This is a copy of an email I sent to a fellow collector, regarding what to do at the plus prompt ( + ) upon successful boot of a Nortstar Horizon computer, using Northstar DOS. Here is my answer:
I assume you have two working drives, if not stop and contact me. I am not sure how much you know about the N*, they're sometimes cryptic to follow. See if you can find a copy of the North Start System Software Manual.
+ means from the N* DOS prompt
> means from the N* monitor (I assume you know what a monitor is) if you find yourself at this prompt the command OS will return you to N* DOS.
drive 1 = left drive
drive 2 = right drive
+GO CD [enter] (follow the prompts)
+GO CF[enter] (follow the prompts)
CD means copy diskette
CF means copy file
+GO CF ABC ABC1 (copy the file ABC to ABC1)
+LI 1 [enter] (what's on the left drive?)
+LI 2 [enter] (what's on the right drive?)
+GO BASIC [enter] (load basic)
+IN 1 D [enter] (initialize a disk in drive 1 using double density S=Single D=Double)
+GO DOS [enter] (I think this will reboot the system)
+GO DT 1 [enter] (disk test program, test drive 1)
There's a lot more, especially using the monitor - GO M2D00 [enter]....if questions, just ask.