With tip-off from Jorge, and some help researching, we found a very interesting piece of code inside Sonic 3, and further found there is a lot more to this code than meets the eye in the S3C and S&K protos. This piece of code would activate as the user trap $F, and it would call all kinds of weird routines and codes. We were excited as we thought this may have been used as a debugger and would give some great insight into things, but it turns out a lot of the code is not useful in any way. However, given the nature of it, it is still rather interesting to speculate and see what it could have been used for. As it stands, we really do not know. We have some idea of what code is called and what it does (except some that just leave whatever at dregs or point to data). However, the puzzle pieces really do not fit well. Some codes can be used for obtaining rings, score, changing level or playing music, but the other do some of the most mundane things. I have compiled a list of routines known so far in Sonic 3C 418 beta. Jorge also kindly made a ROM that allows you to call these routines by pressing A while debug mode is active. It will take ring count as the routine number (will multiply by 4), and starting from $FF0000, longword moves data to d0-d5/a0-a5, allowing you to modify the register values for testing. I was able to successfully go to ICZ1 by using this ROM. So far, this is all we know or understand about this. It seems plausible this is used for debugging purpose, but how, why, or when is still unknown to us. Any input, speculation and research would be appreciated.