Microsoft Windows 8.1 All in One 32/64-bit ISO is a comprehensive installation media that contains all the editions of Windows 8.1, including 32-bit and 64-bit versions. This all-in-one ISO file allows users to install any edition of Windows 8.1, including Windows 8.1, Windows 8.1 Pro, Windows 8.1 Enterprise, and Windows 8.1 RT.