VAX/VMS Device Driver Optional Driver Routines

This document, titled "VAX/VMS Device Driver Optional Driver Routines," provides detailed information for developers on implementing various optional routines within a VAX/VMS device driver. It covers several key routines: the Timeout Routine, Powerfail Recovery Routine, Cancel I/O Routine, Controller Initialization Routine, Unit Initialization Routine, and Register Dump Routine.

The document explains when and how each of these routines is invoked by the system, their typical functions, and important considerations for their implementation (e.g., managing IPL levels, restoring resources, handling I/O requests). A significant portion is dedicated to driver error logging, outlining its components, the necessary steps to incorporate error logging capabilities into a driver (including specific macro usage and buffer allocation), and how to interpret error reports generated by the ANALYZE/ERROR_LOG utility. It includes a flow diagram illustrating the error logging process and a sample SYE Error Report. The guide is prepared by Educational Services of Digital Equipment Corporation.