Digital Equipment Corporation ALPHA Calling Standard

This document, the "Digital Equipment Corporation ALPHA Calling Standard" (Revision 2.0, April 1990), defines the run-time conventions for native user-mode procedures operating on ALPHA systems in both 64-bit (ALPHA-64) and 32-bit (ALPHA-32) environments.

Key sections of the document include:

• Fundamental Standards: Detailed definitions of data structures, register usage conventions, and flow control (procedure types, call chains, and transfers of control).
• Data Manipulation: Specifications for argument passing mechanisms (immediate value, reference, and descriptor) and data type alignment requirements.
• Event Processing: Procedures for exception handling, including notification, handler invocation, and unwinding.
• Multithreaded Conventions: Design notes for thread-private storage (TPS) and thread environment blocks (TEB).
• Appendices and Implementors Notes: Technical guidance for compiler, runtime library, and operating system developers, as well as notes on compatibility with VAX/VMS and differences from the Extended MIPS calling standard.
• Object File Format: Detailed information on the object file layout, including file headers, section headers, and relocation entries.