A EZTRAK (not prototrak) that was new in 2000 would have a control in a box with a industrial half size mother board. The limiting program size factor is the BMDC. It has a 256K storage buffer. Thus anything bigger requires the ability to DNC.
The 2 axis machines did not DNC. The 3 axis machines could.
Bridgeport was married to EZCAM and Feature Cam and I know their posts worked well. Mastercam would be a wild card (unknown) in this mix.
Also this machines will probably have a DISK on a Chip. A 8 MB solid state device that is used instead of a hard drive. The first generation SX machines booted from a floppy. Either there is something screwed up of you are mistaken what generation this machine is. The floppy or RS232 can be used to transfer programs.
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)