What operating systems are supported by the HP EliteDesk 800 35W G2 Desktop Mini PC?

The HP EliteDesk 800 35W G2 Desktop Mini PC supports Windows 10 Pro 64-bit, Windows 10 Home 64-bit, Windows 8.1 Pro 64-bit, Windows 8.1 64-bit, Windows 7 Professional (32-bit and 64-bit, available via downgrade rights), and FreeDOS 2.0. If switching between Windows versions, you must uninstall one version before installing the other, and it is required to back up all data beforehand to avoid data loss. (Page 2)