Control Data Corporation Magnetic Peripherals division used to make removable hard disks (844’s) and 885’s for all the mainframe vendors. Magnetic Peripherals became Imprimis and was sold to Seagate.
You’ve see a Control Data mainframe I bet. They had one in the Nokitome Plaza in Die Hard 1, and I think (someone will correct me on this) they had one in Jurassic Park.
I worked on the OS for the 6000 series (Scope 3.3-3.4 and NOS/BE), 170 series (NOS/BE and NOS), the 7600 (Scope 2), 800 series (NOS and NOS/VE), 900 series (NOS/VE) and some of the really fast (for their time) specialized parallel processor systems CDC made (AFP, CyberPlus, and micro AFP). Never got to work on the ETA (liquid nitrogen or air cooled), but I saw one once. My languages were Compass (CP and PP), MICA, Fortran (Run and FTN), COBOL, and C. I also knew ALGOL and IBM assembly language from college. No Pascal...
Correction on the 900 series - that was IRIX (UNIX). The 900s were Silicon Graphics workstations with CDC skins on them.