In the NMI, the scrolling is set to Horizontal and Vertical values incerased every frame. In the reset, i have a loop that will handle Split-Screen Scrolling. It checks for sprite #0 found, on a sprite that's between the upper and the middle of the screen. From there, the scrolling is set to 0 to be kept silent, and it works. But then more far down i want the scrolling to be set to a Horizontal and Vertical value.
How do i make that work?
I tried many ways and i got the screen to glitch, or only scroll Horizontally.
Not bot Horizontal and Vertical.
Ive tried to reset $2006, then set the scroll, and other methods.
Anybody who knows what im doing wrong?

Split-screen vertical scrolling can be tough, I remember reading an interview with Andrew Davies where he talked about how he did it on the game Bigfoot.

AFAIK, you pretty much have to use $2006 because the PPU ignores vertical scroll writes outside of vblank (or something like that). That's probably why status bars and such are usually at the bottom of the screen on NES.

Check out my scrolling doc on the main page. At the end of the document, it discusses how to update the scroll registers to any value on the fly, by alternating writes between $2005 & $2006.

And BTW Memblers, the way that was done in Bigfoot, according to Andrew's post on the mailing list a couple of years ago, was that he basically waited for the appropriate scanline to make a dual write out to $2006. Since the write cause the fine- v scroll to be reset to 0, you can see why it effectively allowed smooth vertical split screen scrolling.

I made it work now, thanks to your document :D
thanks for the help.