SVR UNIXes like HP-UX, Solaris and IRIX were very consistent (I used all three of them simultaneously): if one understood SVR4, one could move between those thr

SVR UNIXes like HP-UX, Solaris and IRIX were very consistent (I used all three of them simultaneously): if one understood SVR4, one could move between those three seamlessly. DEC UNIX, OSF/1 and Ultrix were a variation of BSD. If one knew that, there was no problem either. No comment on AIX, since my brush-ins with it were far too short to be able to claim anything. What else was there? 14 is a large number when it comes to operating systems.