Migrating to an OpenVMS AXP System

This manual provides a comprehensive overview and planning guide for migrating VAX applications to an OpenVMS AXP system. It highlights the compatibility between OpenVMS VAX and OpenVMS AXP while detailing the significant architectural differences between VAX and Alpha AXP.

The document outlines two primary migration paths: recompiling and relinking source code to create native AXP images (offering full AXP performance), or translating VAX binary images using the VAX Environment Software Translator (VEST) and running them under the Translated Image Environment (TIE) (offering VAX compatibility but reduced performance). It emphasizes that translation serves as a safety net when recompilation is impractical or impossible, and discusses combining native and translated images within an application.

Key aspects covered include evaluating an application through inventory and source analysis to identify dependencies on VAX-specific architectural features, such as data alignment, data types (Hfloating, Dfloating), shared data protection (atomicity, granularity), VAX page size assumptions, read/write operation ordering, arithmetic exception reporting, VAX procedure calling standards, AST parameter lists, and explicit reliance on VAX instructions or privileged code.

The manual also details Digital's support services (Orientation, Detailed Analysis, Migration Support, Project Planning, Custom Project, Business Partner Development Assistance Centers) and training programs available to assist with migration. It concludes with practical steps for setting up a migration environment, converting applications, debugging with OpenVMS Debugger or Delta Debugger, rigorous testing (including VAX and AXP-specific tests), and integrating the migrated application into a new software system. An application evaluation checklist and a sample migration plan are included as appendices to aid the planning process.