Hi,
I havent seen a milling machine that large in years now
Yes the parallel port can be a pain. I had a flat bed scanner once that used a parallel port, then i 'upgraded' to a 'better' computer (mobo, processor, etc.) and lost the true parallel port. I tried a parallel port card, and the scanner could only run at about one tenth speed, which was far too slow. There seemed to be no way to correct that.
In the original computer with built in P port, it had a setting in the bias, something like "Extended Parallel Port" or something like that (dont remember too well now) and there was nothing like that in the PP card.
I dont know if they improved this or not as that was many many years ago now. I ended up buying another flat bed scanner that turned out to be much faster than the old one anyway. With the CNC machine this would not be possible however.
I can see this is just a matter of the bridge between the software and the parallel port. If the software could be modified, we could design our own parallel port that runs off of just about any other port like USB or even serial. It might be slower that's all.
One thing is for sure, we could make a stand alone parallel port with a PIC or something, that could be driven from just about anything else. But getting the software to comply with the 'anything else' would be the challenge. We may have to make our own software too then. This begs the question, can we get the specs of the CNC machine, ie the protocol it needs from the parallel port to run properly?
Ideally though, i'd like to see the CNC control work from another port, not the parallel port, which has been phased out for the most part now.
Another question that comes up:
What actually does the microstepping? Is it the control board of the CNC, or the software in the PC?
Another option might be to buy a bare bones CNC -- one with motors but no control boards -- and go from there. That way we'd always know what was what and where everything was located.