OpenVMS is an operating system from the Digital Equipment Corporation (DEC) that runs in both its VAX and Alpha computers. OpenVMS evolved from VMS , which originated as the operating system for the VAX in 1979. VMS exploited the concept of virtual memory . DEC is now part of Compaq.
OpenVMS is a multitasking and multiprocessing operating system based on VMS; it was renamed OpenVMS when it was redeveloped for the Alpha processor. (OpenVMS is also the name now used on the VAX computer.) The "Open" suggests the added support for the UNIX-like interfaces of the POSIX standard. Programs written to the POSIX standard, which includes a set of standard C language programming functions, can be ported to any POSIX-supporting computer platform. Formerly a 32-bit operating system, more recent versions of OpenVMS support 64-bit instructions.
Among other features, OpenVMS can be used with special software that facilitates its use with Windows servers.