If the systems in question are based upon the MIPS
R3000, you can also get
IRIX 4.x. That has X (if you really need it). IRIX 3.x used NeWS for the
GUI, which is a very nice windowing system based upon Postscript of all
things.
The old IRIS 31xx series was still Motorola based (68020).
William Donzelli
william(a)ans.net