The Edge of Emulation
> If we latch too late, after cycle 40, Full Throttle Racing will glitch. But if we guess a value too soon, say on cycle 0, that might be too early, and it might cause issues in another game.<p>> We would have to retest the entire SNES library to be sure such a change did not cause any regressions, which just isn't practical with a library of 3,500+ game titles.<p>Running automated regression-tests against a library of known-accurate titles actually sounds extremely practical. This sounds like standard software-engineering practice to me.<p>I'm surprised that a test-harness like this doesn't already exist by now given the relatively mature state of SNES emulation. It seems like it would be an extremely helpful tool to benchmark accuracy of new or existing emulators, prevent regressions from advanced optimizations, etc.<p>Automated testing could transform the 'blind guessing' approach on tweaking PPU timings from a game of 'whack a mole' to a structured, iterative linear algebra solver. Which could end up being quite a bit more feasible than acquiring 100x die scans of the chip and tracing the logic from the hardware directly.