 Emulation and API-translation projects like Wine and CrossOver make it possible to run non-Linux-based software on Linux systems, either by emulating a proprietary operating system or by translating proprietary API calls (e.g., calls to Microsoft's Win32 or DirectX APIs) into native Linux API calls.A virtual machine can also be used to run a proprietary OS (like Microsoft Windows) on top of Linux.Computer hardware is usually sold with an operating system other than Linux already installed by the original equipment manufacturer (OEM).