I can tell you that the EZTRAK-SX is the oldest version. It booted from a floppy, had no hard drive, and came with a 286 or 386 processor. Is it still in the original configuration is unknown. It is very possible that parts of the control have been upgraded. The original BMDC board would not allow the current 3rd axis option to be installed. This is not to mean that it is a bad machine. On the contrary, these were very reliable controls. Just be aware that it is a dated control.
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)