It was 95 that was the first desktop version to see the optical disk used namely the cd when the early 1x and 1x/2x cd rom drives were first seen available. Before that "everything" was either on 3 1/2" or 5 1/4" as far as softwares as well as the version of Windows.
For someone who never seen and ran one of the older versions and may want to learn something about Linux with a console and Bash commands there a good run of a manually started OS at a dos prompt can be a valuable lesson! "egads! a dos prompt and typing win.exe manually and pressing the enter/return key!