old Nc_router vs PC

I have an old CNC-machine witch is connected to a PC. The program is from 1989, and my task is to change the PC to a newer one.
After many hours an tears the new PC and the machine finely get connected by COM1 serialport. The only problem is that the machine doesn´t behave as it should, it seams lost and confused. Signal problem, or something with with that the new computer is too new?? CPU speed? I have tryed everything I can think of.

There is one line inside the mainprogram itself that shows the port. "COM1,9600,E,7,2,RS,CS0,DS0,CD0
Whitch tell me this: bits9600,parityEven,databits7,stopbits2, the last four I don´t know what they means.

The old PC who works just fine is a Compaq Presario 425, with 25MHz I believe. And the program runs in dos 6.22

The "new is about 100MHz", therefor I tried to run the program in dosbox" but I get the same results.
Also when I try to run the program directly from DOS It is the same problem.
It doesn't sound to me like your question has anything to do with Igor Pro.