This Microsoft® Macro Assembler Reference lists all MASM instructions, directives, statements, and operators. It also serves as a quick reference to the Programmer’s WorkBench commands, and the commands for Microsoft utilities such as LINK and LIB. This book documents features of MASM version 6.1, and
is part of a complete MASM documentation set. Other titles in the set are:

Getting Started Explains how to perform all the tasks necessary to install and begin running MASM 6.1 on your system.

Environment and Tools Describes the development tools that are included with MASM 6.1: the Programmer’s WorkBench, CodeView debugger, LINK, EXEHDR, NMAKE, LIB, and other tools and utilities. A detailed tutorial on the Programmer’s WorkBench teaches the basics of creating and debugging MASM code in this full-featured programming environment. A complete list of utilities and error messages generated by ML is also included.

Programmer’s Guide Provides information for experienced assembly-language programmers on the features of the MASM 6.1 language. The appendixes cover the differences between MASM 5.1, MASM 6.0, and MASM 6.1, and the Backus-Naur Form for grammar notation to use in determining the syntax for any MASM language component.


Document Conventions

The following document conventions are used throughout this book:




Uppercase letters indicate filenames, segment names, registers and terms used at the command line.


Bold type indicates text that must be typed exactly as shown. This includes assembly-language instructions, directives, symbols, operators, and keywords in other languages.


Italics indicate variable information supplied by the user.


This typeface indicates example programs, user input, and screen output.

[[optional items]]

Double brackets indicate that the enclosed item is optional.

{choice1 | choice2}

Braces and a vertical bar indicate a choice between two or more items. You must choose one of the items unless double square brackets surround the braces.

Repeating elements...

Three dots following an item indicate that you may type more items having the same form.


Small capital letters indicate key names.