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Difference between revisions of "Add Spin Dash to Sonic 1/Part 3"

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m (Text replace - '[[Category:SCHG How-tos|' to '{{S1Howtos}} [[Category:SCHG How-tos|')
m (Added a comment to QueueDMATransfer on how to use it outside of the Spin Dash)
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; Can be called a maximum of 18 times before the buffer needs to be cleared
 
; Can be called a maximum of 18 times before the buffer needs to be cleared
 
; by issuing the commands (this subroutine DOES check for overflow)
 
; by issuing the commands (this subroutine DOES check for overflow)
 +
; ---------------------------------------------------------------------------
 +
; In case you wish to use this queue system outside of the spin dash, this is the
 +
; registers in which it expects data in:
 +
; d1.l: Address to data (In 68k address space)
 +
; d2.w: Destination in VRAM
 +
; d3.w: Length of data
 
; ---------------------------------------------------------------------------
 
; ---------------------------------------------------------------------------
  

Revision as of 16:53, 7 July 2012

(Original guide by shobiz)

While the end result of following Lightning's and Puto's guides is a near-perfect Spin Dash in Sonic 1, there are still a few things not right about it, so let's fix those.

Converting Sonic's art buffer to a DMA queue

This isn't exactly a bug per se, but the method used to port over the DMA queue to Sonic 1 in Puto's guide is slightly hack-ish. In stock Sonic 1, Sonic's sprites are copied over into a RAM buffer at $FFFFC800 before being DMAed to VRAM. This buffer occupies $300 bytes, so if we convert it to a DMA queue, besides getting a proper structure we also save $200 bytes of RAM (some of which will be used later on in this guide).

Firstly, let's modify the actual queue routines to use this RAM space. So go to DMA_68KtoVRAM and replace everything from there till the end of Process_DMA with:

<asm>; ---------------------------------------------------------------------------

Subroutine for queueing VDP commands (seems to only queue transfers to VRAM),
to be issued the next time ProcessDMAQueue is called.
Can be called a maximum of 18 times before the buffer needs to be cleared
by issuing the commands (this subroutine DOES check for overflow)
---------------------------------------------------------------------------
In case you wish to use this queue system outside of the spin dash, this is the
registers in which it expects data in
d1.l
Address to data (In 68k address space)
d2.w
Destination in VRAM
d3.w
Length of data
---------------------------------------------------------------------------
||||||||||||||| S U B R O U T I N E |||||||||||||||||||||||||||||||||||||||
sub_144E
DMA_68KtoVRAM: QueueCopyToVRAM: QueueVDPCommand: Add_To_DMA_Queue:

QueueDMATransfer: movea.l ($FFFFC8FC).w,a1 cmpa.w #$C8FC,a1 beq.s QueueDMATransfer_Done ; return if there's no more room in the buffer

; piece together some VDP commands and store them for later... move.w #$9300,d0 ; command to specify DMA transfer length & $00FF move.b d3,d0 move.w d0,(a1)+ ; store command

move.w #$9400,d0 ; command to specify DMA transfer length & $FF00 lsr.w #8,d3 move.b d3,d0 move.w d0,(a1)+ ; store command

move.w #$9500,d0 ; command to specify source address & $0001FE lsr.l #1,d1 move.b d1,d0 move.w d0,(a1)+ ; store command

move.w #$9600,d0 ; command to specify source address & $01FE00 lsr.l #8,d1 move.b d1,d0 move.w d0,(a1)+ ; store command

move.w #$9700,d0 ; command to specify source address & $FE0000 lsr.l #8,d1 move.b d1,d0 move.w d0,(a1)+ ; store command

andi.l #$FFFF,d2 ; command to specify destination address and begin DMA lsl.l #2,d2 lsr.w #2,d2 swap d2 ori.l #$40000080,d2 ; set bits to specify VRAM transfer move.l d2,(a1)+ ; store command

move.l a1,($FFFFC8FC).w ; set the next free slot address cmpa.w #$C8FC,a1 beq.s QueueDMATransfer_Done ; return if there's no more room in the buffer move.w #0,(a1) ; put a stop token at the end of the used part of the buffer

return_14AA

QueueDMATransfer_Done: rts

End of function QueueDMATransfer


---------------------------------------------------------------------------
Subroutine for issuing all VDP commands that were queued
(by earlier calls to QueueDMATransfer)
Resets the queue when it's done
---------------------------------------------------------------------------
||||||||||||||| S U B R O U T I N E |||||||||||||||||||||||||||||||||||||||
sub_14AC
CopyToVRAM: IssueVDPCommands: Process_DMA: Process_DMA_Queue:

ProcessDMAQueue: lea ($C00004).l,a5 lea ($FFFFC800).w,a1

loc_14B6

ProcessDMAQueue_Loop: move.w (a1)+,d0 beq.s ProcessDMAQueue_Done ; branch if we reached a stop token ; issue a set of VDP commands... move.w d0,(a5) ; transfer length move.w (a1)+,(a5) ; transfer length move.w (a1)+,(a5) ; source address move.w (a1)+,(a5) ; source address move.w (a1)+,(a5) ; source address move.w (a1)+,(a5) ; destination move.w (a1)+,(a5) ; destination cmpa.w #$C8FC,a1 bne.s ProcessDMAQueue_Loop ; loop if we haven't reached the end of the buffer

loc_14CE

ProcessDMAQueue_Done: move.w #0,($FFFFC800).w move.l #$FFFFC800,($FFFFC8FC).w rts

End of function ProcessDMAQueue</asm>

Next, let's modify Sonic's PLC routine to make use of this routine. Go to LoadSonicDynPLC and replace the entire routine with the Sonic 2 equivalent, slightly modified to make use of Sonic 1's PLC format:

<asm>LoadSonicDynPLC: ; XREF: Obj01_Control; et al moveq #0,d0 move.b $1A(a0),d0 ; load frame number cmp.b ($FFFFF766).w,d0 beq.s locret_13C96 move.b d0,($FFFFF766).w lea (SonicDynPLC).l,a2 add.w d0,d0 adda.w (a2,d0.w),a2 moveq #0,d5 move.b (a2)+,d5 subq.w #1,d5 bmi.s locret_13C96 move.w #$F000,d4 move.l #Art_Sonic,d6

SPLC_ReadEntry: moveq #0,d1 move.b (a2)+,d1 lsl.w #8,d1 move.b (a2)+,d1 move.w d1,d3 lsr.w #8,d3 andi.w #$F0,d3 addi.w #$10,d3 andi.w #$FFF,d1 lsl.l #5,d1 add.l d6,d1 move.w d4,d2 add.w d3,d4 add.w d3,d4 jsr (QueueDMATransfer).l dbf d5,SPLC_ReadEntry ; repeat for number of entries

locret_13C96: rts

End of function LoadSonicDynPLC</asm>

Third, we have to make the dust object use the new name for the DMA routine. Really simple, just go to loc_1DF0A and replace

<asm> jsr (DMA_68KtoVRAM).l</asm>

with

<asm> jsr (QueueDMATransfer).l</asm>

Finally, we have to make the game actually use these routines. Firstly, go to loc_CD4 and replace

<asm> tst.b ($FFFFF767).w beq.s loc_D50 lea ($C00004).l,a5 move.l #$94019370,(a5) move.l #$96E49500,(a5) move.w #$977F,(a5) move.w #$7000,(a5) move.w #$83,($FFFFF640).w move.w ($FFFFF640).w,(a5) move.b #0,($FFFFF767).w</asm>

with

<asm> jsr (ProcessDMAQueue).l</asm>

Make similar changes at loc_DAE, loc_EEE and loc_FAE. Secondly, go to loc_D50 and remove these two lines:

<asm> move #$83,($FFFFF640).w jsr Process_DMA</asm>

Thirdly, go to Level_ClrVars3 and after the

<asm> move.w #$8ADF,($FFFFF624).w move.w ($FFFFF624).w,(a6)</asm>

add

<asm> clr.w ($FFFFC800).w move.l #$FFFFC800,($FFFFC8FC).w</asm>

Finally, go to loc_47D4, and after

<asm> jsr Hud_Base</asm>

add

<asm> clr.w ($FFFFC800).w move.l #$FFFFC800,($FFFFC8FC).w</asm>

After this, the game will use the DMA queue for Sonic's art reloading, and we'll have $200 bytes of free RAM from $FFFFC900 to $FFFFCAFF.

Making the Spin Dash sound rev

This has always annoyed me a lot, but thanks to Xenowhirl's Sonic 2 sound driver disassembly and Tweaker's music guide, we can fix it. We need to use three RAM variables, so we can utilise our newly freed RAM. $FFFFC900 is a flag which is 1 if the Spin Dash sound was the last one played and 0 if it was not. $FFFFC901 is a timer, and $FFFFC902 is the pitch increase value.

First, go to loc_71BC8 and change it from

<asm>loc_71BC8: lea $40(a6),a5 tst.b (a5) bpl.s loc_71BD4 jsr sub_71C4E(pc)</asm>

to

<asm>loc_71BC8: tst.b ($FFFFC901).w beq.s @cont subq.b #1,($FFFFC901).w

@cont: lea $40(a6),a5 tst.b (a5) bpl.s loc_71BD4 jsr sub_71C4E(pc)</asm>

Then go to Sound_D1toDF and change if from

<asm>Sound_D1toDF: tst.b $27(a6) bne.w loc_722C6 tst.b 4(a6) bne.w loc_722C6 tst.b $24(a6) bne.w loc_722C6 movea.l (Go_SoundIndex).l,a0 sub.b #$A1,d7 bra SoundEffects_Common</asm>

to

<asm>Sound_D1toDF: tst.b $27(a6) bne.w loc_722C6 tst.b 4(a6) bne.w loc_722C6 tst.b $24(a6) bne.w loc_722C6 clr.b ($FFFFC900).w cmp.b #$D1,d7 ; is this the Spin Dash sound? bne.s @cont3 ; if not, branch move.w d0,-(sp) move.b ($FFFFC902).w,d0 ; store extra frequency tst.b ($FFFFC901).w ; is the Spin Dash timer active? bne.s @cont1 ; if it is, branch move.b #-1,d0 ; otherwise, reset frequency (becomes 0 on next line)

@cont1: addq.b #1,d0 cmp.b #$C,d0 ; has the limit been reached? bcc.s @cont2 ; if it has, branch move.b d0,($FFFFC902).w ; otherwise, set new frequency

@cont2: move.b #1,($FFFFC900).w ; set flag move.b #60,($FFFFC901).w ; set timer move.w (sp)+,d0

@cont3: movea.l (Go_SoundIndex).l,a0 sub.b #$A1,d7 bra SoundEffects_Common</asm>

After this, go to Sound_A0toCF and after

<asm> tst.b $24(a6) bne.w loc_722C6</asm>

add

<asm> clr.b ($FFFFC900).w</asm>

Then go to loc_7226E and replace

<asm> movea.l dword_722EC(pc,d3.w),a5</asm>

with

<asm> lea dword_722EC(pc),a5 movea.l (a5,d3.w),a5</asm>

Finally, go to loc_72276 and change

<asm> move.w (a1)+,8(a5) move.b #1,$E(a5)</asm>

to

<asm> move.w (a1)+,8(a5) tst.b ($FFFFC900).w ; is the Spin Dash sound playing? beq.s @cont ; if not, branch move.w d0,-(sp) move.b ($FFFFC902).w,d0 add.b d0,8(a5) move.w (sp)+,d0

@cont: move.b #1,$E(a5)</asm>

and now the Spin Dash sound revs.

Horizontal scroll delay

Sonic 2's Spin Dash implements a horizontal scroll delay, while the ported one doesn't (yet). The basic idea is to check a certain flag, and if it's non-zero, base scrolling on Sonic's X position a certain number of frames ago rather than his current X position. (Note that this feature can cause some problems with object interaction). So go to loc2_1ACD0 and change

<asm> move.w d0,($FFFFEED0).w ; move to $EED0</asm>

to

<asm> move.w d0,($FFFFC904).w ; move to $C904</asm>

And then go to ScrollHoriz2 and change

<asm>ScrollHoriz2: move.w ($FFFFD008).w,d0 sub.w ($FFFFF700).w,d0</asm>

to

<asm>ScrollHoriz2: ; XREF: ScrollHoriz move.w ($FFFFC904).w,d1 beq.s @cont1 sub.w #$100,d1 move.w d1,($FFFFC904).w moveq #0,d1 move.b ($FFFFC904).w,d1 lsl.b #2,d1 addq.b #4,d1 move.w ($FFFFF7A8).w,d0 sub.b d1,d0 lea ($FFFFCB00).w,a1 move.w (a1,d0.w),d0 and.w #$3FFF,d0 bra.s @cont2

@cont1: move.w ($FFFFD008).w,d0

@cont2: sub.w ($FFFFF700).w,d0</asm>

And then, to fix a bug with backwards horizontal scrolling, go to loc_65F6 and change it from

<asm>loc_65F6: ; XREF: ScrollHoriz2 add.w ($FFFFF700).w,d0 cmp.w ($FFFFF728).w,d0 bgt.s loc_65E4 move.w ($FFFFF728).w,d0 bra.s loc_65E4</asm>

to

<asm>loc_65F6: ; XREF: ScrollHoriz2 cmpi.w #-$10,d0 bgt.s @cont move.w #-$10,d0

@cont: add.w ($FFFFF700).w,d0 cmp.w ($FFFFF728).w,d0 bgt.s loc_65E4 move.w ($FFFFF728).w,d0 bra.s loc_65E4</asm>

to limit the maximum number of pixels the camera can scroll back by in a single frame.

Vertical scroll delay

In stock Sonic 1, the camera scrolls vertically as soon as Sonic looks up or ducks. This can be a bit annoying for the Spin Dash, however, so let's implement the delay present in Sonic 2 by using $FFFFC903 as our delay counter. Firstly, to fix a bit of incorrect code, go to loc2_1AD78 and change

<asm>loc2_1AD78: addq.l #4,sp ; increase stack ptr cmpi.w #$60,($FFFFEED8).w ; $EED8 only ever seems beq.s loc2_1AD8C ; to be used in Spin Dash bcc.s loc2_1AD88 addq.w #4,($FFFFEED8).w

loc2_1AD88: subq.w #2,($FFFFEED8).w

loc2_1AD8C: bsr.w Sonic_LevelBound bsr.w Sonic_AnglePos move.w #$60,($FFFFF73E).w ; reset looking up/down rts</asm>

to

<asm>loc2_1AD78: addq.l #4,sp ; increase stack ptr cmpi.w #$60,($FFFFF73E).w beq.s loc2_1AD8C bcc.s loc2_1AD88 addq.w #4,($FFFFF73E).w

loc2_1AD88: subq.w #2,($FFFFF73E).w

loc2_1AD8C: bsr.w Sonic_LevelBound bsr.w Sonic_AnglePos ;move.w #$60,($FFFFF73E).w ; reset looking up/down rts</asm>

Then go to Sonic_LookUp and change

<asm>Sonic_LookUp: btst #0,($FFFFF602).w ; is up being pressed? beq.s Sonic_Duck ; if not, branch move.b #7,$1C(a0) ; use "looking up" animation cmpi.w #$C8,($FFFFF73E).w beq.s loc_12FC2 addq.w #2,($FFFFF73E).w bra.s loc_12FC2

===========================================================================

Sonic_Duck: btst #1,($FFFFF602).w ; is down being pressed? beq.s Obj01_ResetScr ; if not, branch move.b #8,$1C(a0) ; use "ducking" animation cmpi.w #8,($FFFFF73E).w beq.s loc_12FC2 subq.w #2,($FFFFF73E).w bra.s loc_12FC2

===========================================================================

Obj01_ResetScr: cmpi.w #$60,($FFFFF73E).w ; is screen in its default position? beq.s loc_12FC2 ; if yes, branch bcc.s loc_12FBE addq.w #4,($FFFFF73E).w ; move screen back to default

loc_12FBE: subq.w #2,($FFFFF73E).w ; move screen back to default</asm>

to

<asm>Sonic_LookUp: btst #0,($FFFFF602).w ; is up being pressed? beq.s Sonic_Duck ; if not, branch move.b #7,$1C(a0) ; use "looking up" animation addq.b #1,($FFFFC903).w cmp.b #$78,($FFFFC903).w bcs.s Obj01_ResetScr_Part2 move.b #$78,($FFFFC903).w cmpi.w #$C8,($FFFFF73E).w beq.s loc_12FC2 addq.w #2,($FFFFF73E).w bra.s loc_12FC2

===========================================================================

Sonic_Duck: btst #1,($FFFFF602).w ; is down being pressed? beq.s Obj01_ResetScr ; if not, branch move.b #8,$1C(a0) ; use "ducking" animation addq.b #1,($FFFFC903).w cmpi.b #$78,($FFFFC903).w bcs.s Obj01_ResetScr_Part2 move.b #$78,($FFFFC903).w cmpi.w #8,($FFFFF73E).w beq.s loc_12FC2 subq.w #2,($FFFFF73E).w bra.s loc_12FC2

===========================================================================

Obj01_ResetScr: move.b #0,($FFFFC903).w

Obj01_ResetScr_Part2: cmpi.w #$60,($FFFFF73E).w ; is screen in its default position? beq.s loc_12FC2 ; if yes, branch bcc.s loc_12FBE addq.w #4,($FFFFF73E).w ; move screen back to default

loc_12FBE: subq.w #2,($FFFFF73E).w ; move screen back to default</asm>

Finally, to make the screen bias gradually reset during rolling, go to loc_131CC and change

<asm>loc_131CC: move.b $26(a0),d0 jsr (CalcSine).l</asm>

to

<asm>loc_131CC: cmp.w #$60,($FFFFF73E).w beq.s @cont2 bcc.s @cont1 addq.w #4,($FFFFF73E).w

@cont1: subq.w #2,($FFFFF73E).w

@cont2: move.b $26(a0),d0 jsr (CalcSine).l</asm>

And that's it! Let me know if I made any mistakes, or if there's anything still not covered. Here's a ROM after all these steps have been done, and here's the source code (with Puto's SEGA sound fix implemented instead of Esrael's for ASM68k compatibility).

Final code

Here is the final Spin Dash code for references: <asm>Sonic_SpinDash: tst.b $39(a0) ; already Spin Dashing? bne.s loc2_1AC8E ; if set, branch cmpi.b #8,$1C(a0) ; is anim duck bne.s locret2_1AC8C ; if not, return move.b ($FFFFF603).w,d0 ; read controller andi.b #$70,d0 ; pressing A/B/C ? beq.w locret2_1AC8C ; if not, return move.b #$1F,$1C(a0) ; set Spin Dash anim (9 in s2) move.w #$D1,d0 ; spin sound ($E0 in s2) jsr (PlaySound_Special).l ; play spin sound addq.l #4,sp ; increment stack ptr move.b #1,$39(a0) ; set Spin Dash flag move.w #0,$3A(a0) ; set charge count to 0 cmpi.b #$C,$28(a0) ; ??? oxygen remaining? move.b #2,($FFFFD1DC).w ; Set the Spin Dash dust animation to $2

loc2_1AC84: jsr Sonic_LevelBound jsr Sonic_AnglePos

locret2_1AC8C: rts

---------------------------------------------------------------------------

loc2_1AC8E: move.b #$1F,$1C(a0) move.b ($FFFFF602).w,d0 ; read controller btst #1,d0 ; check down button bne.w loc2_1AD30 ; if set, branch move.b #$E,$16(a0) ; $16(a0) is height/2 move.b #7,$17(a0) ; $17(a0) is width/2 move.b #2,$1C(a0) ; set animation to roll addq.w #5,$C(a0) ; $C(a0) is Y coordinate move.b #0,$39(a0) ; clear Spin Dash flag moveq #0,d0 move.b $3A(a0),d0 ; copy charge count add.w d0,d0 ; double it move.w spdsh_norm(pc,d0.w),$14(a0) ; get normal speed tst.b ($FFFFFE19).w ; is sonic super? beq.s loc2_1ACD0 ; if no, branch move.w spdsh_super(pc,d0.w),$14(a0) ; get super speed

loc2_1ACD0: ; TODO: figure this out move.w $14(a0),d0 ; get inertia subi.w #$800,d0 ; subtract $800 add.w d0,d0 ; double it andi.w #$1F00,d0 ; mask it against $1F00 neg.w d0 ; negate it addi.w #$2000,d0 ; add $2000 move.w d0,($FFFFC904).w ; move to $EED0 btst #0,$22(a0) ; is sonic facing right? beq.s loc2_1ACF4 ; if not, branch neg.w $14(a0) ; negate inertia

loc2_1ACF4: bset #2,$22(a0) ; set unused (in s1) flag move.b #0,($FFFFD1DC).w ; clear Spin Dash dust animation move.w #$BC,d0 ; spin release sound jsr (PlaySound_Special).l ; play it! move.b #8,($FFFFFF5B).w ; set afterimage counter to 8 bra.s loc2_1AD78

ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ

spdsh_norm: dc.w $800 ; 0 dc.w $880 ; 1 dc.w $900 ; 2 dc.w $980 ; 3 dc.w $A00 ; 4 dc.w $A80 ; 5 dc.w $B00 ; 6 dc.w $B80 ; 7 dc.w $C00 ; 8

spdsh_super: dc.w $B00 ; 0 dc.w $B80 ; 1 dc.w $C00 ; 2 dc.w $C80 ; 3 dc.w $D00 ; 4 dc.w $D80 ; 5 dc.w $E00 ; 6 dc.w $E80 ; 7 dc.w $F00 ; 8

ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ

loc2_1AD30: ; If still charging the dash... tst.w $3A(a0) ; check charge count beq.s loc2_1AD48 ; if zero, branch move.w $3A(a0),d0 ; otherwise put it in d0 lsr.w #5,d0 ; shift right 5 (divide it by 32) sub.w d0,$3A(a0) ; subtract from charge count bcc.s loc2_1AD48 ; ??? branch if carry clear move.w #0,$3A(a0) ; set charge count to 0

loc2_1AD48: move.b ($FFFFF603).w,d0 ; read controller andi.b #$70,d0 ; pressing A/B/C? beq.w loc2_1AD78 ; if not, branch move.w #$1F00,$1C(a0) ; reset spdsh animation move.w #$D1,d0 ; was $E0 in sonic 2 move.b #2,$FFFFD1DC.w ; Set the Spin Dash dust animation to $2. jsr (PlaySound_Special).l ; play charge sound addi.w #$200,$3A(a0) ; increase charge count cmpi.w #$800,$3A(a0) ; check if it's maxed bcs.s loc2_1AD78 ; if not, then branch move.w #$800,$3A(a0) ; reset it to max

loc2_1AD78: addq.l #4,sp ; increase stack ptr cmpi.w #$60,($FFFFF73E).w beq.s loc2_1AD8C bcc.s loc2_1AD88 addq.w #4,($FFFFF73E).w

loc2_1AD88: subq.w #2,($FFFFF73E).w

loc2_1AD8C: jsr Sonic_LevelBound jsr Sonic_AnglePos ;move.w #$60,($FFFFF73E).w ; reset looking up/down rts

End of function Sonic_SpinDash

</asm>

SCHG How-To Guide: Sonic the Hedgehog (16-bit)
Fixing Bugs
Fix Demo Playback | Fix a Race Condition with Pattern Load Cues | Fix the SEGA Sound | Display the Press Start Button Text | Fix the Level Select Menu | Fix the Hidden Points Bug | Fix Accidental Deletion of Scattered Rings | Fix Ring Timers | Fix the Walk-Jump Bug | Correct Drowning Bugs | Fix the Death Boundary Bug | Fix the Camera Follow Bug | Fix Song Restoration Bugs | Fix the HUD Blinking | Fix the Level Select Graphics Bug | Fix a remember sprite related bug
Changing Design Choices
Change Spike Behavior | Collide with Water After Being Hurt | Fix Special Stage Jumping Physics | Improve the Fade In\Fade Out Progression Routines | Fix Scattered Rings' Underwater Physics | Remove the Speed Cap | Port the REV01 Background Effects | Port Sonic 2's Level Art Loader | Retain Rings Between Acts | Add Sonic 2 (Simon Wai Prototype) Level Select | Improve ObjectMove Subroutines | Port Sonic 2 Level Select
Adding Features
Add Spin Dash ( Part 1 / Part 2 / Part 3 / Part 4 ) | Add Eggman Monitor | Add Super Sonic | Add the Air Roll
Sound Features
Expand the Sound Index | Play Different Songs Per Act | Port Sonic 2 Final Sound Driver | Port Sonic 3's Sound Driver | Port Flamewing's Sonic 3 & Knuckles Sound Driver | Change The SEGA Sound
Extending the Game
Load Chunks From ROM | Add Extra Characters | Make an Alternative Title Screen | Use Dynamic Tilesets | Make GHZ Load Alternate Art | Make Ending Load Alternate Art | Add a New Zone | Set Up the Goggle Monitor | Add New Moves | Add a Dynamic Collision System | Dynamic Special Stage Walls System | Extend Sprite Mappings and Art Limit | Enigma Credits | Use Dynamic Palettes
Miscellaneous
Convert the Hivebrain 2005 Disassembly to ASM68K
Split Disassembly Guides
Set Up a Split Disassembly | Basic Level Editing | Basic Art Editing | Basic ASM Editing (Spin Dash)