>>720535939
>Because OAM is DRAM, which needs to be refreshed frequently, the contents of OAM begin to decay quickly when rendering is turned off via PPUMASK ($2001). During rendering, sprite evaluation will continually refresh the OAM data.
one issue is that if you disable rendering for any length of time, the sprite memory decays unless you refresh the memory by reading and writing it.
typically rendering reads and writes it, but that doesn't happen when rendering is off
weird shit like this is something a well program game doesn't depend on, and is hardly part of any hardware spec, but it's the behavior of produced consoles, so some autists want to emulate that kind of behavior.
personally, i'm of the opinion that this kind of stuff is out of spec and therefore an implementation bug that could easily be addressed in hardware revisions without changing software compatibility, so not worth trying to emulate or recreate