If you're still intrigued, read on for a deep dive into the background of the problem and my proposed solutions. No stone was left unturned, no area left unfinished. I want this final piece solved so that I can feel confident in my retirement that the SNES has been faithfully and completely preserved through emulation. I'm getting older, and I won't be around forever. I can tell you why this is important to me: it's my life's work, and I don't want to have to say I came this close to finishing without getting the last piece of it right.
As with any goal in life, the closer we get to perfection, the smaller the returns. If you're not interested in the pursuit of one hundred percent faithful emulation perfection for its own sake, I am not going to be able to convince you of the need for improving SNES PPU emulation further. The remaining issues are relatively small ones, in the grand scheme of things. We mostly know how the PPUs work, but we have to make guesses for some functionality that result in less than total perfection. The sole exception is the PPUs (picture processing units), which are used to generate the video frames sent to your screen. Today, we enjoy cycle-level accuracy for nearly every component of the SNES. So that's it, right? Kudos on a job well done, thanks for all the fish? Well.
Further Reading Accuracy takes power: one man’s 3GHz quest to build a perfect SNES emulatorAs the lead coder of bsnes, I've been attempting to perfect Super Nintendo emulation for the past 15 years.