While ArcInfo was certainly supported on Irix I'd venture a guess and say Erdas Imagine for "heavy lifting" raster. Remote Sensing was such a fun class.
Agreed. Holy cow did I have fun in my remote sensing classes. I'll still remember learning about false color composites from landsat ETM+ data. The first time vegetation just popped out and I was hooked.
My guess is on Erdas Imagine too.
That or some more programmatic stuff like an OGR/GDAL pipeline.