Is Indivision really needed in the 3000, what with the Amber chip allowing you to connect to VGA monitors?
I believe it also allows higher resolution modes to be used. Another feature is that instead of just doubling the scan rate, it can output certain resolutions in a different scan rate. For instance flicker fixed PAL mode can work on LCD monitors that can't handle 50Hz, because it can output that mode in a higher frequency.
At least this is what I gather
