VMS (OpenVMS)

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Stands for: Virtual Memory System: DEC's VAX/VMS of 1977, OpenVMS since 1992, now developed by VMS Software Inc. on x86-64

Virtual Memory System: the operating system DEC announced with the VAX-11/780 in 1977 as VAX/VMS, renamed OpenVMS in 1992, ported to Alpha, Itanium and now x86-64, and developed since 2014 by VMS Software Inc.

VMS is the other great operating system lineage of the minicomputer era, and the one that did not die with its maker. Digital Equipment Corporation announced VAX/VMS, Virtual Address eXtension and Virtual Memory System, alongside the VAX-11/780 in 1977, with Dave Cutler, Dick Hustvedt and Peter Lipman as technical project leaders of the Star and Starlet projects that produced the machine and the system. It is a multi-user, multiprocessing, virtual memory operating system with high availability through clustering, the ability to distribute one system over many physical machines, and its customers are banks and financial service providers, hospitals, telecommunications operators, network information services and manufacturers. In July 1992 DEC renamed it OpenVMS to signal support for open-systems standards such as POSIX and Unix compatibility and to drop the VAX from the name as the Alpha port arrived; the name was first used with OpenVMS AXP V1.0 in November 1992. It has since been ported to the Itanium-based HPE Integrity servers and to x86-64, and since 2014 it is developed and supported by VMS Software Inc., whose x86-64 early adopter kit shipped in May 2020.

Origins. OpenVMS, often referred to simply as VMS, was first announced by Digital Equipment Corporation as VAX/VMS alongside the VAX-11/780 minicomputer in 1977. The Star project produced the VAX architecture and the Starlet project its operating system, with software engineers Dave Cutler, Dick Hustvedt and Peter Lipman as technical project leaders. The system is multi-user, multiprocessing and virtual-memory based, and from early on offered clustering: the ability to distribute the system over multiple physical machines, so that a cluster survives the loss of a member. That is the property its remaining customers pay for.

The renaming and the ports. During the 1980s DEC planned to replace the VAX and VMS with the PRISM architecture and the MICA operating system; that plan ended, and led to the Alpha architecture instead. In July 1992 DEC renamed VAX/VMS to OpenVMS as an indication of its support of open systems industry standards such as POSIX and Unix compatibility, and to drop the VAX connection since a migration to a different architecture was under way. The OpenVMS name was first used with the OpenVMS AXP V1.0 release in November 1992, and DEC began using OpenVMS VAX with V6.0 in June 1993. The system was subsequently ported to the Itanium-based HPE Integrity servers and, most recently, to x86-64. The VAX architecture mechanisms the system depends on, its four privilege levels among them, are implemented on Alpha, Itanium and x86-64 either by mapping to the hardware or by emulation, via PALcode on Alpha and in software on the other two.

VMS Software Inc. and x86-64. Since 2014 OpenVMS has been developed and supported by VMS Software Inc., VSI, which on securing the rights from HP announced its intention to port the system to x86-64. The port targets specific HPE and Dell servers and virtual machine hypervisors; VMware support was announced in 2020 and Hyper-V explored. The port replaced the proprietary GEM compiler back end with LLVM, changed the boot process to start from a memory disk, and simulates the four privilege levels in software. In May 2020 the V9.0 Early Adopter's Kit went to a small number of customers as a VirtualBox image with cross compilers running on Itanium; in 2021 the port was demonstrated on an Intel Atom single-board computer. HPE ended its OpenVMS Hobbyist Program in March 2020, and VSI launched a Community License Program in July 2020 covering Alpha, Integrity and x86-64.

Why a network glossary keeps it. Two reasons. The people: Cutler went on to Microsoft, where Windows NT was, in the encyclopaedia's phrase on the DEC record, made possible by former Digital engineers, which is why NT's internals read like VMS to anyone who knew both. And the installations: OpenVMS clusters still run billing, trading, hospital and manufacturing systems that cannot be stopped, and the network engineer who inherits one needs to know that DECnet may still be on the wire beside TCP/IP. The Digital Equipment Corporation record on the industry timeline carries the company from the Maynard mill to Compaq.

Also known as: vms, vax/vms, vax vms, openvms, vsi openvms, dec vms

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