I'll also add that I've used my mach 3 controller several times with 3D files that have taken 8-9 hours on a medium sized mill cutting Brass and Aluminium at 300mm/min and Mach has never failed mid file.

Steve

Gorilla CNC User,

Adding an additional PCI parallel port wont stop the problem you are having.

What is causing the issue is intentionally built in to the BIOS and operating system.

It is not a matter of a defective P.C. or parallel port

First the BIOS on the motherboard polls the port or interrupts

Secondly Windows also polls the ports and interrupts during startup.

The only solution is to add a charge pump and wire it so the motor drivers are disabled when Mach3 is not running.

Jeff...