For the NTSC NES, the CPU speed is 1789772.7272727272727Hz (exactly 1/2 NTSC colorburst, which is 3.5795454545454545).

For PAL, the CPU speed is 1662607Hz. Yes, it's slower than the NTSC CPU; this is why sound in PAL games is off-pitch when played in an NTSC NES (and vice-versa).

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Quietust
P.S. If you don't get this note, let me know and I'll write you another.