Another important element to the portability of computers was shrinking down the size of the floppy disks drives. Prior to the development of the 5 1/4 inch disk drive, there were no portable computers on the market. As systems matured, smaller disks drives began to appear on the market but there was no clear cut standard size, The journalists argued long and hard over which was the "best" of the "shirt pocket disks", and therefore which one would "obviously" win out. Computer manufacturer, George Morrow suggested that the computer industry should cut a deal with the clothing industry to make shirt pockets 5,25".
Dysan, who was the foremost diskette manufacturer, did not like the 3" and 3,5" designs, since that would require MAJOR retooling. So they came out with the 3.25", which was simply a smaller version of a 5.25", and would require MUCH less re-tooling to produce in their existing factories. But how could they influence the outcome and become the "standard"?
George Morrow (with his own Yogi Berra quote) said that standards are great - everyone should have a unique one of their own! Dysan "knew" that whichever one had software distributed on it would become the standard. So they bet the company on a daring venture. They started a software publishing business! They went around to the larger software companies and cut distribution deals. For a while, you could buy ANY major program on 3,25" diskette!
However, the Seequa Chameleon 325 was one of the only machines that used a 3.25" drive, and they are very rare. Everybody else waited to see what everybody else would do. The inertia kept the critical mass from ever coming about. There were a lot of 3.25" drives and diskettes made. In fact, many more than the computers that used them, Unfortunately for Dysan, standard drives became 3 .50 " and Dysan never completely recovered.
Meanwhile, Amstrad went with the 3" diskette and. Amdek marketed an external 3" drive unit for use with Apple Ile and Radio Shack "Coco" (color Computer). The earliest models of the Gavilan used 3". Also that some Japanese models of the Canon used the 3" drives, Later on, there was a similar baffle between 3 or 4 different 2.5" and 2.3" formats.
IBM showed a 3.9" disk drive at trade shows, but apparently never got around to selling any. But when Hewlett Packard (HP), Apple, and then IBM went with 3.5", the "standard" was set and the others were doomed, and it became clear that technological superiority was NOT necessarily the controlling factor of what would win out.
RICM notes that there have been some minor changes in the 3.5" diskettes. The earliest ones were without shutters. Then there was a "manual" shutter that you had to slide open and closed. Then a semi-automatic one that you had to slide open, and you pinched the corner to release a latch to let a spring close the shutter. You can tell these diskettes by looking for the word "pinch" on some of them. Many current diskettes still have a vestigial arrow pointing to which corner you had to pinch, although now that arrow is purportedly to tell you which end of the diskette to put into the drive 1.