Sonic 1 SMS Disassembly

Discussion in 'Engineering & Reverse Engineering' started by Ravenfreak, Jan 24, 2011.

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  1. Ravenfreak

    Ravenfreak

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    So I came to the conclusion that I will release my disassembly to the public today, since I'll need more people to identify stuff. It's in text format for now, but it does fully build a modified ROM. Do read the ReadMe.txt file to see what I've already found and such. It's far from being SVN worthy today, but I'd like to change that in the future. Edit: New download link, and changes from the previous one. Copy/Paste from the ReadMe file:

    Alright, this is the second release nothing too big. Now it builds a ROM that's byte by byte similar to the original game, a few comments have been edited, and hex edit is gone. (Though I primarly blame my girlfriend, oathsan on SR for moving the program into the folder. Yeah I have to use her computer. :V)

    <a href="http://www.mediafire.com/?em6e2am5xsmqepzl" target="_blank">http://www.mediafire.com/?em6e2am5xsmqepzl</a>
     
  2. nineko

    nineko

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    Great. Make sure to crosspost this on <a href="http://www.smspower.org/forums/viewforum.php?f=3" target="_blank">smspower</a> :)
     
  3. SegaLoco

    SegaLoco

    W)(at did you say? Misfit
    Woo, hopefully this is the year of the disassembly! There are a load of games that need disassemblies :P (In fact, after I'm considerably far along in Sonic CD, I'm considering starting on the Sonic Xtreme 718 build)
     
  4. Ravenfreak

    Ravenfreak

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    A disassembly of Sonic Xtreme eh? Sounds awesome good luck with it. ^_^ Okay brief update, I've identified the water height address, as well as the addresses for X an Y camera scroll. Water height: $D248, X:$D251, Y:$D252. Edit: there's a new release check out the first post. :v:
     
  5. Ravenfreak

    Ravenfreak

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    Soo I found out where the game stores the sound effects and music data. Taken from the new Readme file:

    <!--quoteo--><div class='quotetop'>QUOTE </div><div class='quotemain'><!--quotec-->$C5AE music data, such as notes, coordination flags, ect. starts here. Each PSG channel has 8 bytes of data.
    $C5E7- volume control, specifically makes the Noise Channel and CH 3 louder and lowers the volume
    of other channels.

    $C171 contains sound effect data. Every sfx in the game gets loaded into memory here. I have yet to figure out what each byte does.<!--QuoteEnd--></div><!--QuoteEEnd-->
    In the source code, the sfx data starts at line 2407 and the music data starts at line 2841. Also in the Readme file, there is a PAR code I've made myself that gives you a huge Time Bonus. :v: Here's a new link:
    <a href="http://www.mediafire.com/?plk2zfwstf0ksq1" target="_blank">http://www.mediafire.com/?plk2zfwstf0ksq1</a>
    Edit: Just out of curiosity, is this wiki worthy? ^^'
     
  6. kram1024

    kram1024

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    Part of the new Team Revamped; Kraminator Special Series disassemblies; Sonic 3 Sound Driver porting guides; KENS 1.5; smps studio; various non-sonic related things
    I wonder if there is a way to get the game to use only 1 KB of system ram so that a colecovision port can be made with this, or possibly unused video ram that can help with the port. the coleocovision has a compatible video chipset and the exact same psg chipset as a sms, just only 1 KB of ram instead of the 8 KB that a sms has, or would simply replacing bios calls with sonic1 code do the trick?
     
  7. Dr. Kylstein

    Dr. Kylstein

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    The ColecoVision doesn't support the video mode that Sonic 1 (and most SMS games) uses. Also, 7KiB can make a lot more difference than you might think.
     
  8. Billy

    Billy

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    If Sonic 1 SMS was to be ported to anything, it would have to be NES, for the lols.

    The future of rom hacks looks bright, what with all these disassemblies coming out.
     
  9. Chilly Willy

    Chilly Willy

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    I know there have been a few attempts at porting this to the PC-Engine/TG-16. It should be pretty straightforward. The main issue is converting the Z80 code to 6502.
     
  10. Ravenfreak

    Ravenfreak

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    Also, the colecovision is more similar to the SG-1000 and SC-3000 than the SMS, since both have support for 16 colors only, as well the SMS uses Mode 4 of the VDP chip, whereas the Colecovision only uses mode 1 and 2. But of course the SG-1000 still uses 8kb of RAM. If you were to port this, you might want to attempt to port it to one of those consoles first, which would make it much easier to port it to the colecovision. But you'd have to make the ROM smaller, since Colecovision cart sizes are only 8/16/24/32 KB, and Sonic 1 is 256 KB in size. So yes, it's plausible but would take a while to achieve, given if you know what you're doing.
     
  11. kram1024

    kram1024

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    actually raven freak, there are a few (rare) mode 3 colecovision games and the documentation tells you how to use it, but due to how choppy it looks, very few games use it.
     
  12. Ravenfreak

    Ravenfreak

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    Oh really? I didn't know that. ^^" Though I'm not really familiar with the colecovision. :v: But it would be awesome to see a port of this. Do you plan on working on one? :)
     
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