I recently asked about an arduino based system but my computer also has the proper port for another system. Am I right in assuming that if I use the port the arduino and its shield is useless? I am guessing that in this case the drivers are driven directly from the PC. Which is better (I will at some point in the future want a 4th axis. thanks
When you say "another system," what do you mean? Your computer doesn't control the machine. The "controller" does. Your computer only communicates with the controller. The controller tells the (stepper) drivers what to do. The Arduino would be the controller. (I'm honestly not sure of what your question is.)
Well my question is what are the benefits and downfalls of using the parallel port versus the USB port.
Since the arduino is a usb device then you are right...you will not be able to use it with the LPT. Here is a discussion about this topic. https://openbuilds.com/threads/usb-vs-parallel-port.705/