ISTR they had a GUI interface but it was possible to get to a command line somehow. Once I found the command line it didn't take too long to figure out how to get access to other people's accounts (there didn't seem to be any security)
Yours was definitely a later model then. The one I used in 1987 (they disappeared the next year) had only one GUI program - the "UI" program I mentioned. The program was entirely amber on black, but had a toolbar at the top with buttons like "Cut" (with scissors) and "Paste". It was similar to a text editor, but with extra features. From the command line, you couldn't bypass security (at least nobody in the school could) but "UI" obviously didn't follow the security rules. I found UI by spending every lunch checking every folder and subfolder I had access to. After finding UI in an unprotected system subfolder, I used it to snoop everywhere - including the teacher's personal folders. :-D
If it was using an EGA monitor, those were "digital TTL" (you might remember this better from the Radio Shack Tandy line, and I think the C128 equally supported it), so amber was going to be one choice out of a 16-color pallette even on a color display. There's always been the theory that amber or green is easier on the eyes, and either (R+G, or just G) would be a bit less bleary than pure white (R+G+B) on a low-res monitor.
Yep, that's what I thought. So it was 8 or 16-colour, but the OS and most programs were in amber to be easier on the eyes.
When it comes to casings, the Wikipedia article states that some models were made with a detached keyboard... and the pointing device was there because the designers had hoped for a GUI. (That said, lots of '80s-esque workstations included pointing devices just for drawing/CAD or simulation. C64s had joysticks even if you didn't need them for BASIC 2.0. 
)
Mine was definitely the first model. Everybody wondered what the trackball was there for because there was no GUI. Only the "UI" program used it, but I was the only one in the school who found that program. (..and I didn't tell anybody about it :-D)
Now I remember I tried to program my game to use the trackball but nobody knew how to access it. The teacher, and local "computer nerd" (an absolute geek - picture Steven Hawking...without the wheelchair) had no idea how to program for it.
After reading about the lack of software, I now know that everybody played my game at lunch because it was the
only game on the ICON. I thought it was because they thought it was a great game. Damn. (another memory ruined :-( ;-))
