I'm working on JJXB's Double Dragon II 3DN and I now see what he meant by "garbage at the bottom of the screen buffer". See photo below for explanation:

I checked this out on a regular emulator, and sure enough it shows up there too, so this is a problem with the original game.

Would it be possible to mask this in your emulator without removing the sprites when they are supposed to be used?

I figure it's probably not possible, but thought I should ask.

UPDATE:

As you can see from the picture below, this can be hugely distracting from the information at the bottom of the screen when it gets out of hand. I never really paid it much notice on the original game when the sprites aren't being expanded, but now that they're 3D you can't read anything when this happens.

UPDATE 2:

Wow! Look how the numbers from the bottom of the screen show up at the top while going up the ladder!

I wasn't able to verify this happens without the emulator, but there definitely is a constant mess of garbage without the emulator on the top and sides as you're moving around. We'll probably just have to live with it, but it's a shame that these minor annoyances are so prominent once you 3D the game.

Glitches at border is the trademark issue of Nes. It just becomes serious in 3D context. I will have to think about a solution anyway.

That's what I figured geod. Don't beat yourself up too much about it though. DD2 is the only game I've worked on so far that is this insane about it. Even DD1 isn't really that bad although both games really need to be gone through "frame by frame" a few times to fix other weird issues.

Maybe one day you can fix it? Maybe not.

Tons of other stuff that needs doing now that's a lot easier to do though, right? :)