La fuente es el manual de Sidwizard 1.7 de Hermit. Aplica tanto para SID de Commodore 64 como para Amiga MOD manteniendo los bpm en 125 (el standard). En el caso de Amiga MOD solo prestarle atención a la fórmula PAL ya que no existen .mod para norma NTSC.
If you are going to use your SID-tunes in a DAW like Cubase for further processing you probably want to know the tempo of your tune in beats per minute. You can use the calculation below. If you don’t care where the values come from, just use the final formulas for your PAL or NTSC machine. (The second one is simplified but should give you an exact enough tempo value since you can rarely insert a tempo with more than two decimals.)
Variables from your tune are song tempo and pattern lines per beat. If you have a tune with funktempo then you calculate the mean value of the two tempos, so for a funktempo of 0604 you would use 5 in the calculation.
PAL MACHINE
Base clock 17734475 Hz
System clock Base clock / 18
Raster lines / frame 312
Clock cycles / raster line 63
Clock cycles / frame 312*63
Frames per second 17734475 / (312*63*18) = 50.125 Hz
Frames per minute (17734475*60) / (312*63*18)
Final formula (PAL):
BPM = (17734475*60) / (312*63*18*song tempo*lines per beat)
BPM ≈ 3007.4744 / (song tempo*lines per beat)
NTSC MACHINE
Base clock 14318180 Hz
System clock Base clock / 14
Raster lines / frame 63
Clock cycles / raster line 65
Clock cycles / frame 263*65
Frames per second 14318180 / (263*65*14) = 59.826 Hz
Frames per minute (14318180*60) / (263*65*14)
Final formula (NTSC):
BPM = (14318180*60) / (263*65*14*song tempo*lines per beat)
BPM ≈ 3589.5659 / (song tempo*lines per beat)