Minor enhancements (or my personal QoL nitpicks, sorry)

1F --> FF lines in instrument pattern, FFF --> FFFF possible rows in song, 255 --> 2047 max rate, F/F --> FF/FF slowest speed, 2 or more effect columns (like it is done in FamiTracker, so since we are using custom .kt files we don't need to strictly follow old standards particularly there and remain backwards compatibility), two variants for sawtooth (for some fast switching between them and triangle, if I'm not mistaken it is possible on C64):

this

and this

In sample generator: volume, note and filters for each oscillator.