The computer used removable media: 12" removable "Diablo" 5MB hard drive platters. One had four user basic on it, one had single user basic, and one was locked away with the software for grading students.
Memory management was primitive: BASIC ran in RAM, and if you used single user basic, you had 4x the RAM and therefore room for 4x the program. When swapping drives, you had to boot the computer by toggling the CPU's three instructions into the front panel.
I wrote a massive Star Trek adventure game in single user basic. Friends would actually creep into the lab overnight so they could play by themselves.