Alpha Architecture Handbook

This document is the "Alpha Architecture Handbook, Version 3," published in October 1996 by Digital Equipment Corporation. It provides a comprehensive technical reference for the Alpha 64-bit load/store RISC architecture.

The handbook details the architecture's fundamental design, including its approach to RISC principles, data formats (integer and floating-point, including VAX and IEEE standards), register sets, and instruction formats. It extensively describes the instruction set, covering integer and floating-point arithmetic, load/store operations, control, logical, shift, and byte-manipulation instructions, as well as VAX compatibility and multimedia support.

A significant portion of the document is dedicated to system architecture and programming implications, discussing physical address space, memory coherency, caches, data sharing, read/write ordering, and arithmetic traps. It also outlines the Privileged Architecture Library (PALcode) architecture, detailing its functions and instructions specific to OpenVMS Alpha, Digital UNIX, and Windows NT Alpha operating systems. Software considerations for performance optimization and IEEE floating-point conformance are also included.

Notably, this Version 3 introduces:

• New instruction extensions for Byte/Word (BWX), Count (CIX), and Multimedia (MAX) operations.
• Instructions for detecting extension support (AMASK, IMPLVER) and enhancing data-cache efficiency (ECB, WH64).
• Semantic changes to existing LDx_L, STx_C, and WMB instructions.
• Significant updates to Chapter 5 ("System Architecture and Programming Implications") and new tables in Appendix D ("Registered System and Processor Identifiers").