Editing OpenVMS (section)

==History==
===Origin and name changes===
[[File:VAX VMS logo.svg|thumb|right|Stylized "VAX/VMS" used by Digital]]

In April 1975, [[Digital Equipment Corporation]] embarked on a project to design a [[32-bit]] extension to its [[PDP-11]] computer line. The hardware component was code named ''Star''; the operating system was code named ''Starlet''. Roger Gourd was the project lead for VMS. Software engineers [[Dave Cutler]], [[Dick Hustvedt]], and Peter Lipman acted as technical project leaders.<ref>{{cite interview |last=Cutler|first=Dave|subject-link=Dave Cutler|interviewer=Grant Saviers|title=Dave Cutler Oral History|url=https://www.youtube.com/watch?v=29RkHH-psrY |archive-url=https://ghostarchive.org/varchive/youtube/20211211/29RkHH-psrY| archive-date=December 11, 2021 |url-status=live|publisher=Computer History Museum|date=February 25, 2016|website=youtube.com|access-date=February 26, 2021}}{{cbignore}}</ref> The Star and Starlet projects culminated in the [[VAX-11#VAX-11/780|VAX-11/780]] computer and the VAX/VMS operating system. The Starlet project's code name survives in VMS in the name of several of the system libraries, including <code>STARLET.OLB</code> and <code>STARLET.MLB</code>.<ref name="what-is-vms" /> VMS was mostly written in [[VAX MACRO]] with some components written in [[BLISS]].<ref name="vms-20-years"/>

One of the original goals for VMS was [[backward compatibility]] with DEC's existing [[RSX-11M]] operating system.<ref name="vms-20-years"/> Prior to the V3.0 release, VAX/VMS included a compatibility layer named the ''RSX Application Migration Executive'' (RSX AME), which allowed user-mode RSX-11M software to be run unmodified on top of VMS.<ref name="vms-1.0-spd" /> The RSX AME played an important role on early versions of VAX/VMS, which used certain RSX-11M user-mode utilities before native VAX versions had been developed.<ref name="vms-20-years"/> By the V3.0 release, all compatibility-mode utilities were replaced with native implementations.<ref>{{cite newsgroup|url=https://comp.os.vms.narkive.com/N4yPsEEV/a-simple-question-what-the-h-ll-is-mcr|title=a simple question: what the h*ll is MCR?|access-date=December 31, 2020|date=September 14, 2004|newsgroup=comp.os.vms}}</ref> In VAX/VMS V4.0, RSX AME was removed from the base system, and replaced with an optional layered product named ''VAX-11 RSX''.<ref>{{cite web|url=http://bitsavers.org/pdf/dec/vax/vms/4.0/AE-DL72A-TE_VAX_RSX_1.0_SPD_198410.pdf|title=Software Product Description VAX-11 RSX, Version 1.0|date=October 1984|publisher=Digital Equipment Corporation|access-date=September 20, 2021}}</ref>

[[File:Vms-albert-cheshire-cat.png|thumb|right|"Albert the [[Cheshire Cat]]" mascot for VAX/VMS, used by the [[DECUS]] VAX SIG<ref>{{cite web|url=http://www.openvmshobbyist.com/forum/viewthread.php?forum_id=130&thread_id=332|title=Hello from....well what used to be SpitBrook|date=February 27, 2007|access-date=January 24, 2021|website=openvmshobbyist.com}}</ref><ref>{{cite web|url=http://www.altiq.se/vax-vms/vax-vms-eng.html|title=Computer system VAX/VMS|website=altiq.se|access-date=January 24, 2021|archive-url=https://web.archive.org/web/20210201143630/http://www.altiq.se/vax-vms/vax-vms-eng.html|archive-date=February 1, 2021|url-status=dead}}</ref>]]

By the early 1980s VAX/VMS was very successful in the market. Although created on [[Unix]] on DEC systems, [[Ingres (database)|Ingres]] ported to VMS believing that doing so was necessary for commercial success. Demand for the VMS version was so much greater that the company neglected the Unix version.<ref name="rdbmsingressybase20070613">{{Cite interview |interviewer=Doug Jerger |title=RDBMS Workshop: Ingres and Sybase |url=https://archive.computerhistory.org/resources/access/text/2013/05/102702565-05-01-acc.pdf |access-date=2025-05-30 |publisher=Computer History Museum |date=2007-06-13}}</ref> A number of distributions of VAX/VMS were created:

* '''MicroVMS''' was a distribution of VAX/VMS designed for [[MicroVAX]] and [[VAXstation]] hardware, which had less memory and disk space than larger VAX systems of the time.<ref>{{cite book |title=Getting Started with OpenVMS: A Guide for New Users |url=https://books.google.com/books?isbn=0080507352  |isbn=978-0080507354 |author=Michael D Duffy |date=2002| publisher=Elsevier }}</ref> MicroVMS split up VAX/VMS into multiple kits, which a customer could use to install a subset of VAX/VMS tailored to their specific requirements.<ref>{{cite news  |newspaper=[[Computerworld]] |date=June 18, 1984 |page=7 |quote=The Micro VMS operating system announced last week by Digital Equipment Corp. for its Microvax I family of microcomputers is a prepackaged version of ... |title=Micro VMS operating system |url=https://books.google.com/books?id=aqjZTUJlyygC}}</ref> MicroVMS releases were produced for each of the V4.x releases of VAX/VMS and was discontinued when VAX/VMS V5.0 was released.<ref name=DEC.prof>{{cite magazine  |magazine=DEC Professional Magazine |title=The VMS/MicroVMS merge |pages=74–84
|author=Kathleen D. Morse}}</ref><ref name="vms-5.0-rel-notes">{{cite web|url=http://bitsavers.trailing-edge.com/pdf/dec/vax/vms/5.0/AA-LB22A-TE_VMS_5.0_Release_Notes_198804.pdf|title=VMS Version 5.0 Release Notes|date=April 1988|publisher=DEC|access-date=July 21, 2021}}</ref>
* '''Desktop-VMS''' was a short-lived distribution of VAX/VMS sold with [[VAXstation]] systems. It consisted of a single [[CD-ROM]] containing a bundle of VMS, DECwindows, DECnet, VAXcluster support, and a setup process designed for non-technical users.<ref>{{cite web|url=http://home.iae.nl/users/pb0aia/vax/dsvs3100.html|title=DECUServe WORKSTATIONS Conference 8|access-date=December 22, 2020|date=January 11, 1989|author=Bob McCormick|website=home.iae.nl|archive-date=July 10, 2022|archive-url=https://web.archive.org/web/20220710024529/http://home.iae.nl/users/pb0aia/vax/dsvs3100.html|url-status=dead}}</ref><ref>{{cite web|url=http://blog.nozell.com/2004/02/office-archeology.html|title=Office Archaeology|date=February 24, 2004|access-date=December 22, 2020|website=blog.nozell.com}}</ref> Desktop-VMS could either be run directly from the CD or could be installed onto a hard drive.<ref>{{cite web|url=http://www.digital.com/info/SP25F4/SP25F4PF.PDF|archive-url=https://web.archive.org/web/20000816181649/http://www.digital.com/info/SP25F4/SP25F4PF.PDF|title=Software Product Description - Desktop-VMS, Version 1.2|publisher=Digital|date=January 1991|archive-date=August 16, 2000|access-date=February 2, 2022}}</ref> Desktop-VMS had its own versioning scheme beginning with V1.0, which corresponded to the V5.x releases of VMS.<ref>{{cite web|url=http://vaxarchive.org/hardware/vms-hw.html|title=OpenVMS pages of proGIS Germany|website=vaxarchive.org|access-date=December 22, 2020}}</ref>
* An unofficial derivative of VAX/VMS named '''MOS VP''' ({{langx|ru|Многофункциональная операционная система с виртуальной памятью, МОС ВП|lit=Multifunctional Operating System with Virtual Memory}})<ref>{{cite web|url=http://oldpc.su/lib/gsp/sm89.pdf|title=Computer Complexes, Technical Equipment, Software And Support Of The System Of Small Electronic Computer Machines (SM Computer)|date=May 1989|language=Russian|publisher=Soviet Union Research Institute of Information and Economics|access-date=October 16, 2021|editor=D.O. Andrievskaya}}</ref> was created in the [[Soviet Union]] during the 1980s for the [[VAX#Clones|SM 1700]] line of VAX clone hardware.<ref>{{cite journal|url=http://www.swsys.ru/index.php?page=article&id=1480#|journal=Software Systems Journal|volume=1988|issue=3|title=Basic software for 32-bit SM computer models|author1=Prokhorov N.L.|author2=Gorskiy V.E.|language=Russian|access-date=October 15, 2021}}</ref><ref>{{cite journal|url=http://www.swsys.ru/index.php?page=article&id=1491#|journal=Software Systems Journal|volume=1988|issue=4|title=Multifunctional operating system that supports virtual memory for 32-bit computers|author1=Egorov G.A.|author2=Ostapenko G.P.|author3=Stolyar N.G.|author4=Shaposhnikov V.A.|language=Russian|access-date=October 15, 2021}}</ref> MOS VP added support for the [[Cyrillic script]] and translated parts of the user interface into Russian.<ref>{{cite web|url=https://mirrors.pdp-11.ru/_vax__/_MOC-32/MOC-32M45/moc-32m-install-1.1.pdf|title=Installing OS MOS-32M|date=June 16, 2012|access-date=October 15, 2021|language=Russian|website=pdp-11.ru|archive-date=October 27, 2021|archive-url=https://web.archive.org/web/20211027181221/https://mirrors.pdp-11.ru/_vax__/_MOC-32/MOC-32M45/moc-32m-install-1.1.pdf|url-status=dead}}</ref> Similar derivatives of MicroVMS known as ''MicroMOS VP'' ({{langx|ru|МикроМОС ВП}}) or ''MOS-32M'' ({{langx|ru|МОС-32М}}) were also created.

With the V5.0 release in April 1988, DEC began to refer to VAX/VMS as simply VMS in its documentation.<ref>{{cite web|url=http://www.bitsavers.org/pdf/dec/vax/vms/5.0/AA-LB22A-TE_VMS_5.0_Release_Notes_198804.pdf|title=VMS Version 5.0 Release Notes|date=April 1988|publisher=Digital Equipment Corporation|access-date=October 27, 2021}}</ref> In July 1992,<ref name=DuffB>{{cite web|url=https://tech-insider.org/vms/research/1992/0715.html|title=Digital Introduces First Generation of OpenVMS Alpha-Ready Systems|publisher=Digital Equipment Corporation|date=July 15, 1992|access-date=January 25, 2021}}</ref> DEC renamed VAX/VMS to OpenVMS as an indication of its support of [[open system (computing)|open systems]] industry standards such as [[POSIX]] and Unix compatibility,<ref name=POSix>{{cite web
|title=OpenVMS Definition from PC Magazine Encyclopedia
|url=https://www.pcmag.com/encyclopedia/term/48503/openvms}}</ref> and to drop the VAX connection since a migration to a different architecture was underway. The OpenVMS name was first used with the OpenVMS AXP V1.0 release in November 1992. DEC began using the OpenVMS VAX name with the V6.0 release in June 1993.<ref>{{cite web|url=http://www.vaxmacro.de/ovmsfaq.html|title=OpenVMS FAQ - What is the difference between VMS and OpenVMS?|author=Arne Vajhøj|date=November 29, 1999|access-date=January 25, 2021|website=vaxmacro.de|archive-date=September 24, 2021|archive-url=https://web.archive.org/web/20210924175454/http://www.vaxmacro.de/ovmsfaq.html|url-status=dead}}</ref>

===Port to Alpha===
{{See also|DEC PRISM#Legacy|DEC Alpha#History}}
[[Image:dec-vms-vernon.png|thumb|"Vernon the Shark" logo for OpenVMS<ref>{{cite web|url=http://www.vaxination.ca/vms/shark/history.html|title=History of the Vernon the VMS shark|website=vaxination.ca|access-date=January 24, 2021}}</ref>]]
During the 1980s, DEC planned to replace the VAX platform and the VMS operating system with the [[DEC PRISM|PRISM]] architecture and the [[DEC MICA|MICA]] operating system.<ref>{{cite web|url=http://www.bitsavers.org/pdf/dec/prism/memos/880530_Cutler_PRISM_vs_MIPS.pdf|title=DECwest/SDT Agenda|author=Dave Cutler|date=May 30, 1988|website=bitsavers.org}}</ref> When these projects were cancelled in 1988, a team was set up to design new VAX/VMS systems of comparable performance to [[RISC]]-based Unix systems.<ref name="supnik-alpha">{{cite web|url=http://simh.trailing-edge.com/semi/ev4.html|title=EV-4 (1992)|date=February 24, 2008}}</ref> After a number of failed attempts to design a faster VAX-compatible processor, the group demonstrated the feasibility of [[porting]] VMS and its applications to a RISC architecture based on PRISM.<ref name="ieee-alpha" /> This led to the creation of the [[DEC Alpha|Alpha]] architecture.<ref>{{cite web|url=https://dspace.mit.edu/bitstream/handle/1721.1/48380/managingtechnolo00katz.pdf|date=April 1993|title=Managing Technological Leaps: A study of DEC's Alpha Design Team}}</ref> The project to port VMS to Alpha began in 1989, and first booted on a prototype [[Alpha 21064#History|Alpha EV3]]-based ''Alpha Demonstration Unit'' in early 1991.<ref name="ieee-alpha">{{cite journal|title=How DEC developed Alpha|date=July 1992|doi=10.1109/6.144508|last1=Comerford|first1=R.|journal=IEEE Spectrum|volume=29|issue=7|pages=26–31}}</ref><ref>{{cite journal|last1=Supnik|first1=Robert M.|title=Digital's Alpha project|journal=Communications of the ACM|volume=36|issue=2|year=1993|pages=30–32|issn=0001-0782|doi=10.1145/151220.151223|s2cid=32694010|doi-access=free}}</ref>

The main challenge in porting VMS to a new architecture was that VMS and the VAX were designed together, meaning that VMS was dependent on certain details of the VAX architecture.<ref name="ia64-port">{{cite journal|url=http://www.decus.de/events/alphamigration/vortraege/porting_openvms_to_integrity.pdf|title=Porting OpenVMS to HP Integrity Servers|author=Clair Grant|journal=OpenVMS Technical Journal|volume=6|date=June 2005}}</ref> Furthermore, a significant amount of the VMS kernel, layered products, and customer-developed applications were implemented in [[VAX MACRO]] assembly code.<ref name="vms-20-years" /> Some of the changes needed to decouple VMS from the VAX architecture included the creation of the ''MACRO-32'' compiler, which treated VAX MACRO as a [[high-level language]], and compiled it to Alpha [[object code]],<ref name="axp-port">{{cite journal|url=https://vmssoftware.com/docs/dtj-v04-04-1992.pdf|title=Porting OpenVMS from VAX to Alpha AXP|author1=Nancy P. Kronenberg|author2=Thomas R. Benson|author3=Wayne M. Cardoza|author4=Ravindran Jagannathan|author5=Benjamin J. Thomas III|journal=Digital Technical Journal|volume=4|issue=4|pages=111–120|year=1992|access-date=April 27, 2024}}</ref> and the emulation of certain low-level details of the VAX architecture in [[PALcode]], such as [[interrupt handling]] and atomic queue instructions.

The VMS port to Alpha resulted in the creation of two separate codebases: one for [[VAX]], and another for Alpha.<ref name="wizard-vms-source">{{cite web|url=http://h41379.www4.hpe.com/wizard/wiz_2993.html|title=Access to OpenVMS Source Code?|work=HP OpenVMS Systems ask the wizard|archive-url=https://web.archive.org/web/20171028043200/http://h41379.www4.hpe.com/wizard/wiz_2993.html|archive-date=October 28, 2017|date=September 2, 1999}}</ref> The Alpha code library was based on a snapshot of the VAX/VMS code base circa V5.4-2.<ref name="OpenVMS VAX and Alpha Compatibility" /> 1992 saw the release of the first version of OpenVMS for [[Alpha AXP]] systems, designated ''OpenVMS AXP V1.0''. In 1994, with the release of OpenVMS V6.1, feature (and version number) parity between the VAX and Alpha variants was achieved; this was the so-called Functional Equivalence release.<ref name="OpenVMS VAX and Alpha Compatibility">{{cite web|url=https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c04623258|title=OpenVMS Compatibility Between VAX and Alpha|date=May 1995|publisher=Digital Equipment Corporation|access-date=October 22, 2021}}</ref> The decision to use the 1.x version numbering stream for the pre-production quality releases of OpenVMS AXP confused some customers, and was not repeated in the subsequent ports of OpenVMS to new platforms.<ref name="ia64-port" />

When VMS was ported to Alpha, it was initially left as a 32-bit only operating system.<ref name="axp-port" /> This was done to ensure backwards compatibility with software written for the 32-bit VAX. 64-bit addressing was first added for Alpha in the V7.0 release.<ref>{{cite journal|url=https://vmssoftware.com/docs/dtj-v08-02-1996.pdf|title=Extending OpenVMS for 64-bit Addressable Virtual Memory|journal=Digital Technical Journal|volume=8|issue=2|date=1996|pages=57–71|s2cid=9618620}}</ref> In order to allow 64-bit code to interoperate with older 32-bit code, OpenVMS does not create a distinction between 32-bit and 64-bit executables, but instead allows for both 32-bit and 64-bit pointers to be used within the same code.<ref>{{cite journal|url=https://pdfs.semanticscholar.org/8d96/bbba019c43e80f059825311b67c975a0fede.pdf|archive-url=https://web.archive.org/web/20200219001633/https://pdfs.semanticscholar.org/8d96/bbba019c43e80f059825311b67c975a0fede.pdf|url-status=dead|archive-date=February 19, 2020|title=The OpenVMS Mixed Pointer Size Environment|journal=Digital Technical Journal|volume=8|issue=2|date=1996|pages=72–82|s2cid=14874367}}</ref> This is known as mixed pointer support. The 64-bit OpenVMS Alpha releases support a maximum virtual address space size of 8TiB (a 43-bit address space), which is the maximum supported by the [[Alpha 21064]] and [[Alpha 21164]].<ref name="prog-concepts-i">{{cite web|url=https://vmssoftware.com/docs/VSI_PROGRAM_CONCEPTS_VOL_I.pdf|title=VSI OpenVMS Programming Concepts Manual, Vol. 1|date=April 2020|access-date=October 7, 2020|publisher=VSI}}</ref>

One of the more noteworthy Alpha-only features of OpenVMS was ''OpenVMS Galaxy'', which allowed the [[Logical partition|partitioning]] of a single SMP server to run multiple instances of OpenVMS. Galaxy supported dynamic resource allocation to running partitions, and the ability to share memory between partitions.<ref name="galaxy-docs">{{cite web|url=https://support.hpe.com/hpesc/public/docDisplay?docId=emr_na-c04621422|title=HP OpenVMS Alpha Partitioning and Galaxy Guide|date=September 2003|publisher=HP|access-date=October 22, 2021}}</ref><ref>{{cite web|url=https://www.arnnet.com.au/article/111492/compaq_details_strategy_openvms/|title=Compaq details strategy for OpenVMS|date=October 14, 1998|access-date=January 14, 2021|author=James Niccolai|publisher=Australian Reseller News|archive-date=April 4, 2023|archive-url=https://web.archive.org/web/20230404095822/https://www.arnnet.com.au/article/111492/compaq_details_strategy_openvms/|url-status=dead}}</ref>

===Port to Intel Itanium===
[[Image:OpenVMS logo Swoosh 30 lg.jpg|thumb|"Swoosh" logo used by HP for OpenVMS]]

In 2001, prior to its acquisition by [[Hewlett-Packard]], [[Compaq]] announced the port of OpenVMS to the [[Intel]] [[Itanium]] architecture.<ref>{{cite web|url=http://h71000.www7.hp.com/openvmstimes/openvmstimes.pdf|title=Compaq OpenVMS Times|date=January 2002|archive-url=https://web.archive.org/web/20060302213751/http://h71000.www7.hp.com/openvmstimes/openvmstimes.pdf|archive-date=March 2, 2006|url-status=dead}}</ref> The Itanium port was the result of Compaq's decision to discontinue future development of the Alpha architecture in favour of adopting the then-new Itanium architecture.<ref>{{cite web|url=https://www.theregister.com/2001/06/25/farewell_then_alpha_hello_compaq/|title=Farewell then, Alpha – Hello, Compaq the Box Shifter
|author=Andrew Orlowski|date=June 25, 2001|access-date=December 21, 2020|website=theregister.com}}</ref> The porting began in late 2001, and the first boot on took place on January 31, 2003.<ref>{{cite newsgroup|url=https://groups.google.com/g/comp.os.vms/c/alWtue7YLUw/m/x1_GVv1eFfEJ|title=OpenVMS Boots on Itanium on Friday Jan 31|date=January 31, 2003|access-date=December 21, 2020|author=Sue Skonetski|newsgroup=comp.os.vms}}</ref> The first boot consisted of booting a minimal system configuration on a [[List of Hewlett-Packard products#Itanium based|HP i2000]] workstation, logging in as the <code>SYSTEM</code> user, and running the <code>DIRECTORY</code> command. The Itanium port of OpenVMS supports specific models and configurations of [[HPE Integrity Servers]].<ref name="vms-8.4-spd" /> The Itanium releases were originally named ''HP OpenVMS Industry Standard 64 for Integrity Servers'', although the names ''OpenVMS I64'' or ''OpenVMS for Integrity Servers'' are more commonly used.<ref>{{cite web|url=https://vmssoftware.com/docs/ig_bvbv.pdf|title=HP C Installation Guide for OpenVMS Industry Standard 64 Systems|date=June 2007|publisher=HP|access-date=March 2, 2021}}</ref>

The Itanium port was accomplished using source code maintained in common within the OpenVMS Alpha source code library, with the addition of conditional code and additional modules where changes specific to Itanium were required.<ref name="ia64-port" /> This required certain architectural dependencies of OpenVMS to be replaced, or emulated in software. Some of the changes included using the [[Extensible Firmware Interface]] (EFI) to boot the operating system,<ref>{{cite web|url=http://www.decus.de/slides/sy2005/06_04/2g04.pdf|title=OpenVMS Integrity Boot Environment|date=2005|access-date=December 21, 2020|author=Thomas Siebold|website=decus.de}}</ref> reimplementing the functionality previously provided by Alpha PALcode inside the kernel,<ref name="swis" /> using new executable file formats ([[Executable and Linkable Format]] and [[DWARF]]),<ref>{{cite web|url=http://www.hp-user-society.de/events/alphamigration/vortraege/porting_openvms_applications_to_itanium.pdf|title=Porting OpenVMS Applications to Itanium|access-date=December 21, 2020|website=hp-user-society.de|date=2005|author=Gaitan D’Antoni}}</ref> and adopting [[IEEE 754]] as the default floating point format.<ref>{{cite web|url=http://www.decus.de/events/alphamigration/vortraege/i64-floating-pt-wp.pdf|title=OpenVMS floating-point arithmetic on the Intel Itanium architecture|website=decus.de|access-date=December 21, 2020|date=2003}}</ref>

As with the VAX to Alpha port, a binary translator for Alpha to Itanium was made available, allowing user-mode OpenVMS Alpha software to be ported to Itanium in situations where it was not possible to recompile the source code. This translator is known as the ''Alpha Environment Software Translator'' (AEST), and it also supported translating VAX executables which had already been translated with VEST.<ref>{{cite web|url=http://www.decus.de/slides/sy2005/06_04/2g05.pdf|access-date=December 21, 2020|website=decus.de|date=2005|title=OpenVMS Moving Custom Code|author=Thomas Siebold}}</ref>

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 first production release, V8.2, was released in February 2005. V8.2 was also released for Alpha; subsequent V8.x releases of OpenVMS have maintained feature parity between the Alpha and Itanium architectures.<ref>{{cite web|url=http://de.openvms.org/TUD2005/12_Open_VMS_Strategy_Paul_Lacombe.pdf|title=HP OpenVMS Strategy and Futures|author=Paul Lacombe|date=2005|access-date=December 21, 2020|website=de.openvms.org|archive-date=February 7, 2021|archive-url=https://web.archive.org/web/20210207063543/http://de.openvms.org/TUD2005/12_Open_VMS_Strategy_Paul_Lacombe.pdf|url-status=dead}}</ref>

===Port to x86-64===

When VMS Software Inc. (VSI) announced that they had secured the rights to develop the OpenVMS operating system from HP, they also announced their intention to port OpenVMS to the [[x86-64]] architecture.<ref>{{cite press release|url=http://www.businesswire.com/news/home/20140731006118/en/VMS-Software-Named-Exclusive-Developer-Future-Versions|title=VMS Software, Inc. Named Exclusive Developer of Future Versions of OpenVMS Operating System.|date=July 31, 2014|archive-url=https://web.archive.org/web/20140810031139/http://www.businesswire.com/news/home/20140731006118/en/VMS-Software-Named-Exclusive-Developer-Future-Versions#.U-bjA7xxfZt|archive-date=August 10, 2014}}</ref> The porting effort ran concurrently with the establishment of the company, as well as the development of VSI's own Itanium and Alpha releases of OpenVMS V8.4-x.

The x86-64 port is targeted for specific servers from [[Hewlett Packard Enterprise|HPE]] and [[Dell]], as well as certain virtual machine [[hypervisor]]s.<ref name="vms-roadmap-12-2019">{{cite web|url=https://vmssoftware.com/pdfs/VSI_Roadmap_20191209.pdf|title=OpenVMS Rolling Roadmap|date=December 2019|publisher=VSI|archive-url=https://web.archive.org/web/20200610041353/https://vmssoftware.com/pdfs/VSI_Roadmap_20191209.pdf|archive-date=June 10, 2020|url-status=dead|access-date=May 4, 2021}}</ref> Initial support was targeted for [[Kernel-based Virtual Machine|KVM]] and [[VirtualBox]]. Support for [[VMware]] was announced in 2020, and [[Hyper-V]] is being explored as a future target.<ref>{{cite web|url=https://vmssoftware.com/about/v9-qa/|title=VSI V9.0 Q&A|website=VSI|access-date=April 27, 2024}}</ref> In 2021, the x86-64 port was demonstrated running on an [[Intel Atom]]-based [[single-board computer]].<ref>{{cite AV media|url=https://www.youtube.com/watch?v=3H6AJigJnNs |archive-url=https://ghostarchive.org/varchive/youtube/20211211/3H6AJigJnNs| archive-date=December 11, 2021 |url-status=live|title=OpenVMS x64 Atom Project|date=June 1, 2021|access-date=June 2, 2021|author=VSI|website=[[YouTube]]}}{{cbignore}}</ref>

As with the Alpha and Itanium ports, the x86-64 port made some changes to simplify porting and supporting OpenVMS on the new platform including: replacing the proprietary GEM compiler backend used by the VMS compilers with [[LLVM]],<ref>{{cite AV media|url=https://www.youtube.com/watch?v=xTaBkCBYskA |archive-url=https://ghostarchive.org/varchive/youtube/20211211/xTaBkCBYskA| archive-date=December 11, 2021 |url-status=live|title=2017 LLVM Developers' Meeting: J. Reagan "Porting OpenVMS using LLVM"|website=[[YouTube]]|date=October 31, 2017}}{{cbignore}}</ref> changing the boot process so that OpenVMS is booted from a memory disk,<ref>{{cite web|url=http://www.vmssoftware.com/pdfs/State_of_Port_20170105.pdf|title=State of the Port to x86_64 January 2017.|date=January 6, 2017|archive-url=https://web.archive.org/web/20191104221854/http://www.vmssoftware.com/pdfs/State_of_Port_20170105.pdf|archive-date=November 4, 2019|url-status=dead}}</ref> and simulating the four privilege levels of OpenVMS in software since only two of x86-64's privilege levels are usable by OpenVMS.<ref name="swis">{{cite AV media|url=https://www.youtube.com/watch?v=U8kcfvJ1Iec |archive-url=https://ghostarchive.org/varchive/youtube/20211211/U8kcfvJ1Iec| archive-date=December 11, 2021 |url-status=live|title=Re-architecting SWIS for X86-64|date=October 8, 2017|author=Camiel Vanderhoeven|website=[[YouTube]]|access-date=October 21, 2021}}{{cbignore}}</ref>

The first boot was announced on May 14, 2019. This involved booting OpenVMS on VirtualBox, and successfully running the <code>[[Directory (OpenVMS command)|DIRECTORY]]</code> command.<ref>{{cite web|url=https://vmssoftware.com/about/news/2019-05-14-vms-software-inc-announces-first-boot-on-x86-architecture/|title=VMS Software Inc. Announces First Boot on x86 Architecture|date=May 14, 2019|access-date=May 4, 2021|website=VSI}}</ref> In May 2020, the V9.0 Early Adopter's Kit release was made available to a small number of customers. This consisted of the OpenVMS operating system running in a VirtualBox VM with certain limitations; most significantly, few layered products were available, and code can only be compiled for x86-64 using cross compilers which run on Itanium-based OpenVMS systems.<ref name="9.0 Rollout">{{cite web|url=https://vmssoftware.com/docs/may-19-2020-v9.0-rollout-and-beyond.pdf|title=Rollout of V9.0 and Beyond|date=May 19, 2020|access-date=May 4, 2021|website=VSI}}</ref> Following the V9.0 release, VSI released a series of updates on a monthly or bimonthly basis which added additional functionality and hypervisor support. These were designated V9.0-A through V9.0-H.<ref name="state-of-the-port">{{cite web|url=https://vmssoftware.com/updates/state-of-the-port/|archive-url=https://web.archive.org/web/20210418211710/https://vmssoftware.com/about/state-of-the-port/|archive-date=April 18, 2021|url-status=dead|title=State of the Port|access-date=April 16, 2021|website=VSI}}</ref> In June 2021, VSI released the V9.1 Field Test, making it available to VSI's customers and partners.<ref name="vms-9.1">{{cite web|url=https://vmssoftware.com/about/openvmsv9-1/|title=OpenVMS 9.1|date=June 30, 2021|access-date=June 30, 2021|website=VSI|archive-url=https://web.archive.org/web/20210630172618/https://vmssoftware.com/about/openvmsv9-1/|archive-date=June 30, 2021|url-status=dead}}</ref> V9.1 shipped as an [[ISO image]] which can be installed onto a variety of hypervisors, and onto [[ProLiant|HPE ProLiant DL380]] servers starting with the V9.1-A release.<ref name="vsi-9.1-A">{{cite web|url=https://vmssoftware.com/about/news/2021-09-30-openvms-9/|title=VMS Software Releases OpenVMS V9.1-A|date=September 30, 2021|access-date=September 30, 2021|website=VSI}}</ref>

===Influence===
During the 1980s, the MICA operating system for the PRISM architecture was intended to be the eventual successor to VMS. MICA was designed to maintain backwards compatibility with VMS applications while also supporting [[Ultrix]] applications on top of the same kernel.<ref name="mica-business-plan">{{cite web|url=http://www.bitsavers.org/pdf/dec/prism/mica/Mica_Software_Business_Plan_Mar87.pdf|title=MICA Software Business Plan|author1=Catherine Richardson|author2=Terry Morris|author3=Rockie Morgan|author4=Reid Brown|author5=Donna Meikle|date=March 1987|access-date=January 4, 2021|website=Bitsavers}}</ref> MICA was ultimately cancelled along with the rest of the PRISM platform, leading Dave Cutler to leave DEC for Microsoft. At Microsoft, Cutler led the creation of the [[Windows NT]] operating system, which was heavily inspired by the architecture of MICA.<ref>{{cite book |last1=Zachary |first1=G. Pascal |title=Showstopper!: The Breakneck Race to Create Windows NT and the Next Generation at Microsoft |date=2014 |publisher=Open Road Media |isbn=978-1-4804-9484-8 |url=https://books.google.com/books?id=o2IkAwAAQBAJ&q=%22Dave+Cutler%22+march+13&pg=PT9 |access-date=January 4, 2021|language=en}}</ref> As a result, VMS is considered an ancestor of [[Windows NT]], together with [[RSX-11]], [[VAXELN]] and MICA, and many similarities exist between VMS and NT.<ref>{{cite web|url=https://www.itprotoday.com/compute-engines/windows-nt-and-vms-rest-story|title=Windows NT and VMS: The Rest of the Story|author=Mark Russinovich|date=October 30, 1998|access-date=January 4, 2021|website=ITPro Today}}</ref>

A now-defunct project named ''FreeVMS'' attempted to develop an [[open-source software|open-source]] operating system following VMS conventions.<ref>{{cite web|url=https://www.osnews.com/story/8953/freevms-010-released/|title=FreeVMS 0.1.0 Released|author=Eugenia Loli|date=November 23, 2004|website=OSnews|access-date=April 2, 2022}}</ref><ref name="freevms-homepage">{{cite web|url=http://www.freevms.net/|title=FreeVMS official web page|archive-url=https://web.archive.org/web/20180908204358/http://www.freevms.net/|archive-date=September 8, 2018}}</ref> FreeVMS was built on top of the [[L4 microkernel family|L4 microkernel]] and supported the [[x86-64]] architecture. Prior work investigating the implementation of VMS using a microkernel-based architecture had previously been undertaken as a prototyping exercise by DEC employees with assistance from [[Carnegie Mellon University]] using the [[Mach (kernel)|Mach 3.0]] microkernel ported to [[VAXstation#VAXstation 3100 Series|VAXstation 3100]] hardware, adopting a multiserver architectural model.<ref name="wiecek1992">{{ cite journal | url=https://archive.org/details/1992-proceedings-microkernels-seattle/page/187/mode/1up | title=A Model and Prototype of VMS Using the Mach 3.0 Kernel | journal=Proceedings of the USENIX Workshop on Micro-Kernels and Other Kernel Architectures | last1=Wiecek | first1=Cheryl A. | last2=Kaler | first2=Christopher G. | last3=Fiorelli | first3=Stephen | last4=Davenport, Jr. | first4=William C. | last5=Chen | first5=Robert C. | date=April 1992 | access-date=September 20, 2021 | pages=187–203 }}</ref>