Y ; Set action loop to 0x0E 06:9CA6:A9 40 LDA #$40 06:9CA8:9D 60 04 STA $0460,X 06:9CAB:FE 80 04 INC $0480,X 06:9CAE:FE 90 04 INC $0490,X ; Tick up fish counter 06:9CB1:BD 90 04 LDA $0490,X 06:9CB4:C9 03 CMP #$03 ; Check if fish counter is at 3 06:9CB6:90 03 BCC $9CBB ; Exit if so 06:9CB8:4C 0F 9C JMP $9C0F ; Else, reset fish spawn timer and exit 06:9CBB:60 RTS -----------------------------------------
Data Table 0x9CBC
x-position of spawned fish
06:9CBC:FC ; Shark on right 06:9CBD:04 ; Shark on left
Data Table 0x9CBE
y-positions of fish relative to shark
06:9CBE:E0 06:9CBF:C0 06:9CC0:A0 06:9CC1:20 06:9CC2:40 06:9CC3:60
Function 0xA609
Intro to boss fights
Returns one of the following as a result:
- Carry set = intro has ended
- Carry clear = continue intro
06:A609:A5 D9 LDA $00D9 06:A60B:C9 08 CMP #$08 06:A60D:B0 1D BCS $A62C 06:A60F:A5 30 LDA $0030 06:A611:F0 04 BEQ $A617 06:A613:C9 04 CMP #$04 06:A615:D0 22 BNE $A639 ; Exit (wait to advance) 06:A617:A5 30 LDA $0030 06:A619:8D 70 04 STA $0470 ; Set Ariel's timer 2 06:A61C:A9 08 LDA #$08 06:A61E:85 30 STA $0030 06:A620:85 53 STA $0053 06:A622:20 9E FC JSR $FC9E 06:A625:A9 60 LDA #$60 06:A627:85 5F STA $005F 06:A629:8D 60 04 STA $0460 ; Set Ariel's subtimer 1 to #$60 06:A62C:A5 5F LDA $005F 06:A62E:F0 0B BEQ $A63B 06:A630:C6 5F DEC $005F 06:A632:D0 05 BNE $A639 06:A634:A9 00 LDA #$00 06:A636:9D 48 04 STA $0448,X 06:A639:18 CLC ; Exit (wait to advance) 06:A63A:60 RTS ----------------------------------------- 06:A63B:38 SEC ; Exit (advance to next section) 06:A63C:60 RTS -----------------------------------------
Page 07 (0xC000-0xFFFF)
Location in ROM: 0x1C010-0x2000F
Function 0xC250
Advance random number generator each frame
07:C250:A2 00 LDX #$00 07:C252:A0 04 LDY #$04 07:C254:B5 E4 LDA $E4,X 07:C256:29 02 AND #$02 07:C258:85 00 STA $0000 07:C25A:B5 E5 LDA $E5,X 07:C25C:29 02 AND #$02 07:C25E:45 00 EOR $0000 ; If 0x02 bits of 0xE4 and 0xE5 07:C260:18 CLC ; are the same, highest bit of 07:C261:F0 01 BEQ $C264 ; new RNG value will be zero. 07:C263:38 SEC ; Otherwise, it will be one. 07:C264:76 E4 ROR $E4,X ; Then shift all previous bits right. 07:C266:E8 INX 07:C267:88 DEY 07:C268:D0 FA BNE $C264 07:C26A:60 RTS -----------------------------------------
Function 0xF887
Moves object to the right a distance equal to its speed
07:F887:BD 20 03 LDA $0320,X 07:F88A:18 CLC 07:F88B:7D 80 03 ADC $0380,X 07:F88E:9D 20 03 STA $0320,X 07:F891:BD 30 03 LDA $0330,X 07:F894:7D 90 03 ADC $0390,X 07:F897:9D 30 03 STA $0330,X 07:F89A:90 08 BCC $F8A4 07:F89C:BD 40 03 LDA $0340,X 07:F89F:69 00 ADC #$00 07:F8A1:9D 40 03 STA $0340,X 07:F8A4:60 RTS -----------------------------------------
Function 0xF8A5
Moves object to the left a distance equal to its speed
07:F8A5:BD 20 03 LDA $0320,X 07:F8A8:38 SEC 07:F8A9:FD 80 03 SBC $0380,X 07:F8AC:9D 20 03 STA $0320,X 07:F8AF:BD 30 03 LDA $0330,X 07:F8B2:FD 90 03 SBC $0390,X 07:F8B5:9D 30 03 STA $0330,X 07:F8B8:B0 08 BCS $F8C2 07:F8BA:BD 40 03 LDA $0340,X 07:F8BD:E9 00 SBC #$00 07:F8BF:9D 40 03 STA $0340,X 07:F8C2:60 RTS -----------------------------------------
Function 0xFCDF
Turns object's sprite to match direction of movement, then moves in that direction
07:FCDF:BD D0 03 LDA $03D0,X 07:FCE2:29 03 AND #$03 ; Check horizontal movement 07:FCE4:F0 2B BEQ $FD11 ; Exit if none 07:FCE6:29 01 AND #$01 07:FCE8:F0 0B BEQ $FCF5 ; Jump ahead if left movement not flagged MOVING LEFT 07:FCEA:BD 00 04 LDA $0400,X 07:FCED:09 40 ORA #$40 07:FCEF:9D 00 04 STA $0400,X ; Set "flip sprite" flag 07:FCF2:4C 87 F8 JMP $F887 ; Move left MOVING RIGHT 07:FCF5:BD 00 04 LDA $0400,X 07:FCF8:29 BF AND #$BF 07:FCFA:9D 00 04 STA $0400,X ; Clear "flip sprite" flag 07:FCFD:4C A5 F8 JMP $F8A5 ; Move right
Function 0xFFC8
Set RAM bank 0x8000-0xBFFF to Page A
07:FFC8:AA TAX 07:FFC9:9D DE FF STA $FFDE,X 07:FFCC:60 RTS -----------------------------------------
Function 0xFFCD
Set RAM bank 0x8000-0xBFFF to Page A, retaining X/Y values
Store Page # to 0x9B/0x9C?
07:FFCD:85 9B STA $009B 07:FFCF:85 BF STA $00BF 07:FFD1:86 9C STX $009C 07:FFD3:84 9D STY $009D 07:FFD5:AA TAX 07:FFD6:9D DE FF STA $FFDE,X 07:FFD9:A6 9C LDX $009C 07:FFDB:A4 9D LDY $009D 07:FFDD:60 RTS -----------------------------------------
Data Table 0xFFDE
Used by functions 0xFFC8 and 0xFFCD for bank switching.
See here for more info.
07:FFDE:00 07:FFDF:01 07:FFE0:02 07:FFE1:03 07:FFE2:04 07:FFE3:05 07:FFE4:06
Internal Data for The Little Mermaid
| |
|---|---|