Yes, I understand. The point is, with a single oscillator (emphasis, I mean oscillator) being the source of all derived clocks, synchronizing once is sufficient, as all clocks will keep a fixed relation.
If, say, the video card had its own oscillator (comparably how modern video cards do or did), the clock domains would drift from each other and frequent resynchronization were necessary (but you'd just use the interrupt instead that most likely would be added in this scenario).
But I think you helped me understand the scheme. I'd add that according to the article, a single frame is not necessarily enough, given the description on how synchronization can be missed at the first attempt, but this is hardly relevant, given that the synchronization still likely happens only once and within a brief timeframe.
If, say, the video card had its own oscillator (comparably how modern video cards do or did), the clock domains would drift from each other and frequent resynchronization were necessary (but you'd just use the interrupt instead that most likely would be added in this scenario).
But I think you helped me understand the scheme. I'd add that according to the article, a single frame is not necessarily enough, given the description on how synchronization can be missed at the first attempt, but this is hardly relevant, given that the synchronization still likely happens only once and within a brief timeframe.