Jim,
It uses a common 3.58MHz crystal for
accuracy,
As I recall, the worst part of
the design was in keeping the timing
straight for the interlaced fields (each field is off by half a
horizontal
period from the one previous).
I did something like this as well, this part of the design was very
simple. All I had to do was to generate a PWM at the 2*HSync, count an
even number of such pulses (2*NumberOfLinesBetweenVSync) For VSync
generation and then divide that it by 2 to get a real HSync.
Also, I used a crystal that was not standard 16,111,616 Hz (custom made).
Chaipi