VAX/VMS Real-Time User’s Guide

This "VAX/VMS Real-Time User's Guide" (Order No. AA-H784A-TE), published in March 1980, is designed for programmers developing real-time applications on VAX/VMS V02 systems.

The manual discusses VAX/VMS features crucial for high-throughput and fast-response applications, providing programming examples to illustrate complex functionalities. Key areas covered include:

• Real-Time Fundamentals: Introduces the specific needs of real-time applications (high throughput, fast response) and how VAX/VMS features, system tools, real-time devices, user privileges, process quotas, and process priority management address these needs.
• Program Execution Environment Control: Details how to manage the execution environment by creating subprocesses and detached processes, and controlling physical memory allocation through mechanisms like adjusting working set limits, locking pages in memory, and setting process swap modes.
• Inter-Process Communication and Sharing: Explores various methods for processes to communicate, synchronize, and share data/code, such as common event flags, mailboxes, Asynchronous System Trap (AST) service routines, and the use of global sections and shareable images.
• I/O Operations: Provides a comprehensive overview of the VAX/VMS I/O system, with a strong focus on interrupt-generated I/O. It explains how to map I/O space, connect to device interrupt vectors, and implement user-supplied interrupt and AST service routines for direct device control.
• Shared Memory Utilization: Explains the use of multiport memory (MA780) for shared event flags, mailboxes, and global sections to facilitate communication and data sharing among processes running on different processors.
• Privileged Shareable Images: Describes how to create and use privileged shareable images, allowing non-privileged users to invoke privileged functions as custom system services.
• Program Examples and Optimization: Features complete program examples, including a data acquisition and manipulation system (LABIO) and an airline reservation system, to demonstrate real-time concepts. Appendices also offer guidance on resource locking mechanisms and real-time optimization techniques.

The document serves as a guide for real-time programmers to leverage VAX/VMS capabilities for efficient and responsive application design.