There has been a couple of these machines converted to LinuxCNC and there are build threads on the Linuxcnc forum. There is a much greater range off reasonably priced controller options with LinuxCNC. Pretty sure from what was said they are 0-10 volt analog servos so a Mesa 7i77 will take care of the motion side. Depending on if you want to connect via Ethernet or via PCI/PCIe will determine if you use a 7i92 (ethernet), 5i25 (PCI)or 6i25 (PCIe) to connect it to the PC.