Is anyone here familiar with the old Nortel DMS-100 PBX systems?

Hello,

I've recently been brought in as a L3 network support resource for a very large company that happens to be running with some extremely outdated equipment. One of these pieces of equipment happens to be an ancient PBX system - the Nortel DMS 100. Thankfully it isn't my job to support this, but my coworker - a telecom professional - is stuck with it, and I'm looking for resources to make their life easier.

The problem here is that there has been absolutely no knowledge transfer for this. The company in question has bounced through several managed services contracts throughout the years, and apparently contacting the old MSP is out of the question. The DMS-100 is also, like I said, ancient, so we have no vendor support; and no other industry professionals we've spoken with have a clue how to support this.

If any of you have any resources for supporting these things (documentation, videos, etc) I'd greatly appreciate it if you'd sent them my way! So far, we've managed to come across a command reference, at least, so there's that. But we're running into errors trying to enter several commands and we don't have a clue how to get past them.