Holy cow, I wrote a book!
In the very early days of Windows 95,
the distribution servers were not particularly powerful.
The load of having the entire team installing the most
recent build when it came out put undue strain on the server.
The solution (until better hardware could be obtained)
was to have a stack of floppy disks in the office of the
(The job of "Build Shepherd" was to perform the initial
diagnosis of problems with the build itself or with verification testing
and make sure the right developer is called in to address the problem.)
If you wanted to install the latest build,
you had to go to the Build Shepherd's office and take one of
the specially-marked floppy disks.
When you finished installing, you returned the disk.
In other words,
the floppy disk acted
as a real-world semaphore token.