You mean the times of Aix, Solaris, HP-UX, NeXT, Mac OS, Amiga OS, Atari ST, Acorn, BeOS,AS/400, z/OS, Psion, Palm Pilot, Atari Portolio, Newton, ...?
Already your assessment regarding AIX being dead, when it is one of survivors from UNIX/Linux wars shows how your Microsoft hate blinds your judgement.