My first computer exposure was on a mainframe (CDC Cyber 180). My university in Kerala, India had a collaboration with the Indian defence organisation DRDO. The operating system was something called NOS/VE, though as I remember it could run some Unix version virtually. I had Fortran 77 programs to be developed as part of the course. (finite element methods). As I remember, the machine had built in routines for the same. Screen was a green on dark terminal conected to the thing. No windowing or graphics.
Today kids have more powerful machines at home (or in their pockets). The famous computing power law be praised.