OpenVMS (Open Virtual Memory System) is a multi-user, multiprocessing virtual memory-based operating system designed for use in time-sharing, batch processing, and transaction processing. It was originally developed by Digital Equipment Corporation (DEC) and has a rich history that spans several decades. This section will cover the key milestones in the development and evolution of OpenVMS.

• 1977: DEC introduces the VAX (Virtual Address eXtension) computer architecture, which is designed to support a new operating system.
• 1978: The first version of VMS (Virtual Memory System) is released for the VAX-11/780. VMS is designed to take full advantage of the VAX architecture, offering advanced features like virtual memory, process scheduling, and file management.

• 1980: VMS gains popularity in various industries due to its robustness, reliability, and scalability.
• 1984: VMS V4.0 is released, introducing significant enhancements such as clustering (VAXcluster), which allows multiple VAX systems to work together as a single system.
• 1988: VMS V5.0 is released, further improving clustering capabilities and adding support for new hardware.

• 1991: DEC rebrands VMS as OpenVMS to emphasize its open systems capabilities and support for industry standards.
• 1992: OpenVMS V6.0 is released, introducing support for the Alpha AXP architecture, a 64-bit RISC architecture developed by DEC.
• 1998: Compaq acquires DEC, continuing the development and support of OpenVMS.

• 2001: OpenVMS V7.3 is released, offering enhanced performance, scalability, and support for modern hardware.
• 2002: Hewlett-Packard (HP) acquires Compaq, taking over the development and support of OpenVMS.
• 2004: OpenVMS V8.2 is released, introducing support for the Itanium architecture, a 64-bit architecture developed by Intel.

• 2013: HP announces the formation of VMS Software Inc. (VSI), a company dedicated to the development and support of OpenVMS.
• 2015: VSI releases OpenVMS V8.4-1H1, the first version developed independently of HP.
• 2020: VSI announces plans to port OpenVMS to the x86-64 architecture, ensuring the operating system's continued relevance and compatibility with modern hardware.

• OpenVMS introduced clustering technology early in its development, allowing multiple systems to work together seamlessly. This feature has evolved to support larger and more complex clusters, providing high availability and disaster recovery capabilities.

• Over the years, OpenVMS has incorporated numerous security features, including advanced user authentication, access control, auditing, and encryption. These features have been continuously updated to meet modern security standards.

• OpenVMS has consistently improved its performance and scalability, supporting larger memory configurations, more processors, and higher I/O throughput. These enhancements ensure that OpenVMS can handle the demands of modern enterprise applications.

• OpenVMS has been ported to multiple hardware architectures, including VAX, Alpha, Itanium, and soon x86-64. This flexibility allows organizations to run OpenVMS on a wide range of hardware platforms.

The history and evolution of OpenVMS demonstrate its resilience and adaptability in the ever-changing landscape of computing. From its origins as VMS on the VAX architecture to its current development by VSI and upcoming support for x86-64, OpenVMS has consistently provided robust, reliable, and scalable solutions for enterprise computing. Understanding this history provides valuable context for the features and capabilities of OpenVMS, setting the stage for deeper exploration in subsequent modules.