Editing VAX (section)

== Operating systems ==
[[File:VAX VMS logo.svg|thumb|right|Stylized "VAX/VMS" used by Digital]]

The native VAX [[operating system]] is Digital's VAX/VMS (renamed to [[OpenVMS]] in 1991 or early 1992 when it was ported to [[DEC Alpha|Alpha]], modified to comply with [[POSIX]] standards, and ''branded'' as compliant with [[XPG4]] by the [[X/Open]] consortium).<ref name="vaxvmsat20">{{Cite web |editor1-last=Rainville |editor1-first=Jim |editor2-last=Howard |editor2-first=Karen |year=1997 |url=http://h41379.www4.hpe.com/openvms/20th/ |title=VAX/VMS at 20 |publisher=Digital Equipment Corporation |access-date=July 20, 2018 |archive-url=https://web.archive.org/web/20180720225439/http://h41379.www4.hpe.com/openvms/20th/ |archive-date=July 20, 2018 |url-status=dead}}</ref> The VAX architecture and VMS operating system were "[[Concurrent Engineering#Concurrent engineering workflow|engineered concurrently]]" to take maximum advantage of each other, as was the initial implementation of the [[VMScluster|VAXcluster]] facility.

During the 1980s, a [[hypervisor]] for the VAX architecture named ''VMM'' (Virtual Machine Monitor), also known as the ''VAX Security Kernel'', was developed at Digital with the aim of allowing multiple isolated instances of VMS and ULTRIX to be run on the same hardware.<ref>{{cite conference|url=https://www.scs.stanford.edu/nyu/04fa/sched/readings/vmm.pdf|title=A VMM security kernel for the VAX architecture|author1=Paul A. Karger|author2=Mary Ellen Zurko|author3=Douglas W. Benin|author4=Andrew H. Mason|author5=Clifford E. Kahnh|date=May 7–9, 1990|conference=Proceedings. 1990 IEEE Computer Society Symposium on Research in Security and Privacy|access-date=2021-01-31|publisher=IEEE|doi=10.1109/RISP.1990.63834}}</ref> VMM was intended to achieve [[Trusted Computer System Evaluation Criteria|TCSEC]] A1 compliance. By the late 1980s, it was operational on [[VAX 8000]] series hardware, but was abandoned before release to customers.

Other VAX operating systems have included various releases of [[Berkeley Software Distribution]] (BSD) [[UNIX]] up to [[4.3BSD]], [[Ultrix]]-32, [[VAXELN]], and [[Xinu]]. More recently, [[NetBSD]]<ref>{{cite web|url=http://wiki.netbsd.org/ports/vax/|title=NetBSD/vax}}</ref> and [[OpenBSD]]<ref>{{cite web|url=http://www.openbsd.org/vax.html|title=OpenBSD/vax}}</ref> have supported various VAX models and some work has been done on porting [[Linux]] to the VAX architecture.<ref>{{cite web|url=http://vax-linux.org|title=Porting Linux to the VAX}}</ref> OpenBSD discontinued support for the architecture in September 2016.<ref name="obsd60releasenotes">{{Cite web |url=https://www.openbsd.org/60.html |title=OpenBSD 6.0 |year=2016 |access-date=June 20, 2017}}</ref>