With a capacity of 5 MB, the IBM 350 disk storage unit could have stored about two MP3 files. This photo, showing a unit getting forklifted onto a plane, is from 1956.
IBM's history website has more information about the drive.
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. His new book is Maker Dad: Lunch Box Guitars, Antigravity Jars, and 22 Other Incredibly Cool Father-Daughter DIY Projects