OpenVMS facts for kids

Quick facts for kids
OpenVMS

OpenVMS V7.3-1 running the CDE-based DECwindows "New Desktop" GUI
Company / developer	VMS Software Inc (VSI) (previously Digital Equipment Corporation, Compaq, Hewlett-Packard)
Programmed in	Primarily C, BLISS, VAX MACRO, DCL. Other languages also used.
Working state	Current
Source model	Closed-source with open-source components. Formerly source available
Initial release	Announced: October 25, 1977; 47 years ago (1977-10-25) V1.0 / August 1978; 47 years ago (1978-08)
Latest stable release	V9.2-3 / November 20, 2024; 8 months ago (2024-11-20)
Marketing target	Servers (historically Minicomputers, Workstations)
Available language(s)	English, Japanese. Historical support for Chinese (both Traditional and Simplified characters), Korean, Thai.
Update method	Concurrent upgrades, rolling upgrades
Package manager	PCSI and VMSINSTAL
Supported platforms	VAX, Alpha, Itanium, x86-64
Kernel type	Monolithic kernel with loadable modules
Influenced	VAXELN, MICA, Windows NT
Influenced by	RSX-11M
Default user interface	DCL CLI and DECwindows GUI
License	Proprietary

OpenVMS, often called VMS, is a special computer operating system. It lets many users work at once and handles many tasks at the same time. It also uses "virtual memory," which helps computers use their memory efficiently.

OpenVMS is designed for different types of computer work. This includes sharing computer time among many users and running large jobs in batches. It also handles many quick transactions, like those in banking.

Many important organizations use OpenVMS. These include banks, hospitals, and phone companies. It is also used by internet service providers and factories. In the 1990s and 2000s, about half a million VMS systems were in use worldwide.

Digital Equipment Corporation (DEC) first announced VMS in 1977. It was called VAX/VMS then. It came out with the VAX-11/780 minicomputer. Over time, OpenVMS was updated to work on newer computers. These include DEC Alpha systems and Itanium-based servers. It also runs on some x86-64 computers and hypervisors (software that creates virtual machines).

Since 2014, VMS Software Inc. (VSI) has developed and supported OpenVMS. OpenVMS is known for its "clustering" feature. This means it can link many computers together. If one computer has a problem, the others can keep working. This helps applications and data stay available all the time. Some VMS clusters have run for 17 years without stopping!

History of OpenVMS

How OpenVMS Started

The "VAX/VMS" logo used by Digital

In 1975, DEC started a project to create a new computer system. The computer part was called Star, and the operating system was called Starlet. Roger Gourd led the VMS project. Software engineers Dave Cutler, Dick Hustvedt, and Peter Lipman were also key leaders.

They wanted the new operating system to do many things. It needed to handle real-time tasks, time-sharing, and transaction processing. The Star and Starlet projects led to the VAX-11/780 computer and the VAX/VMS operating system. Some parts of VMS still use the "Starlet" name. VMS was mostly written in VAX MACRO and BLISS programming languages.

One main goal for VMS was to work with older DEC software. This was for the RSX-11M operating system. Early VAX/VMS versions had a special part called "RSX Application Migration Executive." This let old RSX-11M programs run on VMS without changes.

"Albert the Cheshire Cat" mascot for VAX/VMS

By the early 1980s, VAX/VMS was very popular. Many companies wanted it. Different versions of VAX/VMS were made for various needs:

• MicroVMS was for smaller VAX computers. It let users install only the parts of VMS they needed.
• Desktop-VMS was a short-lived version for VAXstation systems. It came on a single CD-ROM. It included VMS, DECwindows (a graphical interface), and networking tools. It was easy for non-technical users to set up.

In 1988, DEC started calling VAX/VMS simply VMS. In 1992, it was renamed OpenVMS. This showed its support for "open systems" standards. It also removed the "VAX" name because it was moving to new computer designs.

Moving to Alpha Computers

"Vernon the Shark" logo for OpenVMS

In the 1980s, DEC planned to replace VAX with a new system called PRISM. But this project was canceled in 1988. So, a new team started to make VMS work on a different type of computer. This led to the creation of the Alpha computer design.

The project to move VMS to Alpha started in 1989. The first version of OpenVMS for Alpha computers came out in 1992. It was called OpenVMS AXP V1.0.

Moving VMS to Alpha was hard because VMS was built specifically for VAX computers. Many parts of VMS were written in a special VAX assembly language. To fix this, DEC created a new compiler. This compiler could turn the old VAX code into code for Alpha computers.

At first, OpenVMS on Alpha was still a 32-bit system. This helped old software keep working. Later, in 1996, 64-bit addressing was added. This allowed OpenVMS to use much more memory.

One cool feature for Alpha was OpenVMS Galaxy. This allowed a single powerful server to run multiple copies of OpenVMS at the same time. It could also share memory between these copies.

Moving to Intel Itanium Computers

"Swoosh" logo used by HP for OpenVMS

In 2001, Compaq (which later became part of Hewlett-Packard) announced a plan. They would move OpenVMS to Intel's Itanium computer design. This was because Compaq decided to stop developing the Alpha design.

The work to move VMS to Itanium began in late 2001. The first successful start-up of VMS on an Itanium computer happened in 2003. This involved starting a basic system and running a simple command.

The Itanium version of OpenVMS works on specific HPE Integrity Servers. These versions were often called OpenVMS I64. The move to Itanium required many changes. For example, VMS had to use new ways to start up and new file formats.

Two test versions were released in 2003. The first full version, V8.2, came out in 2005. This version was also released for Alpha computers. Later V8.x versions kept the same features for both Alpha and Itanium.

Moving to x86-64 Computers

When VMS Software Inc. (VSI) took over OpenVMS development, they announced a new goal. They wanted to move OpenVMS to the x86-64 computer design. This work happened while VSI was also releasing updates for Itanium and Alpha.

The x86-64 version works on specific servers from HPE and Dell. It also runs on virtual machine software like KVM and VirtualBox. Support for VMware was added in 2020.

The first successful start-up on x86-64 was announced in 2019. This involved running OpenVMS on VirtualBox and using a basic command. In 2020, VSI released an early version for some customers. This version had some limits, like fewer extra programs.

VSI continued to release updates for x86-64 every month or two. These updates added more features and support for more virtual machine software. In 2021, VSI released a test version, V9.1. It could be installed on various virtual machines and on HPE ProLiant DL380 servers.

How OpenVMS Influenced Other Systems

In the 1980s, a system called MICA was planned to replace VMS. MICA was designed to work with both VMS and Unix programs. But the MICA project was canceled.

After this, Dave Cutler, a key VMS engineer, went to Microsoft. There, he led the creation of the Windows NT operating system. Windows NT was greatly inspired by MICA's design. Because of this, OpenVMS is seen as an ancestor of Windows NT. Many similarities exist between VMS and NT.

How OpenVMS Works

The architecture of the OpenVMS operating system, showing its layers

OpenVMS has a layered design. It has a powerful "Executive" part, a "Command Language Interpreter," and other tools. Regular programs usually ask the Executive for help using "system services."

OpenVMS uses special features of the VAX computer design. These include different "access modes" (like security levels) for programs. Each mode has its own memory area. It also uses "interrupt priority levels" to manage tasks. These VAX features are copied or simulated on Alpha, Itanium, and x86-64 computers.

Executive and Kernel

The OpenVMS Executive contains the main code and data. It lives in a special part of the computer's memory. The Executive has a "Kernel" part, which is the most powerful. Other parts of the Executive are less powerful but still important.

The Kernel holds the most important data for the operating system. It also has routines that work with this data. The Kernel handles input/output (I/O), manages processes and time, and controls memory. It also manages logical names and helps programs work together.

OpenVMS lets programs with special permissions access the Executive and Kernel. This allows advanced tools and extensions to work closely with the operating system.

File System

Users and applications usually interact with files using the Record Management Services (RMS). Programs can also talk directly to the file system. OpenVMS supports file systems called Files-11 On-Disk Structures (ODS). The most common are ODS-2 and ODS-5. VMS can also read files from ISO 9660 CD-ROMs and magnetic tapes.

Files-11 has a limit of 2 terabytes (TB) for storage volumes. There have been talks about adding support for the GFS2 file system to OpenVMS.

Command Language Interpreter

The DIGITAL Command Language (DCL) is the main way to give commands to OpenVMS. It lets users type commands and run "command procedures" (like scripts). Other command interpreters are also available.

Unlike some other operating systems, DCL is part of the computer's process. It loads programs into the same process. When a program finishes, DCL takes back control. This design helps DCL manage programs and keep the system stable.

Key Features

VAXstation 4000 model 96 running OpenVMS V6.1, DECwindows Motif and the NCSA Mosaic browser

Clustering

OpenVMS supports clustering, which means connecting many computers together. These computers (called nodes) can work independently or share devices like disk drives and printers. They act like one big system.

OpenVMS clusters can have up to 96 nodes. They can also mix different types of computers. This feature helps applications keep running even if some hardware or software needs maintenance. It also helps if part of the cluster breaks down.

Networking

The DECnet protocol is built into VMS. It allows users to log in to remote computers. It also provides easy access to files, printers, and other resources over a network. Modern VMS versions support both old and new DECnet protocols.

OpenVMS also supports TCP/IP, which is the main internet protocol. This support comes from an extra software package. It includes tools for common internet services like SSH, DHCP, FTP, and SMTP.

DEC also sold software called PATHWORKS. This allowed personal computers (like those running MS-DOS or Microsoft Windows) to connect to VMS systems. They could use VMS as a file or print server. Later, this was replaced with a VMS version of Samba.

Programming

DEC and its later companies offered many programming languages for VMS. Some of these include:

• C
• Fortran
• Pascal
• COBOL
• BASIC
• C++
• Java
• Lua

OpenVMS has a "Common Language Environment." This is a set of rules for how programs talk to each other. It means that code written in one language (like Fortran) can easily work with code written in another (like COBOL). This makes it easy to mix different languages in one project.

Development Tools

The "Grey Wall" of VAX/VMS documentation

DEC provided a set of software development tools called DECset. These tools included:

• Language-Sensitive Editor (LSE) for writing code.
• Code Management System (CMS) for tracking changes to code.
• Module Management System (MMS) for building software.
• Source Code Analyzer (SCA) for checking code quality.
• Performance and Coverage Analyzer (PCA) for finding slow parts of code.
• Digital Test Manager (DTM) for managing software tests.

OpenVMS also includes text editors like EDT and EVE. The OpenVMS Debugger helps programmers find and fix errors in their code. It works with many languages.

In 2019, VSI released a tool for VMS based on Visual Studio Code. This lets developers write and debug VMS programs from other computers.

Database Management

DEC created many database products for VMS. These included:

• Rdb – a database system that stores data in tables.
• DBMS – another database system that uses a network model.
• Digital Standard MUMPS (DSM) – a programming language with a built-in database.
• Common Data Dictionary (CDD) – a central place to store information about databases.
• DATATRIEVE – a tool for asking questions and making reports from databases.

In 1994, DEC sold Rdb, DBMS, and CDD to Oracle. They are still being developed today. DSM was sold to InterSystems. Other companies also make databases for OpenVMS, like MariaDB.

User Interfaces

OpenVMS Alpha V8.4-2L1, showing the DCL CLI

VMS was first used with text-based terminals. These were like old-fashioned computer screens that only showed text. Since 1984, VMS has also supported graphical user interfaces (GUIs). These are like the windows and icons you see on modern computers.

Text-based Interfaces

The DIGITAL Command Language (DCL) is the main text-based way to control OpenVMS. DEC also provided tools to create text-based applications. These included Form Management System (FMS) and Terminal Data Management System (TDMS).

Graphical Interfaces

VWS 4.5 running on top of VAX/VMS V5.5-2

DECwindows XUI window manager running on top of VAX/VMS V5.5-2

Over the years, VMS has used different graphical interfaces:

• The first GUI for VMS was called VMS Workstation Software (VWS). It came out in 1984.
• In 1989, DEC replaced VWS with DECwindows. This was based on X11, a common system for graphical interfaces. Early DECwindows used a special toolkit called X User Interface (XUI).
• In 1991, DEC switched to the Motif toolkit for DECwindows Motif. This became the default interface.
• In 1996, OpenVMS V7.1 introduced the New Desktop interface. This was based on the Common Desktop Environment (CDE). It looked more like modern desktop environments.

OpenVMS on Alpha workstations also supported OpenGL for graphics. Modern DECwindows versions use X.Org Server.

Security Features

OpenVMS has many security features. These include special identifiers for users and resources. It also uses ACLs to control who can access what. OpenVMS can detect intrusions and keep detailed security records.

Security Issues

• Early versions of VMS had some default passwords for important accounts. System managers sometimes did not change these. Some computer worms used these default passwords to get into systems. This problem was also described in the book The Cuckoo's Egg. In 1988, VMS removed these default passwords.
• In 2017, a very old security flaw was found in VMS on VAX and Alpha systems. This flaw allowed an attacker to gain higher permissions on the system. It used a problem in how DCL commands were processed.

POSIX Compatibility

OpenVMS has ways to run programs made for Unix and POSIX systems. The first was DEC/Shell, which included parts of the Bourne shell and other Unix tools. Later, POSIX for OpenVMS was released.

This was replaced by an open-source project called GNV (GNU's not VMS). GNV was included with OpenVMS starting in 2002. It includes the Bash shell and other GNU tools.

Hobbyist Programs

In 1997, OpenVMS was made free for hobbyists and non-commercial use. This was part of the OpenVMS Hobbyist Program. Other companies also made their OpenVMS software available for free to hobbyists. Before the x86-64 version, many hobbyists used emulators like SIMH to run OpenVMS.

In 2020, HPE ended the original Hobbyist Program. VSI then started the Community License Program (CLP) as a replacement. The CLP launched in July 2020. It provides licenses for VSI OpenVMS versions on Alpha, Integrity, and x86-64 systems.

Release History

See also

In Spanish: OpenVMS para niños

• Comparison of operating systems
• Terry Shannon