There were a few other, incompatible ones! I remember a cheap word processor with a 2.5" disk with a spiral track!
But, the Zenith (Mini-sport?) was the common one. There were also 2.9"and, of course, for PC there were 3", 3.25", 3.5", and IBM almost came out with a 3.9"!
On Sun, 22 Jan 2023, Chris via cctalk wrote:
You read it right. I think only Zenith and Fujifilm made them.
