NTSC/PAL video generating

[Multijointed Monster Maker]

Do I have this correct? The NES, TurboGrafx-16, and SNES use 21-Mhz video signal generating. There are 1024 cycles across the visible screen. One colorburst takes about 6 cycles, where as a pixel takes 4. On the NES, there are 12 color phases because 6 are generated from the 21-Mhz signal, and the other 6 are generated from an inversed 21-Mhz signal. The Sega Genesis uses 54-Mhz video signal generating. There are 2560 cycles across the video screen. One colorburst is 15 cycles, and one pixel is 8 cycles in 320-pixel mode and 10 cycles in 256-pixel mode.

 

Okay now here's what I don't know but want to know. How does the Turbografx-16 do those high resolutions like 352? How does the Turbografx Snes and Genesis convert RGB to NTSC/PAL? Something tells me it has something to do with red green and blue being almost exactly 60-degrees apart in colorphase.