A powerful UNIX operating system that is know for its 3D capabilities, wicked scalability, and number crunching power. It is the OS of choice on such well known systems of the past as the Indy and Indigo, and the modern powerhouses the Origin, Onyx, and Octane.
I only have two real gripes about IRIX. The first is that its security sucks. I mean, you can eventually get things locked-down, but man is it tough. A typical IRIX installation has more holes in it than your average Linux distribution with a swiss cheese sandwich on it. The other thing that is grating my nerves at the moment is it's sucky installation interface. God help you if you ever have to install IRIX on a wiped Indy that only has 1 Gig of disk space with that horrible text based installer. And by text based I mean like at a console, not ncurses or anything. If I never have to type:
conflicts 1a 2a 3a 4a 5a 6a 7a...
ever again, I will be a happy man.
Other than that, IRIX rocks. I love using the Origin2000 here. It is wicked cool...