OpenVMS is a closed-source, proprietary 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, and first released in 1977 for its series of VAX-11 minicomputers. The 11/780 was introduced at DEC's Oct. 25, 1977 annual shareholder's meeting. In the 1990s, it was used for the successor series of DEC Alpha systems. OpenVMS also runs on the HP Itanium-based families of computers. As of 2019, a port to the x86-64 architecture is underway.The name VMS is derived from virtual memory system, according to one of its principal architectural features. OpenVMS is a proprietary operating system, but source code listings are available for purchase.OpenVMS is a multi-user, multiprocessing virtual memory-based operating system (OS) designed for use in time-sharing, batch processing, and transaction processing. When process priorities are suitably adjusted, it may approach real-time operating system characteristics. The system offers high availability through clustering and the ability to distribute the system over multiple physical machines. This allows the system to be tolerant against disasters that may disable individual data-processing facilities.OpenVMS contains a graphical user interface (GUI), a feature that was not available on the original VAX-11/VMS system. Prior to the introduction of DEC VAXstation systems in the 1980s, the operating system was used and managed from text-based terminals, such as the VT100, which provide serial data communications and screen-oriented display features. Versions of VMS running on DEC Alpha workstations in the 1990s supported OpenGL and Accelerated Graphics Port (AGP) graphics adapters.
Enterprise-class environments typically select and use OpenVMS for various purposes including mail servers, network services, manufacturing or transportation control and monitoring, critical applications and databases, and particularly environments where system uptime and data access is critical. System up-times of more than 10 years have been reported, and features such as rolling upgrades and clustering allow clustered applications and data to remain continuously accessible while operating system software and hardware maintenance and upgrades are performed, or when a whole data center is destroyed. Customers using OpenVMS include banks and financial services, hospitals and healthcare, network information services, and large-scale industrial manufacturers of various products.
As of mid-2014, Hewlett-Packard (successor to DEC) licensed the development of OpenVMS exclusively to VMS Software Inc. (VSI). VMS Software will be responsible for developing OpenVMS, supporting existing hardware and providing roadmap to clients. The company has a team of veteran developers that originally developed the software during DEC's ownership.