> to reduce flicker with US household mains frequency This isn't the reason for the odd frequencies (and black and white television was exactly 60i). The reaso

> to reduce flicker with US household mains frequency This isn't the reason for the odd frequencies (and black and white television was exactly 60i). The reason for the odd frame-rate is that you need to do some very fancy math to fit the color data in the same analog signal without breaking backwards compatibility.