Twinhead Superset 310

Dear Listers, I'm completely new to this list as well as to vintage PCs and I hope to get some help from you knowledgeable folks in respect to a box I recently got from a friend of mine. It's a Twinhead Superset 310 with a 80286 processor, 1 MB of RAM, a ST-251 harddisk and 5,25" floppy-drive (IBM YD-380) for 1.2 MB disks. The battery was gone, so at every startup, I had to type in the configuration setup. I ONCE only managed to boot the machine which immediately started WordPerfect 5. I typed a few sentences but I could not save this text (the program all the time asking for a floppy I did not have) nor could I end the application or shut down the system (I REALLY do not know anything about DOS). So, I just powered down the machine. Afterwards, I never again managed to boot the PC, as it always asked for a floppy. Meanwhile, I managed to de-solder the 3.6 V battery and I'll look for a replacement. But there are a lot of questions, as I'd really like to learn to get this machine running and as I'd like to handle it: - The mouse-port on the back looks like a P/S2 but its larger in diameter. What standard is this? - There is one ISA-card I do not know what it is for. It has an external connector just looking like a VGA, but the monitor did not work with that. Furthermore, there are two black connectors ("wholes") about the size of an RCA audio in/out. A networking card (BNC)? - Generally: Does somebody know this machine? Somebody has manuals? Best thanks for caring! Steff