OpenVMS is a computer operating system for use in general-purpose computing. It is the successor to the VMS Operating System (VAX-11/VMS, VAX/VMS), that was produced by Digital Equipment Corporation (first released in 1977) for its series of VAX-11 minicomputers and its line of desktop workstations (DEC Alpha). The name VMS is derived from virtual memory system, according to one of its principal architectural features. OpenVMS also runs on the Itanium-based families of computers. OpenVMS is a proprietary operating system (though the source code is available for purchase). Thus, it is not considered open-source software.