MS-DOS, IBM-DOS, and other DOS derivatives were ... It has some more modern features, like a package manager and a live CD image. There are also ported versions of modern utilities, like Vim ...

To get the answer, just put a decimal point in the number "50"—my first Microsoft product was MS-DOS 5.0.

It’s interesting that they would preserve what’s arguably the least popular version of MS-DOS in this way, but then again there’s something to be said for having a historical record on what ...