HP OpenVMS IO User's Reference Manual

This document is the HP OpenVMS I/O User's Reference Manual, Version 8.4, primarily aimed at system programmers who need to directly leverage I/O drivers.

The manual provides extensive information on using the Queue I/O (QIO) system service to perform I/O operations across various device types. A significant feature highlighted is the support for 64-bit virtual memory addressing for I/O operations since OpenVMS Version 8.4.

Key areas covered include:

• The ACP-QIO Interface for file system operations, detailing file information blocks, subfunctions (e.g., directory lookup, access, extend, truncate, read/write attributes), and I/O status blocks.

• Specific device drivers for:

  • Storage: Disk, Magnetic Tape, Shadow-Set Virtual Unit, and the OpenVMS Generic SCSI Class Driver.
  • Communication & Interaction: Mailbox, Terminal, Pseudoterminal, and Local Area Network (LAN) Device Drivers. Each driver section outlines its features, device information, function codes, modifiers, error handling, and programming examples.

• Optional features for improving I/O performance, specifically Fast I/O and Fast Path, designed to optimize I/O requests for high-volume scenarios and enhance symmetric multiprocessing (SMP) scaling.

Appendices offer reference material such as QIO function codes, SCSI class driver diagnostic functions, DEC Multinational character sets, pseudoterminal control connection routines, and guidance on programming USB generic drivers.