My university was similar (SGI, HP-UX, IBM AIX, Sun, Linux, SCO), but they used NFS to mount home dirs local to the computer clusters, which wasn't as cool because it wasn't possible to mount home dir volumes remotely like an AFS campus. They also, unfortunately, used original NIS which could easily extract all password hashes of all users with a simple `getent passwd`. I proceeded to run John The Ripper against a dump of everyone and found 60 passwords in 30 seconds, including several tenured professors.

Those were the days when portability and longevity were important and there wasn't as much of a monoculture or incompatible code/language features churn.