Source : Free On-Line Dictionary of Computing

Virtual Memory System
     
         (VMS) {DEC}'s proprietary {operating
        system} originally produced for its {VAX} {minicomputer}.
     
        VMS V1 was released in August 1978.  VMS was renamed "OpenVMS"
        around version 5.5.  The first version of VMS on {DEC Alpha}
        was known as OpenVMS for AXP V1.0, and the correct way to
        refer to the operating system now is OpenVMS for VAX or
        OpenVMS for Alpha.  The renaming also signified the fact that
        the {X/Open} consortium had certified OpenVMS as having a high
        support for {POSIX} standards.
     
        VMS is one of the most secure operating systems on the market
        (making it popular in financial institutions).  It currently
        (October 1997) has the best {clustering} capability (both
        number and distance) and is very scalable with {binaries}
        portable from small desktop {workstations} up to huge
        {mainframes}.
     
        Many {Unix} fans generously concede that VMS would probably be
        the {hacker}'s favourite commercial OS if Unix didn't exist;
        though true, this makes VMS fans furious.
     
        {FAQ
       
     (http://www.cis.ohio-state.edu/hypertext/faq/bngusenet/comp/os/vms/top.html)}.
     
        {Usenet} newsgroup: {news:comp.os.vms}.
     
        [How does its performance compare with other OSes?]
     
        (1999-06-03)