On: The 25¢ Apple II Real Time Clock (1981)

[Zardoz84]

NTSC uses 30 FPS because it's half of it. The same reason is why PAL uses 25fps as on Europe we have 50 Hz on the grid

[Taniwha → Zardoz84]

well technically they use this to reduce hum based interference (the alternative is a slowly rolling hum bar through the screen)