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Sonic 1: Sonic 1 Beta Remake v1.03B
Research / Megadrive Programming

Please note: this guide has been written in 2003-2004, when I was learning the intricacies of Megadrive programming. As a result, there are some errors in some pages and in some sample source code. I advise caution when using this guide. Also, my English language... prowess wasn't that great back then so forgive the bad grammar.

Somewhere on my to-do list is a complete rewrite of this section and a much better MD reference, but until then, I'm keeping this online. And for nostalgia, of course. (Note added in 2009)

Welcome to my 68k programming guide. You will learn about the basics (adding, substracting etc.) as well as more exciting things, like editing objects in Sonic engine or even programming your own ones =P

REMEMBER: If you don't understand something, you are lost, you have comments or you've seen some errors (hmmm =P), post it on the forums. I'll not only help you, but I'll improve and make my guides better (I know they aren't great XD). And one note: Don't worry if you don't understand something, it's not the end of the world. This is assembly, it's not easy...

Have fun =)

ASM Guide:
1. Basics
2. Let's start
3. Compares, branches...
4. Logical operations
5. Editing the game code
6. Loops & arrays

Genesis informations:
1. 68000 memory map
2. ROM header
3. Genesis security
4. I/O ports
5. VDP
6. DMA
7. VDP programming calculator

Useful subroutines:
1. Reading the joypads
2. PSG subroutines

Commented code:
1. Code template
2. PSG test using all 3 channels
3. SRAM test
4. Wav Player v1.0
5. FM Song Player

1. 32x SDK - official 32x dev kit for 32x developers - sample sources, debuggers etc.
2. Sega2f - Sega's official docs about Sega Mega Drive, fixed by Nemesis

More to come...

Everyting is © me, so please just tell me if you want to copy/steal/whatever anything from here. Thanks in advance.

Thanks to:
- Charles MacDonald (great docs),
- Bart Trzynadlowski (great 68k disassembler),
- Jimmy Mardell (an old 68k guide),
- St?phane Dallongeville (great smd emu)

© 2004-2006 drx, All content on the website is licensed with the MIT license,
unless otherwise noted, meaning you can pretty much do anything you want with it.