I hope this is the right place to ask about this, it's a little hard to nail down where it belongs. Please feel free to move to a better place if needed.
I extracted the NES Online Switch app and the latest update for it. I found that the majority of the games inbuilt are standard NES roms that load in Mesen without issue.
What interests me though is that there are a couple of games that appear to be Famicom Disk System disk images, and none of them run on Mesen. The NES Online app does include a FDS BIOS, and its hash matches what you would find for it in the No-intro set. It also has a "no_wait" bios that I'm guessing is meant to speed up loading the game.
What puzzles me is why the FDS games don't load in Mesen, they just hang on the loading game screen on in the FDS BIOS. Looking at SMB2, the main game I'm interested in, and comparing it to the No-intro headerless counterpart image in a hex editor, they look very similar. The only thing I found odd is that when I turn on Mesen's debugger and use the trace logger, it looks like it's repeatedly trying to do "JMP $E7A4", so it seems like maybe the code isn't valid there for some reason?
I figured I'd check and see if anyone has investigated this. I've googled this some and haven't found much information to speak of.
I extracted the NES Online Switch app and the latest update for it. I found that the majority of the games inbuilt are standard NES roms that load in Mesen without issue.
What interests me though is that there are a couple of games that appear to be Famicom Disk System disk images, and none of them run on Mesen. The NES Online app does include a FDS BIOS, and its hash matches what you would find for it in the No-intro set. It also has a "no_wait" bios that I'm guessing is meant to speed up loading the game.
What puzzles me is why the FDS games don't load in Mesen, they just hang on the loading game screen on in the FDS BIOS. Looking at SMB2, the main game I'm interested in, and comparing it to the No-intro headerless counterpart image in a hex editor, they look very similar. The only thing I found odd is that when I turn on Mesen's debugger and use the trace logger, it looks like it's repeatedly trying to do "JMP $E7A4", so it seems like maybe the code isn't valid there for some reason?
I figured I'd check and see if anyone has investigated this. I've googled this some and haven't found much information to speak of.
