> The NMI fires at the start of each video frame, which is extremely consistent at 60.0988 Hz
Wouldn’t that be different on a PAL NES? The parent mentioned that they wanted "to keep track of real time [...] regardless of the frame rate, which varied".
It is indeed different on PAL vs NTSC. The code relies on the NMI being called at 50Hz - as a result a number of timings are wrong on the NTSC version, so the music is too fast, the combat demo auto-play doesn't work properly, the time reported for completing the combat demo is wrong, and so on. The NTSC version is unfinished, and this is just one area where it shows.
Wouldn’t that be different on a PAL NES? The parent mentioned that they wanted "to keep track of real time [...] regardless of the frame rate, which varied".