Dean,

thanks for the great input, cleared some clouds :-) , but still my question stands:

Mach3 outputs normally 25khz pulse. On a perfect PC it could output stable 100kHz /or even up to 300kHz before it locks, on a top computer, according to its creators/ .

Now, how these 100kz become 1Mhz or 4Mhz on CSMIO, Galil or whatsoever when mach3 outputs only pulses, not trajectory information. They generate them, the same way a geared servo drive generates them, so in fact - no real resolution benefit at all with expensive boards for the $$$, coupled with servos, steppers and Mach3. Apart from the reliability , ethernet or usb connection and I/O. It seems to me that these Mhz they are offering are a hype. No body can prove to me that a generated signal from a BOB is better from the same signal generated from a Panasonic servo drive electronically geared, for example.

Dont ask me who put this in my head :-) but now i have it clear after that digging, it took me a week to wake up from the hype- until Mach3 or 4 or.. closes the loop at the PC and transmits trajectory signal to the motion control, i wouldn't care for the Mhz of the boards. It wouldnt happen on windows, except on some kind of dedicated hardware pc probably.

That investigation answered the other questions of mine, why the good DSP motion control cards have + encoder inputs, / not only for Analog servo drives i mean/ . And why a separate dedicated motion control solution for a machine is so darn expensive.

Now seems Linux a kind of do that what we are speaking of. Wow, i am starting to defend Linux