[Kroc]

Wow, what a response -- in just a few hours!

To answer some questions:

Quote

I wonder if there are any remnants of Spring Yard Zone or Star Light Zone as well?

There are a large number of unused objects in the game which have code, but probably missing graphics for them. (offsets: $9B75, $9BE8, $9C70, $96F8, $96A8, $8218, $83C1, $94A5, $AE35, $B0F4, $8ECA, $8F6C, $BCDF)
When I can reverse engineer how the objects work I might be able to work out what the AI these objects have and give them new graphics.

I'm in the middle of unpicking the music data, so I will post here if I find any more unused songs.

Quote

What's the offset in the original ROM where the song can be found?

There's a pointer table for the game music at $C716. Green Hill begins at $C7D0 and I discovered Marble Zone wedged inbetween it and the next song. You can find it at $CD0A.
I used the music notes on the SCHG to unpick the bytes, so credit for this discovery must go to ValleyBell.

I don't know how to do VGM stuff, but I hope this data helps the peeps who know.

Quote

judging by your past activity on the wiki page for it you've done some impressive work

I've rewritten most of that page already and plan to completely overhaul it. When I started there were a large number of unknown bytes in the level headers and I've now gotten that down to 1: Unknown Byte "9" is actually a bank number for loading the sprite data -- more proof the game used to be bigger -- but I haven't added that info to the wiki yet.

Since the response has been so nice, I'll share with you my current disassembly -- just be warned that this is only 5% done, but I've mostly got it formatted in ASM and have started commenting it.

Sonic 1 Master System Disassembly: (23-NOV-13) http://camendesign.co.uk/_stuff/S1.sms.asm

[McAleeCh]

Wow, this is incredible! Aside from the Basaran/Batbrain graphics found only in the Game Gear version of the game, I wasn't aware of any indication that Marble Zone might have been intended for the Master System version of the game at some point. Congratulations on the amazing find, Kroc! Sonic 1 on the Master System is a game that I've always had a soft-spot for, as my brother's Master System II with the built-in version of Sonic 1 was the first mainstream games console that we ever owned.

I wonder what other secrets this game holds...

That reminds me, does anyone know if the built-in version of Sonic 1 has ever been dumped? I can only think of one difference when compared to the emulated versions I've played since then - it didn't display the graphics of Sonic singing into the microphone that the cartridge version shows over the end credits, instead showing the overview of South Island that appears on the intermission screen between levels. That's stuck in my head very clearly - I remember my brother describing the "Singing Sonic" to me when we first completed the game, as he was surprised not to see it given that he'd previously seen it on his friend Rob's copy of the game, which was the cartridge version.

This post has been edited by McAleeCh: 23 November 2013 - 06:28 AM

[Techokami]

McAleeCh, on 23 November 2013 - 06:27 AM, said:

That reminds me, does anyone know if the built-in version of Sonic 1 has ever been dumped?

Yep, it's on SonAR as "European_SMS_BIOS_(Sonic_the_Hedgehog)_(E)_[!]"

[MathUser]

I added the info to the wiki: Game Secrets:Sonic the Hedgehog (8-bit). Feel free to add more info as you get it.

[ashthedragon]

Holy shit!!! This is the best discovery I've seen in a long while ( and we have not been short of amazing research results lately...). Sonic 1 and 2 for the Master System are my favourite Sonic Games, and finding something like this is...wow. Great job there!!!

[drx]

Nice find.

There's a Sonic 1 MS prototype that I've been after that is supposedly more like Sonic 1 for Megadrive, this would be in line with that.

[Kroc]

I would give one of my testicles to play a 512K version of Sonic 1 before they cut it down. I love the elegance and simplicity of the art (and backgrounds) that are able to communicate far more complexity than is really there -- I would love to have seen how they did Marble Zone (my favourite).

My goals with this project are:
1. Understand what every byte in the ROM does -- it's old enough that we should really understand this by now
2. Create visual and intuitive interfaces to edit every aspect of the game worth editing
3. Use the above two to create my own total conversion game "Kroc the Crocodile"

[Andrew75]

Seems we get finds in clusters here on Retro.. The Jetzones music thing, this and Metal Sonic boss stage from sonic x-treme.

This post has been edited by Andrew75: 23 November 2013 - 12:56 PM

[Kroc]

I've just finished examining the remaining music data and there are no other hidden tracks, except for what might be some overwritten music data from $FB27 to $FFB1.
The last track in the data block begins at $FA26, there follows four words which are offsets into the four sound channels. No.4 (+$00FB) begins at $FB21 and only runs for a few bytes as it is essentially an infinite loop of silence (no white noise).

Therefore all the sound data from $FB27 onwards is not, as far as I can tell, part of a known track. However, it is missing a song header, and looks like a partial channel 3 and complete channel 4 of an unknown song.
I may, of course, be entirely wrong.

Is there anybody who would know how to re-piece this together and get this to play?

I've updated my disassembly to include these findings, search for "_fb27".

This post has been edited by Kroc: 23 November 2013 - 01:58 PM

[Sodaholic]

This is amazing, the discoveries just never stop even after all these years!

I suspect the similar level art are remnants of attempts of making those actual levels.

[ArrYaReadyKids]

That's insane! It sounds like there's a load of other secrets in the game too. I'm keeping a close eye on this!

[Glitch]

Great find! It's good to see the 8bit Sonic getting some love again.

drx, on 23 November 2013 - 11:56 AM, said:

Nice find.

There's a Sonic 1 MS prototype that I've been after that is supposedly more like Sonic 1 for Megadrive, this would be in line with that.

If you ever need donations for that give me a shout!

[Sodaholic]

drx, on 23 November 2013 - 11:56 AM, said:

There's a Sonic 1 MS prototype that I've been after that is supposedly more like Sonic 1 for Megadrive, this would be in line with that.

Do you have any leads on who may have it? I don't want to know who, just if the trail's cold or not. How did you hear about it?

This post has been edited by Sodaholic: 23 November 2013 - 06:31 PM

[Shoemanbundy]

It's discoveries week here at Retro!

A drx comeback next would be nice, been a long dry spell.

[Master Emerald]

muteKi, on 23 November 2013 - 12:22 AM, said:

Is there a .sgc file for Sonic 1?

There is but just for Sonic 1 GG :/