text: Whereas earlier versions of Windows are optional `` DOS extending shells '' requiring MS-DOS or an MS-DOS compatible operating system ( usually sold separately ) , Windows 95 incorporated MS-DOS into a consolidated operating system , which was a significant marketing change . The release of Windows 95 also marked wider acceptance of Plug and Play standards on the IBM PC platform .
simplified: Although Windows 95 is thought of as a full operating system , it works over MS-DOS .