All information about that computer is welcome even if it's not related to my problem, since I can't find very much information related to it.
You can say that again. I looked around Google a bit and there is not much at all.
I found info that said the version of NCR System V may be very close to generic AT&T UNIX, and info about recovering provided you already knew the password and have (I assume) the original software tapes (OOS tape?).
What sort of drives does the computer have? Floppy (what size)? CD? Only tape?
How far do you get with bootup? Up to a user prompt? Is info about the software version displayed?