MS DOS 5.0

"This 3 disk set on 3.5 inch floppy disks is the entire operating system from a personal computer in the 1990's. Each disk contained 1.4 megabytes of data. Its initial release date in 1991 predated the graphical user interface of Windows 3.1. However, Windows 3.1 was not a full operating system but piggy backed onto DOS."