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; 46 years ago (1978-08)
Latest stable release	V9.2-2 / January 25, 2024; 16 months ago (2024-01-25)
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 program that manages all the hardware and software on a computer. It's an operating system that lets many users work on it at once. It also handles many tasks at the same time. OpenVMS is known for being very reliable. It can run for a very long time without needing to be restarted. Some systems have even run for 17 years straight!

This operating system is used by big companies. These include banks, hospitals, and phone companies. It helps them run important services.

OpenVMS was first created in 1977 by Digital Equipment Corporation (DEC). It was called VAX/VMS back then. Over the years, it has been updated to work on different types of computers. Since 2014, a company called VMS Software Inc. (VSI) has been developing and supporting it. OpenVMS can link many computers together. This creates a "cluster" that keeps applications and data available even if one part of the system has problems.

History of OpenVMS

How OpenVMS Began

The "VAX/VMS" logo from Digital

In 1975, Digital Equipment Corporation (DEC) started a big project. They wanted to create a new computer system. The computer part was called Star, and the operating system was called Starlet. This project led to the VAX-11/780 computer and the VAX/VMS operating system. The name Starlet is still used in some parts of OpenVMS today.

OpenVMS was mostly written in special computer languages. These were called VAX MACRO and BLISS. One of the main goals was to make it work with an older DEC operating system, RSX-11M. This helped older programs run on the new VAX/VMS system.

"Albert the Cheshire Cat" was a mascot for VAX/VMS.

Over time, different versions of VAX/VMS were made:

• MicroVMS was a smaller version. It was made for computers with less memory and disk space.
• Desktop-VMS was a version for personal workstations. It came on a single CD-ROM. It was easy to set up for people who weren't computer experts.
• An unofficial version called MOS VP was made in the Soviet Union. It supported the Cyrillic script and had parts translated into Russian.

In 1988, DEC started calling VAX/VMS simply VMS. Then, in 1992, they changed the name again to OpenVMS. This showed that it supported open standards like POSIX and Unix. It also removed the "VAX" part because it was starting to work on other computer types.

Moving to Alpha Computers

"Vernon the Shark" was a logo for OpenVMS.

In the 1980s, DEC planned to replace VAX computers. They wanted to use a new type of computer called PRISM. When that plan was canceled, a team decided to make VMS work on a different kind of fast computer. This led to the creation of the Alpha computer.

The team started moving VMS to Alpha computers in 1989. It was a big challenge because VMS was designed specifically for VAX computers. Many parts of VMS were written in a special code called VAX MACRO. To make it work on Alpha, they created new tools. These tools helped translate the old code to work on the new Alpha computers.

The first version of OpenVMS for Alpha computers came out in 1992. It was called OpenVMS AXP V1.0. Later, in 1994, the VAX and Alpha versions of OpenVMS became very similar. They had the same features and version numbers.

At first, OpenVMS on Alpha was still a 32-bit system. This meant it could only use a certain amount of memory. Later, in version 7.0, it was updated to 64-bit. This allowed it to use much more memory. It could even mix 32-bit and 64-bit code.

One cool feature on Alpha was OpenVMS Galaxy. This allowed one powerful computer to act like several smaller OpenVMS systems.

Moving to Intel Itanium Computers

"Swoosh" logo used by HP for OpenVMS.

In 2001, the company Compaq (which later became part of Hewlett-Packard) decided to move OpenVMS to Intel's Itanium computer chips. This was because Compaq stopped developing the Alpha chips. The work to move OpenVMS to Itanium started in late 2001. The first successful start-up happened in January 2003.

This move was done by sharing much of the same code used for OpenVMS Alpha. They added special parts for Itanium where needed. They also changed how the system started up and handled different types of data.

A special tool was made to help old Alpha programs run on Itanium. This was useful if companies couldn't update their old software. The first full version for Itanium, V8.2, was released in February 2005. This version also came out for Alpha, keeping the two systems similar.

Moving to x86-64 Computers

When VMS Software Inc. (VSI) took over OpenVMS development, they announced a new goal. They wanted to make OpenVMS work on common x86-64 computers. These are the types of computers most people use today. This work happened while the company was just starting up.

The x86-64 version is designed to run on specific computers from HPE and Dell. It also works on virtual machines like KVM and VirtualBox. Support for VMware was added later.

Like the previous moves, VSI made changes to OpenVMS. They updated how the system compiles code and how it starts up. The first successful start-up on x86-64 was announced in May 2019. In May 2020, an early version was given to a few customers. VSI has continued to release updates, adding more features and support for different virtual machines and hardware.

How OpenVMS Influenced Other Systems

In the 1980s, DEC planned a new operating system called MICA. It was meant to replace VMS. MICA was designed to work with both VMS and Ultrix (a type of Unix). When MICA was canceled, a key engineer, Dave Cutler, left DEC. He went to Microsoft.

At Microsoft, Dave Cutler led the creation of the Windows NT operating system. Windows NT was greatly inspired by MICA. Because of this, OpenVMS is seen as an ancestor of Windows NT. Many parts of Windows NT are similar to OpenVMS.

There was also a project called FreeVMS. It tried to create an open-source version of VMS. This means anyone could see and change its code.

How OpenVMS Works

The layers of the OpenVMS operating system.

OpenVMS is built in layers, like a cake. At the very bottom is the Executive. This is the most powerful part. Above it are other parts that handle commands and programs. Programs usually ask the Executive for help through "system services." These are like special requests.

OpenVMS uses some special features of the VAX computer design. These include:

• Different access modes (like security levels) for different parts of the system.
• A special way of organizing computer memory.
• Ways to handle interruptions and keep things in sync.

These features are now made to work on Alpha, Itanium, and x86-64 computers. They either use similar features on those computers or pretend to have them.

The Executive and Kernel

The Executive is the powerful code and data that runs the system. It has a core part called the Kernel. The Kernel is the most important part. It manages the computer's memory, how programs run, and how data is saved.

The Kernel holds the main information about the operating system. It handles things like managing files, scheduling tasks, and keeping everything in order.

OpenVMS allows special programs to access these powerful parts. This helps add new features to the operating system.

File System and Data Storage

The main way users and programs interact with files is through something called Record Management Services (RMS). OpenVMS supports different ways of storing files on disks. These are called On-Disk Structures (ODS), like ODS-2 and ODS-5. OpenVMS can also read files from ISO 9660 CD-ROMs and magnetic tapes.

Files-11, the main file system, has a size limit of 2 terabytes. There have been talks about using a newer file system called GFS2 with OpenVMS.

Command Language Interpreter (CLI)

The DIGITAL Command Language (DCL) is the main way you talk to OpenVMS. It's like a special language for giving commands to the computer. You type commands, and DCL makes them happen. It can also run "command procedures," which are like scripts that run many commands at once.

Unlike some other operating systems, DCL runs within the same space as your programs. This means it can easily control and manage them. It has a higher level of privilege to protect itself from accidental changes by other programs.

Key Features of OpenVMS

Clustering Computers Together

VAXstation 4000 model 96 running OpenVMS V6.1.

OpenVMS is famous for its clustering ability. This means you can connect many computers together. They all work as one big system. These connected computers can share things like disk drives and printers. This makes the system very reliable. If one computer breaks down, the others can keep working.

OpenVMS clusters can have up to 96 computers. They can even mix different types of computers. This helps applications keep running even during planned updates or unexpected problems.

Networking and Connections

OpenVMS has a special network system called DECnet. It's built right into the operating system. This allows computers to log in to each other remotely. They can also easily share files and printers over a network. Modern OpenVMS supports both older and newer versions of DECnet.

OpenVMS also supports TCP/IP. This is the common language of the internet. It allows OpenVMS systems to connect to the internet and use services like email and file transfer.

DEC also made software called PATHWORKS. This allowed personal computers to connect to VMS systems. They could use VMS as a file or print server.

Programming Languages and Tools

OpenVMS supports many different programming languages. These include:

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

OpenVMS has a special feature called the Common Language Environment. This means that programs written in different languages can easily work together. For example, a part of a program written in Fortran can be used by another part written in COBOL. This makes it easier for developers to build complex software.

Tools for Developers

DEC provided many tools to help people create software for VMS. These tools were part of a package called DECset. They included:

• A special editor for writing code.
• A system to manage different versions of code.
• Tools to build software projects.
• Tools to check code for errors and improve its performance.

OpenVMS also has powerful debuggers. These help programmers find and fix problems in their code. In 2019, VSI released a new tool. It allows developers to create and test VMS programs using Visual Studio Code on other computers.

Managing Databases

DEC also created many optional database products for VMS. Databases are like organized collections of information. Some of these products included:

• Rdb: A system for organizing data in tables.
• DBMS: Another database system.
• Digital Standard MUMPS (DSM): A language and database combined.
• Common Data Dictionary (CDD): A central place to store information about how data is organized.

Many of these database products were later sold to other companies like Oracle and InterSystems. They are still used and developed today. Other companies also offer their databases for OpenVMS.

User Interfaces: How You Interact with OpenVMS

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

OpenVMS was first designed to be used with text-based terminals. These were like screens where you typed commands. Later, with the VAXstation computers, OpenVMS started to support graphical user interfaces (GUIs). These are interfaces with windows, icons, and menus, like what you see on modern computers.

Text-Based Interfaces

The DIGITAL Command Language (DCL) is the main way to use OpenVMS by typing commands. There are also tools to create text-based applications. These applications use text to create menus and forms on the screen.

Graphical Interfaces (DECwindows)

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

Over the years, OpenVMS has had different graphical interfaces:

• The first one was VMS Workstation Software (VWS) in 1984.
• In 1989, DEC replaced VWS with DECwindows. This was based on the X11 system, which is common for graphical interfaces on Unix-like systems.
• Later, DECwindows used the Motif toolkit. This made the interface look more modern.
• In 1996, a "New Desktop" interface was added. It was based on the Common Desktop Environment (CDE). This is the interface you see in the infobox image.

Modern versions of DECwindows use the X.Org Server, which is a widely used system for displaying graphics.

Security Features

OpenVMS has many security features. It uses special IDs and lists to control who can access what. It also has ways to detect if someone is trying to break in. It can keep detailed records of security events. Some versions of OpenVMS have been tested and approved for high levels of security.

Past Weak Spots

In the past, some early versions of VMS had default passwords for important accounts. Sometimes, system managers didn't change these passwords. This allowed some computer worms to get into systems. A famous book, The Cuckoo's Egg, described how this happened. After this, OpenVMS made it mandatory to set passwords during setup.

In 2017, a weak spot was found in older versions of VMS. It allowed someone with access to the command line to gain more control over the system. This was fixed in later versions.

Working with Unix Programs

OpenVMS has ways to run programs that were made for Unix and POSIX systems. This means it can be compatible with many other software tools. DEC provided tools like DEC/Shell and POSIX for OpenVMS. Later, an open-source project called GNV (GNU's not VMS) was included. GNV allows OpenVMS to use many common Unix tools, including the Bash shell.

OpenVMS for Hobbyists

Since 1997, OpenVMS has been available for free to hobbyists. These are people who use it for fun or learning, not for business. This program was called the OpenVMS Hobbyist Program. Other companies also made their OpenVMS software available for hobbyists.

In 2020, HPE ended the old Hobbyist Program. But VSI started a new one called the Community License Program (CLP). This program provides licenses for VSI's newer OpenVMS versions on Alpha, Integrity, and x86-64 systems.

OpenVMS Release History

See also

In Spanish: OpenVMS para niños

• Comparison of operating systems