We were lucky on our site, our team leader was a Stratus guru, and was a great teacher, so we had plenty of time on there if we wanted to practice. We were lucky enough to do just about everything in midrange - Solaris, OpenVMS, Stratus and a bit of Linux here and there in the latter days.
And some ancient lottery processing machines the size of fridges that ran some ancient V7 UNIX variant.
And some ancient lottery processing machines the size of fridges that ran some ancient V7 UNIX variant.