Originally posted by vinzer I'm of the assumption that data readout speed has more to do with the supporting electronics than the sensor itself. I guess I'm wrong about it.
It's both. You have the same limitations w/ flash memory and regular DRAM computer memory. You can only do it so fast and add so many parallel paths before you run out of pins or make it too expensive (each parallel path adds more cells, takes up space, uses pins, etc.). Chip design as in most things in life is a set of tradeoffs (used to do it for my 1st career)...
The reason the K20D can only do 20fps is because of sensor readout speed as well AFAIK. Probably the same w/ the new Canon Rebel Ti1 which can only do 20fps HD video...