[12][13][14] It was first announced by Digital Equipment Corporation (DEC) as VAX/VMS (Virtual Address eXtension/Virtual Memory System[15]) alongside the VAX-11/780 minicomputer in 1977.

[16][17][18] OpenVMS has subsequently been ported to run on DEC Alpha systems, the Itanium-based HPE Integrity Servers,[19] and select x86-64 hardware and hypervisors.

Software engineers Dave Cutler, Dick Hustvedt, and Peter Lipman acted as technical project leaders.

[31] A number of distributions of VAX/VMS were created: With the V5.0 release in April 1988, DEC began to refer to VAX/VMS as simply VMS in its documentation.

[46] In July 1992,[47] DEC renamed VAX/VMS to OpenVMS as an indication of its support of open systems industry standards such as POSIX and Unix compatibility,[48] and to drop the VAX connection since a migration to a different architecture was underway.

[52] 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.

[56] Furthermore, a significant amount of the VMS kernel, layered products, and customer-developed applications were implemented in VAX MACRO assembly code.

These releases were intended for HP organizations and third-party vendors involved with porting software packages to OpenVMS I64.

[74] 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.

[82] V9.1 shipped as an ISO image which can be installed onto a variety of hypervisors, and onto HPE ProLiant DL380 servers starting with the V9.1-A release.

[84] 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.

[86] A now-defunct project named FreeVMS attempted to develop an open-source operating system following VMS conventions.

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 3.0 microkernel ported to VAXstation 3100 hardware, adopting a multiserver architectural model.

[69] The OpenVMS Executive comprises the privileged code and data structures which reside in the system space.

[90][91] In addition, other functionality such as logical name management, synchronization and system service dispatch are implemented inside the Kernel.

OpenVMS allows user-mode code with suitable privileges to switch to executive or kernel mode using the $CMEXEC and $CMKRNL system services, respectively.

[90][102] OpenVMS supports clustering (first called VAXcluster and later VMScluster), where multiple computers run their own instance of the operating system.

[108] Support for TCP/IP is provided by the optional TCP/IP Services for OpenVMS layered product (originally known as the VMS/ULTRIX Connection, then as the ULTRIX Communications Extensions or UCX).

[109][110] TCP/IP Services is based on a port of the BSD network stack to OpenVMS,[111] along with support for common protocols such as SSH, DHCP, FTP and SMTP.

It allows breakpoints, watchpoints and interactive runtime program debugging using either a command line or graphical user interface.

[124] In 2019, VSI released an officially supported Integrated Development Environment for VMS based on Visual Studio Code.

[75] This allows VMS applications to be developed and debugged remotely from a Microsoft Windows, macOS or Linux workstation.

[125] DEC created a number of optional database products for VMS, some of which were marketed as the VAX Information Architecture family.

[126] These products included: In 1994, DEC sold Rdb, DBMS and CDD to Oracle, where they remain under active development.

Since the introduction of the VAXstation line in 1984, VMS has optionally supported graphical user interfaces for use with workstations or X terminals such as the VT1000 series.

[137][29][9] Other official CLIs available for VMS include the RSX-11 Monitor Console Routine (MCR) (VAX only), and various Unix shells.

[138][139][140] A lower level interface named Screen Management Services (SMG$), comparable to Unix curses, also exists.

[169] Prior to the x86-64 port, the age and cost of hardware capable of running OpenVMS made emulators such as SIMH a common choice for hobbyist installations.

[172] The CLP was launched in July 2020, and provides licenses for VSI OpenVMS releases on Alpha, Integrity and x86-64 systems.