it is for communicating with edi's other equipment or a printer?According to Google there's an offline editor that can be downloaded here. No idea if it is legit or full of ransomware. Caveat emptor.
The ethernet port is listed as optional in the manual. There doesn't appear to be any documentation about how to configure an ethernet connection.
Contrary to the standard, EDI made all of the components custom, the ic where the ethernet port lies is custom so it is there for a reason. Also I'm not too concerned about hard drive failure as there is none. Pictures and labels will followThat console is probably based on an off the shelf, industrial computer board with ISA peripherals. The daughter boards are probably for parallel printer ports, the DMX interface, input/output for faders, buttons, and indicators. It might have an external video card, especially since it has the proprietary, remote video on XLR.
Chances are the ethernet jack was just there because off the shelf motherboards came with one. Network printers were rare at the time, and it would not have any printer drivers for a modern one. I doubt that ethernet was used at all for a lighting system in those years.
I suggest not attempting any updates, even if you manage to find one. Performing updates in that era was not painless and reliable as it is now. Without any factory support, you could turn it into a door stop.
I would worry most about a hard drive failure. If you can find new stock of a compatible drive, and a vintage computer and software to do it with, clone the existing drive soon. A hard drive failure is inevitable.
Actually, EDI DID use a LOT of custom/purpose built parts. < one of the cool things about being in Intel Territory.> Used to find MOBO's, daughter boards and slider panel assemblies all the time in electronic surplus stores around town.