OpenVMS logo Swoosh 30 lg.jpg
OpenVMS V7.3-1 running the CDE-based DECwindows GUI
DeveloperDigital Equipment Corporation, Compaq, Hewlett-Packard, VMS Software Inc
Written inBLISS, VAX Macro, C, Ada, PL/I, Fortran, UIL, SDL, Pascal, MDL, C++, DCL, Message, Document[1]
OS familyDEC OS family
Working stateCurrent
Source modelClosed source
Initial releaseOctober 25, 1977; 40 years ago (1977-10-25)
Latest releaseOpenVMS 8.4-2L2 / July 10, 2017; 14 months ago (2017-07-10)
Marketing targetHigh-end computer server
Available inEnglish
Update methodConcurrent upgrades,
rolling upgrades
Package managerPCSI and VMSINSTAL
PlatformsVAX, Alpha, Itanium
Kernel typeMonolithic kernel with loadable modules
Default user interfaceDCL CLI and DECwindows GUI

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.[2][3][4] 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.[5] As of 2018, a port to the x86-64 architecture is underway.[6][7]

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.[8]

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.[2]

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[9] 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[10] 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).[11][12] VMS Software will be responsible for developing OpenVMS, supporting existing hardware and providing roadmap to clients.[11][12] The company has a team of veteran developers that originally developed the software during DEC's ownership.[13]


Origin and name changes

VAXstation 4000 model 96 running OpenVMS 6.1 and DECwindows

In April 1975, Digital Equipment Corporation embarked on a hardware project, code named Star, to design a 32-bit virtual address extension to its PDP-11 computer line. A companion software project, code named Starlet, was started in June 1975 to develop a totally new operating system, based on RSX-11M, for the Star family of processors. These two projects were tightly integrated from the beginning. Gordon Bell[14] was the VP lead on the VAX hardware and its architecture. Roger Gourd was the project lead for the Starlet program, with software engineers Dave Cutler (who would later lead development of Microsoft's Windows NT), Dick Hustvedt, and Peter Lipman acting as the technical project leaders, each having responsibility for a different area of the operating system. The Star and Starlet projects culminated in the VAX 11/780 computer and the VAX-11/VMS operating system. The Starlet name survived in VMS as a name of several of the main system libraries, including STARLET.OLB and STARLET.MLB.

Over the years the name of the product has changed. In 1980 it was renamed, with version 2.0 release, to VAX/VMS (at the same time as the VAX-11 computer was renamed to simply VAX). With the introduction of the MicroVAX range such as the MicroVAX I, MicroVAX II and MicroVAX 2000 in the mid-to-late 1980s, DIGITAL released MicroVMS versions specifically targeted for these platforms which had much more limited memory and disk capacity; e.g. the smallest MicroVAX 2000 had a 40MB RD32 hard disk and a maximum of 6MB of RAM, and its CPU had to emulate some of the VAX floating point instructions in software. MicroVMS kits were released for VAX/VMS 4.4 to 4.7 on TK50 tapes and RX50 floppy disks, but discontinued with VAX/VMS 5.0.

In 1991,[15] VMS was renamed to OpenVMS as an indication for its support of "open systems" industry standards such as POSIX and Unix compatibility,[16] and to drop the hardware connection as the port to DIGITAL's 64-bit Alpha RISC processor was in process. The OpenVMS name first appeared after the version 5.4-2 release.

Port to DEC Alpha

Old logo

The VMS port to Alpha resulted in the creation of a second and separate source code libraries (based on a source code management tool known as VDE) for the VAX 32-bit source code library and a second and new source code library for the Alpha (and the subsequent Itanium port) 64-bit architectures. 1992 saw the release of the first version of OpenVMS for Alpha AXP systems, designated OpenVMS AXP V1.0. The decision to use the 1.x version numbering stream for the pre-production quality releases of OpenVMS AXP caused confusion for some customers and was not repeated in the next platform port to the Itanium.

In 1994, with the release of OpenVMS version 6.1, feature (and version number) parity between the VAX and Alpha variants was achieved. This was the so-called Functional Equivalence[17] release, in the marketing materials of the time. Some features were missing however, e.g. based shareable images, which were implemented in later versions. Subsequent version numberings for the VAX and Alpha variants of the product have remained consistent through V7.3, though Alpha subsequently diverged with the availability of the V8.2 and V8.3 releases.[18][19]

In November 2017, V8.4-2L1 was released for Alpha platform (or x86 emulator).[20]

Port to Intel Itanium

In 2001, just prior to its acquisition by Hewlett-Packard, Compaq announced the port of OpenVMS to the Intel Itanium architecture.[21] This port was accomplished using source code maintained in common within the OpenVMS Alpha source code library, with conditional and additional modules where changes specific to Itanium were required. The OpenVMS Alpha pool was chosen as the basis of the port as it was significantly more portable than the original OpenVMS VAX source code, and because the Alpha source code pool was already fully 64-bit capable (unlike the VAX source code pool). With the Alpha port, many of the VAX hardware-specific dependencies had been previously moved into the Alpha SRM firmware for OpenVMS. Features necessary for OpenVMS were then moved from SRM into OpenVMS I64 as part of the Itanium port.[22]

Unlike the port from VAX to Alpha, in which a snapshot of the VAX code base circa V5.4-2[17] was used as the basis for the Alpha release and the 64-bit source code pool then diverged, the OpenVMS Alpha and I64 (Itanium) versions of OpenVMS are built and maintained using a common source code library and common tools. The core software source code control system used for OpenVMS is the VMS Development Environment (VDE).[23]

Two pre-production releases, OpenVMS I64 V8.0 and V8.1, were available on June 30, 2003 and on December 18, 2003. These releases were intended for HP organizations and third-party vendors involved with porting software packages to OpenVMS I64.

The following are recent OpenVMS I64 releases:

  • OpenVMS I64 V8.2, the first production-quality Itanium release, was shipped January 13, 2005. A V8.2 release is also available for Alpha platforms.
  • OpenVMS I64 V8.2-1, adding support for Integrity Superdome and cell based systems, was released in September 2005. V8.2-1 is available for Itanium platforms only.
  • OpenVMS I64 V8.3, was released for Itanium platforms in September 2006. V8.3 is also available for Alpha systems.
  • OpenVMS I64 V8.3-1H1, was released in October 2007. It features full c-Class Integrity BladeServer blade support.[24]
  • OpenVMS I64 and Alpha V8.4, was released in June 2010.[25]
  • OpenVMS I64 V8.4-1H1, was released in June 2015.[26]
  • OpenVMS I64 V8.4-2, was released in April 2016; and a variant of it V8.4-2L1 was also released for Alpha platform (or x86 emulator) in November 2017.[20]

Major release timeline

Version[27] Release date[28] End-of-life date[29] Notes
Old version, no longer supported: V1.0 25 October 1977 ? VAX-11/780, Initial commercial release
Old version, no longer supported: V2.0 April 1980 ? VAX-11/750
Old version, no longer supported: V3.0 April 1982 ? VAX-11/730
Old version, no longer supported: V4.0 September 1984 ? VAX 8600 and MicroVMS (for MicroVAX)
Old version, no longer supported: V5.0 April 1988 ? VAX 6000
Old version, no longer supported: V1.0 AXP November 1992 ? first OpenVMS AXP (Alpha) specific version
Old version, no longer supported: V6.0 June 1993 31 December 2012 VAX 7000 and 10000
Old version, no longer supported: V6.1 April 1994 ? merging of VAX and Alpha AXP version numbers
Old version, no longer supported: V7.0 January 1996 ? full 64-bit virtual addressing on Alpha
Old version, no longer supported: V7.3 June 2001 31 December 2012 Last release for the VAX architecture.
Old version, no longer supported: V8.0 June 2003 ? limited availability eval for Integrity
Old version, no longer supported: V8.2 February 2005 30 April 2014 Common Alpha and Itanium release
Old version, no longer supported: V8.3 September 2006 31 December 2015 Alpha, Itanium dual-core support
Older version, yet still supported: V8.4 June 2010 Q4 2020 Virtual machine guest under HPVM. Clusters over TCP/IP
Older version, yet still supported: V8.4-1H1 June 2015 Q4 2020 Support for "Poulson" Itanium processors, first release from VSI
Current stable version: V8.4-2 April 2016 Q2 2021 Support for systems with up to 64 cores and 1.5TB of RAM[30]
Future release: V8.5 Q1 2019 N/A Alpha and Itanium Updates, new TCP/IP stack
Future release: V9.0 Q1 2019 N/A x86-64 Early Adopter Release
Future release: V9.1 Q4 2019 N/A x86-64 General Early Adopter Release
Future release: V9.2 2020 N/A Alpha, Itanium, x86-64 General Release
Old version
Older version, still supported
Latest version
Latest preview version
Future release
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