Sonic CD 510 Disassembly

Anyone here really good with Sega CD. And I mean REALLY good? Well, would you like to commit to a community disassembly of Sonic CD 510? I'm already well into the boot sector or whatever (the data before the binary file data starts) and I'm having a bit of trouble figuring it out, but if anyone wants to grab just one file from the ISO and disassemble it, we can work this out in no time. I'll also upload what I have disassembled of the entirety of the ISO for anyone to work on as they see fit. Once we get this thing considerably disassembled, perhaps a new svn entry could be setup for this disassembly to offer a bit of control to who is contributing what, and to keep tabs on what needs to be done and what is already done. One thing you'll need if you aren't a SegaCD guru is the set of Rex Sabio SegaCD manuals. I won't tell you how to find these<a href="http://megadrive.org/~elbarto/md/Docs/Official%20Sega%20CD%20Manual/" target="_blank">,</a> but I bet you could. Anyway, without further rambling, here is the IDA database (It's IDA 4.3, not sure if it's compatible with newer versions, if not, Data Rescue is retarded and I'll see what I can do)

IDA Database: http://www.mediafire.com/?9f9gm5qdr7s5bb5

Thanks and good luck

Edit: Also, if you choose a file, post that you'll do it, we don't need 50 people doing ATTACK.BIN :P

 

Thank you so much. Now riddle me this, is this Sonic CD final or the 510 like I'm doing. (It can still help if it's final, but I'm just curious)

 

Here's the Initial Program code completely disassembled and ready for reassembly. It assembles 1:1 with the original, I checked

http://www.mediafire.com/?mdy3xbi10oo4ecb

It seems to setup some system-wide exception defaults and setup the MMD loader code.

Edit: Also, to anyone not so Mega CD savvy, this portion of code runs on the MainCPU map. The SP, which I hope to upload by the end of today, runs on the SubCPU.

 

I'm disassembling the 510 version because, as a prototype, it may have interesting stuff hiding in it. As for the incbining, I'm going to do that until I can figure out how to get all the org and rorg tags to play nice with each other.

Edit: Now featuring SP code :D (Not fully commented, but I'm still working on that, also, doesn't build 1:1 due to the whole 0(ax) to (ax) thing, but it's a start)

http://www.mediafire.com/?8f79h7bo072ikgs

 

Well, to report a find I didn't mention I guess, the SP code mentions two files DISP0_.MMD and DISP1_.MMD which I can't find anywhere in the ISO. They're intermingled into the level loader table after a long set of references to R11A__.MMD and right before R31A__.MMD (R2..probably not :P) but interesting nonetheless. I'm afraid that is all I can find related to that though..unless the data is present in the ISO and just not in the ISO header (I.e. unlisted like the IP and SP) If that is the case, then... I dunno... :p

 

Yup, just tested changing that pointer to either DISP reference, just crashes both CPUs. Whatever these files were, they were present in the internal code, but I guess left out of this build (as it was for magazines and such). Whatever they were, Sega left the text alone for whatever, reason, probably because they had no reason to remove it if it would never be reached. My guess is that they were test screens for good and bad ending, like, say you got good ending, then DISP0_.MMD would just flash up a screen saying "You got the Good Ending" and likewise with the bad ending, hence why they aren't present in a proto like 712 in which the final videos are implemented. Who knows though, we won't until another proto surfaces...hopefully...

 

As far as I know that is remaining a secret for now...

 

Update :D

So I decided to poke around in IPX___.MMD and wow, it has all the level loading code and I could essentially revert Sonic CD 510 to its internal state (all levels loading sequentially, no Comin' Soon after TTZ) except there are level load hooks for DISP0_.MMD and DISP1_.MMD (obviously they must've been level-like data as they are thrown in with level loading in every instance that I see them). As for R2, chances are looking slimmer and slimmer, all the level load tables and whatnot don't even have space for a probable R2, only space for those DISP files. Once I am done disassembling IPX I will upload that along with an ISO with full gameplay enabled (except special stages from the big ring, I'm still figuring out exactly what needs to be done to get that working). Stay tuned!

 

Nothing yet, I'm not picking apart levels atm, but system code. IPX basically gets loaded on top of the IP. The IP only serves to tell the SP to load the IPX...kinda redundant right xD

Edit: Update, here is the build package with IPX and mmdmerge included :D <a href="http://segaloco.com/!crap/retro/CD510.zip" target="_blank">http://segaloco.com/!crap/retro/CD510.zip</a>

 

Bumping with good reason: <a href="http://www.segaloco.com/!crap/retro/soncd.7z" target="_blank">http://www.segaloco.com/!crap/retro/soncd.7z</a>

This is an iso using a modified IPX___.MMD which allows all levels to be loaded (just like a regular game). I'd say you can play all the way through... but, it's hard without debug mode :P Stay tuned for more, along with a version of mmdmerge that ACTUALLY WORKS