This all started out simply as a curiosity project of mine. Since the dumped street fighter 2 arcade hacks played just like the real thing and used data from the regular champion edition dump I was curious what exaclty makes these bootleg hacks "tick". The bootleg hack dumps only contain two files which are roms that contain the game programming, the rest of the files it uses are from champion edition. Here's a look at the m5 roms in a hex editor compared to the normal champion edition rom. The champion edition rom is the code at the top:
You can see that the M5 hack roms have the data split in an interleaved pattern. I found a dos based tool on the internet that interleaved the two files back together and this's what it turned into:
The code looks pretty much the same as champion edition so obviously this game is just a severely hacked up champion edition rom. I tried burning these roms and running them on my cps1 but sprites weren't drawing properly and it wasn't reading controller inputs. I took a look inside the cps1.c file that emulators use and certainly enough the m5 bootleg and other bootlegs were only released on custom bootleg pcbs that draw sprites in the opposite direction and have different controller inputs. Luckily the m5 hack says "920313" on it so I took the 920313 champion edition roms and copied parts of hex from the champion edition dumps into my cleaned up m5 dumps until I got the game running as a normal cps1 game in an emulator. Then I burned the game to eproms and it ran fine on my cps1 arcade board. I found some programming I forgot to copy that was causing the game to crash and fixed it.
The next step was to improve this hack. Since I got the hack roms compatible with champion edition I was able to "reverse engineer" the code by copying hex from the champion edition roms until it effected the programming I was looking to change. Basically anything that they bothered changing between champion edition and the m5 hack I was able to hunt down and change myself. I did the following...
I removed the computer opponents ability to teleport into my face whenever it felt like it as this was more annoying than anything. I made ryu and kens uppercuts launch you across the screen. I made guiles bicycle kick launch you across the screen thanks to some code I found in the m6 dump. I made sagats uppercut launch you across the screen again thanks to code from m6. I changed the bootup screen from saying "920313" to saying "SHENG LONG" just so people would know the name of my custom hack.
I also had to use the 21 rom from redwave because whoever dumped the m5 bootleg forgot to dump the 21 rom which contained some of the hacked programming. In fact running M5 on an emulator it's missing that undumped programming. I found a guy who actually own a M5 bootleg pcb and he confirmed that my m5 version with the redwave 21 rom runs just like the pcb. Before I used the red wave 21 rom the fireballs moved at normal speed but on the m5 pcb they're severely slowed down so you can flood the screen with them. Luckily all of these hacks were made by the same company so a lot of them share the same hacked code.
I tried using the mame debug mode to help me find more hex values to change but mame debug is complicated and not user friendly at all so I gave up on using that. If there's anyone who's good with using mame debug mode to help me find other areas of the code to edit that would be much appreciated. Physics in the game such at super move horizontal and vertical speed are adjustable simply by changing 1 hex value for each. Once I find the hex value it's just a matter of tweaking it so it looks great and so the character doesn't glitch out of the software and endlessly fall through the floor.
I'm happy to announce that I'm capable of converting cps1 street fighter 2 champion edition, turbo, and even rainbow into the m5 hack. I can also convert a board to rainbow set 3, or my custom hack. These unofficial champion edition hacks contain a lot of stuff that was later used in official capcom games and they're very well made. Some of these hacks even tried to balance the game out by making previously weak characters more powerful to even the playing field. Not all of the things they changed were great ideas but there certainly is a lot of great things that were added to the game through these various hacks.
Here's the demo video showing off the hack running on a regular cps1.
*edit*
If anyone is interested in playing my hacked roms just let me know. I don't know if this forum has a "no rom posting" rule like most forums. I can post a version that's fully playable in common emulators like winkawaks or even mame. But it's quicker getting it going in winkawaks.
