I've finally released the June 2005 version of my Sonic 1 disassembly.

New stuff:
- Most of the subroutines are labelled
- Many things have been commented
- This version compiles a lot faster
- Compressed data is automatically decompressed (recompression is not automatic by default because it's very slow)
- Some parts of the ASM are separated into _ANIM, _INC and _MAPS folders
- The compiled ROM is automatically padded to be a "power of 2" in length (i.e. $80000, $100000, $200000)

IDB, for use with IDA Pro:

http://sonicology.hacking-cult.org/S1idb_June05.rar

Split ASM:

http://sonicology.hacking-cult.org/S1asm_June05.rar

Yes, there are a few unused bits of code:

MoveDemo_Record - for recording demos.

Just after locret_132D2 - subroutine that squashes Sonic and stops him moving. This was possibly used when Sonic runs into a wall at speed, although there's no way of knowing for certain.

FloorLog_Unk - records something to do with collision. I don't know what.

Just after nullsub_2 - limits Sonic's speed in the special stage.