I was once a supporting sysdamin for HP-UX 10.20 (on HP 9000/725) workstations that were running Mentor Graphics EDA software for designing board layouts. The designers referred to that application as ''Tormentor'' Graphics on bad days, though it was generally great for them. The OS was stable as a rock and never let us down. Not CAD/CAM, but similar purpose.

This is the kind of thing that looks simple until you're three layers deep in edge cases.