VAX/VMS Operating System, Version 1.6

VAX/VMS is a general-purpose operating system for the VAX-11/780 series, providing a reliable, high-performance environment for multi-user timesharing, batch, and real-time applications. Key features include virtual memory management, event-driven priority scheduling, and robust data protection for shared memory, files, and interprocess communication based on ownership and application groups. It offers user privilege and resource allocation control, an extendable command language, and multijob batch processing.

The system is optimized for real-time applications, minimizing overhead through hardware context-switching and interrupt mechanisms, and allowing control over virtual memory paging and execution priority. VAX/VMS schedules CPU time and memory residency on a preemptive priority basis, ensuring real-time processes are not delayed by lower-priority tasks. It leverages the VAX-11/780's memory management for dynamic allocation, swapping, paging, and robust protection, both between and within processes, utilizing four processor access modes.

System reliability is ensured through automatic machine and software consistency checks, graceful shutdowns for power failures, and automatic restarts. It supports on-line disk file backups, selective restoration, user-mode diagnostics, and on-line error logging.

For development, VAX/VMS offers tools for both VAX-11 native and PDP-11 compatibility mode programs, including an interactive/batch editor, a symbolic debugger, and a file differences utility. The command language, available via MCR or DCL interpreters, is intuitive and consistent across interactive and batch processing, supporting program development, resource allocation, environmental control, file maintenance, and operational control.

Its record and file management system provides device-independent access to various media, supporting sequential, relative, and multikey indexed file organizations. The disk structure supports volume sets, named directories, and flexible file sharing with automatic or explicit record locking. It's compatible with RSX/IAS file structures and supports multivolume magnetic tape files. A file sort utility and a Common Run-Time Procedure Library are also included.

Programmed system services enable control over processes (creation, communication, synchronization), real-time response (memory locking, priority adjustment), and scheduling. The RSX-11M Application Migration Executive (AME) facilitates migrating and developing RSX-11M applications on VAX/VMS.

The system features automatic installation and bootstrap configuration, with operator override options. A User Environment Test Package (UETP) verifies system integrity post-installation. VAX/VMS adheres to various ANSI, FIPS PUB, and ISO standards, and has specific minimum hardware requirements for VAX-11/780 systems, with support for various optional peripherals and communication devices. Licensing options include single-use licenses, binaries, documentation, listings, and source code availability with specific limitations.