You might be more successful if you try posting a new thread.
No one else is answering so I will try to help with the little that I know.
First, I have never communicated with any of these machines through a rs232.
This control is pretty much the same as the EZPath and the EZtrak. These controls are basically an old 486 computer that is running dos 6.2. (if they haven't upgraded, they probably have an older version of dos) The EZtrak mill three axis has the ability to actually drip feed. From what I can tell the lathes and the two axis EZtrak can not, but you can transfer a program to the hard drive on all of these machines through the rs232 port. Then you could load it and run it.
I guess the manufacturer at that time thought that you wouldn't need to run a program over 256K (the capacity of the buffer) on a two axis mill or lathe.
I have included an attachment I scanned out of my PowerPath manual that may help you out. From what I can see it would be similar to transferring a program through a serial port on an old dos PC as you would before windows came on the scene.
If you do get it figured out, could you let me know? I have very seldom had to run a program larger than the capacity of a floppy but I would like to know how it's done.
Pete