I haven't personally used an SSM control, so take whatever I say about it as possibly incorrect. I am familiar with Hurco controls otherwise.
Firstly, IIRC it's an acronym for "Single Screen Max", and is basically the same as whatever equivalent ultimax/winmax control of the same age, just doesn't have a separate screen for graphics so you have to switch between them.
With that in mind, it almost certainly can run some variant of gcode* and will have rs232, maybe even ethernet which I think was an option at that time.
Year 2000 puts it in the Ultimax 4 era, which is a relatively modern dos pc based control, so there is likely a decent amount of memory and a hard drive, so you shouldn't be running up against memory constraints like you would be with a similar aged Fanuc for example.
*There is effectively two gcode modes on the Hurco, BNC (Basic NC) and ISNC (Industry Standard NC). The latter is effectively a Fanuc M control compatible system, but it is/was an option. BNC was first implemented on early Hurco controls in the '80's as a means to run cam generated programs on the Hurco control. It has no programming aids/shortcuts/advanced cycles and is not intended for hand programming, and some of the codes and conventions might be a little different to what you are used to. It's perfectly functional with a good post however.