could you take a look at snes_update_objects_rto? I cannot see exactly your idea would fit the SNES behavior (which is not something I made up, it's the way byuu describes and implement it, and he ran *a lot* of test on the hw about this flag): the flag can be updated at each scanline, not only when the register is accessed by the snes_io handler. also, notice that snes_oam is going to be a PPU thing only.
maybe we could add an handler which writes back to the register from the PPU, but would the handler be called at the right moment by the video_update?

Last edited by etabeta78; 04/01/10 02:35 PM. Reason: better snes behavior description