> Is the 15kHz RGB signal fundamentally the same as the VGA signal, except > at a lower horizontal frequency? If not, how do they differ?
Basically, yes. 3 separate analogue video signals, one for each primary colour. The drifference might be the sync signals. VGA has two, basically think of them as one to start a new scan line (horizontal sync), the other to start a new field (vertical sync). Often analogue RGB as a combined (or composite) sync, which is normally the logical XOR of the 2 separate sync signals. Since they are of very different frequencies, they can be separated again in the monitor. There is also 'sync on green'. In this one the sync signals are combined with the green video signal to make something similar to a monchrome composite video signal. With separate red and blue signals. -tony
