"Two years later, IBM introduced the 3½-inch floppy disk that featured 1.44 megabytes of storage space and a plastic case surrounding the internal disk, a format that became the mainstay of computing in the 1990s. The 3½-inch disks were more compact and had higher storage capacity, and the rigid case provided better protection."

The article makes it sound that way, but it was Sony who introduced 3.5" drives (IBM, later, increased the density).

The whole article is rather IBM and Floppy biased, going as far as implying that Floppys enabled the Software Industry. Why the propaganda for a dead medium?

Its all IBM PR :) 3 1/4 was Japan, HD drives was Japan, ED drives was Japan, TD drives was Japan. Cheap two head drives was afaik Tandon, IBM had an elaborate expensive and complicated mechanism moving both heads while Tandon decided to keep bottom head stationary. IBM cross licensed patents with Tandon when they made a deal to ship Tandon TM-100-2A floppies in PCs.