(Original guide by Qjimbo)
You might not think the words "basic" and "assembly" could belong in the same sentence, however what we plan to do in this tutorial takes a more modular approach to our disassembly than you might have thought was possible.
And that is today's project! We are going to use the Early Prototype disassembly that drx made, reason being that he took care over to ensure it used all the same label names as Hivebrain's Sonic 1 disassembly. This means porting data from it is a lot more straightforward than from the existing Sonic 2 disassembly.
You can use any text editor to edit the disassembly, however I recommend using ConTEXT and Ambil's M68K Highlighter.
Text editor for editing the disassembly.
Highlighter that allows clearer code editing. After installing ConTEXT, place this in your C:\Program Files\ConTEXT\Highlighters folder.
The disassembly of the Sonic 2 Nick Arcade Beta
Useful resource for understanding 68k assembly instructions.
The set of data we reach is this:
Obj01_MdNormal: ; DATA XREF: ROM:Obj01_Modes?o bsr.w Sonic_Spindash bsr.w Sonic_Jump bsr.w Sonic_SlopeResist bsr.w Sonic_Move bsr.w Sonic_Roll bsr.w Sonic_LevelBoundaries jsr SpeedToPos bsr.w Sonic_AnglePos bsr.w Sonic_SlopeRepel rts
This is the table of Sonic's moves. You can see the Spindash is in there, so we will put it into Sonic 1.
The next step is to select from Sonic_Spindash: all the way down to ; End of function Sonic_Spindash. Copy this into the clipboard.
; End of function Sonic_JumpHeight [CODE] ; --------------------------------------------------------------------------- ; Subroutine to slow Sonic walking up a slope
.....Oh dear. This doesn't look right. But the Spindash is there, at least! We need to change the animation, go to
We have now put a Spindash in Sonic 1! In part 2, we will show you how to reset the camera when dashing, as well as share some more ASM goodies! Bye for now!
|SCHG How-To Guide: Sonic the Hedgehog (16-bit)|
|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 | 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|
|Add Spin Dash ( Part 1 / Part 2 / Part 3 / Part 4 ) | Add Eggman Monitor|
|Expand Music Index From $94 to $9F | Extend Music Slots | Play Different Songs Per Act | Expand Music Index to Start at $00 | Port Sonic 2 Final Sound Driver | Port Sonic 3's Sound Driver|
|Extending the Game|
|Load Chunks From ROM | Add Extra Characters | Make an Alternative Title Screen | Use Dynamic Tilesets | Make GHZ 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|
|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)|