What operating system options are available?

The HP ProBook 450 G3 supports multiple operating systems: Windows 10 Pro 64-bit, Windows 10 Home 64-bit, Windows 8.1 Pro 64-bit, Windows 8.1 64-bit, Windows 7 Professional 64-bit (available through downgrade rights from Windows 10 Pro 64), and FreeDOS 2.0. Note that only one version of Windows can be used at a time, and switching between versions requires uninstalling one and installing the other with data backup.