Computers would fill a room or even a whole floor when I came to Purdue. Before I left they had shrunk to a desk with the desktop revolution on the horizon.
Some mainframes were modern computers purchased with an eye to the future.
Some mainframes were aging equipment donated to the university as corporations wrote them off.
I recall them in the order I encountered them.
IBM 7094 PUFF student programs in fortran, for both ee and cs classes.
IBM 1620 with disk operating system (a new thing).
IBM 7094 PROCSY macros intended for supervising remote job submission were just powerful enough to write interesting programs.
IBM 1130 in Krannert Business School
RPC 4000 serial cpu with drum memory had crc in the panel for register lights.
DEC PDP-9 with a radar-tube calligraphic display.
CDC 6500 staff programming and graduate school programming on the super computer of the era.
PLATO which was influential even though I never programmed it.
IBM 7094 Console which I programmed without any software using switch registers.
Ramo-Wooldridge 530 in the ee lab brought back to life by Michael Maslied and myself.
Imlac PDS-1 in assembler on ee's machine and fortran on me's machine. Never touched cs's Imlac but did have a demo once.
DEC PDP-11 configured as a lab controller with analog inputs and outputs.