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VAX MACRO

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VAX MACRO
Paradigmsnon-structured, imperative
Familyassembly language
DeveloperDigital Equipment Corporation
First appeared1977; 48 years ago (1977)
Typing disciplineUntyped
ScopeLexical
Implementation languageassembly language
PlatformNative: VAX
With translation: Alpha, Itanium, x86-64
OSVMS
Influenced by
MACRO-11
Influenced
MACRO-64

VAX MACRO is the computer assembly language implementing the VAX instruction set architecture for the OpenVMS operating system, originally released by Digital Equipment Corporation (DEC) in 1977. A significant amount of VMS is written in VAX MACRO.[1]

The syntax, directives, macro language, and lexical substitution operators of VAX MACRO formerly appeared in MACRO-11, the assembler for the PDP-11 series of computers. The MACRO-32 assembler supported the VAX processors developed and manufactured by DEC. It ran under the VMS operating system and produced object files suitable for the VMS linker. The MACRO-32 assembler and linker were bundled with the operating system.

VAX MACRO on other architectures

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The port of VMS to the DEC Alpha architecture led to the creation of a MACRO-32 compiler, which treated VAX MACRO as an input language and generated optimized Alpha object code. The MACRO-32 compiler was necessary since it was not feasible to rewrite the large quantity of VAX MACRO code present in the VMS operating system, layered products, and third-party software.[1] The MACRO-32 compiler was subsequently ported to Itanium and x86-64 as OpenVMS was ported to those architectures.[2][3]

Due to the difficulty of mapping low-level VAX semantics onto other architectures, most VAX MACRO programs written for the native VAX assembler require modification before they can be compiled with the MACRO-32 compiler. These changes include adding directives to explicitly define certain behaviours of the code, and removing code which relies on non-portable constructs.[1] Furthermore, the MACRO-32 compiler allows direct access to certain Alpha architecture features, including Alpha's 32 registers, 64-bit addressing, and a subset of Alpha instructions. These are mapped onto equivalents on Itanium and x86-64, but are not supported by the original VAX MACRO assembler.[4]

The OpenVMS assembler for Alpha assembly code is named MACRO-64. Despite sharing a similar name and macro syntax, MACRO-64 is otherwise unrelated to MACRO-32.[5]

References

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  1. ^ a b c Kronenberg, Nancy P.; Benson, Thomas R.; Cardoza, Wayne M.; Jagannathan, Ravindran; Thomas, Benjamin J. III (1992). "Porting OpenVMS from VAX to Alpha AXP" (PDF). Digital Technical Journal. 4 (4).
  2. ^ "OpenVMS Ask the Wizard – Macro32 Assemblers and Compilers? OpenVMS I64?". 2004-09-09. Retrieved 2025-05-20.
  3. ^ "State of the Port to x86" (PDF). VMS Software Inc. March 2016. Archived from the original (PDF) on 2019-10-29.
  4. ^ "VSI MACRO Compiler User's Guide" (PDF). VMS Software. VMS Software, Inc. 2021. Retrieved 2025-05-20.
  5. ^ "VSI OpenVMS Programming Concepts Manual" (PDF). VMS Software Inc. April 2020. Retrieved 2020-10-07.
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