From The Free On-line Dictionary of Computing (8 July 2008) [foldoc]:
Virtual Memory System
OpenVMS
VAX/VMS
VMS
<operating 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://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)
From Jargon File (4.4.4, 14 Aug 2003) [jargon]:
VMS
/V.M.S/, n.
DEC's proprietary operating system for its VAX minicomputer; one
of the seven or so environments that loom largest in hacker folklore.
Many Unix fans generously concede that VMS would probably be the
hacker's favorite commercial OS if Unix didn't exist; though true,
this makes VMS fans furious. One major hacker gripe with VMS concerns
its slowness -- thus the following limerick:
There once was a system called VMS
Of cycles by no means abstemious.
It's chock-full of hacks
And runs on a VAX
And makes my poor stomach all squeamious.
-- The Great Quux
See also VAX, TOPS-10, TOPS-20, Unix, runic.