Multicam CSG

I am buying a 1998 Multicam CSG. From the tech I am thinking he said it does not support GCode.. He said it supported some kind of H code. I am pretty sure this is what he said, something about 2D, 2.5D and 3D H code. If someone knows about this, could I get some help. He insisted I am going to need some kind of Win98 machine to run it's proprietary post processor. What is tis H Code he is talking about and why does a Google search not come up with anything?

I was also wondering if I could use something like Mach3 or one of those programs instead of whatever this post processor it needs that runs on Windows 98. I am not sure exactly what Mach3 does though so maybe I am way off. Used a few CNC's before, but they were pre-setup so this is all kinda new to me. So please stick with me and my stupidness :o