Holy cow, I wrote a book!
In case you were wondering.
And those were thirteen of those special Distribution Media Format
floppies, which are specially formatted to hold more data than a
normal 1.44MB floppy disc.
The high-capacity floppies reduced the floppy count by two,
which resulted in a tremendous savings in cost of manufacturing
(I'm sure there are the conspiracy-minded folks who think that DMF
was invented as an anti-piracy measure.
It wasn't; it was a way to reduce the number of floppy disks.
That the disks were difficult to copy was a side-effect,
not a design goal.)
(For comparison, Windows 3.1 came on six floppies.
Windows NT 3.1 came on twenty-two.
And yesterday, one of my colleagues reminded me that Windows NT
setup asked for the floppy disks out of order!
I guess it never occurred to them that they could renumber the disks.)