OpenVMS Wide Area Network I/O User's Reference Manual

This manual is a comprehensive reference for system programmers looking to interface directly with various communications I/O device drivers in an OpenVMS VAX operating system environment, rather than through OpenVMS Record Management Services. It assumes familiarity with VAX MACRO or high-level assembly language.

The document details five distinct interface drivers:

• DMC11/DMR11 Interface Driver: Describes a synchronous Direct Memory Access (DMA) communications line interface that uses the Digital Data Communications Message Protocol (DDCMP) for direct computer-to-computer links, supporting various data rates and duplex modes.
• DMP11 and DMF32 Interface Drivers: Explains the DMP11 multipoint DDCMP interface (acting as control or tributary stations) and the DMF32 synchronous line interface, which implements DDCMP in software and supports HDLC bit-stuff mode and character-oriented protocols.
• DR11-W and DRV11-WA Interface Driver: Covers a general-purpose 16-bit parallel DMA data interface used for memory-to-user device or interprocessor links, supporting both block and word transfer modes. The DRV11-WA is specifically for Q-bus systems.
• DR32 Interface Driver: Outlines a high-speed interface adapter that connects a VAX processor's memory bus to the DR32 Device Interconnect (DDI) for rapid 32-bit parallel data transfers, often used in processor-to-processor configurations, featuring command and data chaining.
• Asynchronous DDCMP Interface Driver: Focuses on supporting DDCMP over terminal ports for establishing point-to-point, full-duplex communication lines between VAX processors.

For each driver, the manual elaborates on supported devices, key features (like DMA capabilities, duplex modes, error logging, I/O quotas, and Attention ASTs), methods for obtaining device information, and detailed descriptions of function codes (Read, Write, Set Mode, Sense Mode) including their arguments and modifiers. Programming examples are provided to demonstrate typical usage.