304 lines
13 KiB
Plaintext
304 lines
13 KiB
Plaintext
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A86 assembler package V3.22 January 25, 1990
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The entire package is Copyright 1986--1990 Eric Isaacson.
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All rights reserved.
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PLEASE read Chapter 1 for legal terms and conditions, how to
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register for the package, and the overview of the assembler.
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This manual is huge! A note about printing it occurs at
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the bottom of the next page.
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If you have never heard of "shareware", and you purchased
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this disk from XYZ Software House, that advertises great
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software for $5 per disk, you may now be asking the following
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QUESTION: "What's going on here? Have I already bought an
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assembler, or what?"
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ANSWER: Well, no, not exactly. You've bought a disk that has
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great software on it; you haven't bought the software yet.
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A86, like the vast majority of software offered by the $5-
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per-disk distribution houses, is free-distribution software
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(also known as "shareware", or "user-supported software").
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That means I retain the rights to A86, but I choose to let
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people pass it around. I have no business relationship
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with any distribution houses in the U.S.; I don't get a
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penny of the $5 (or whatever) you paid them for the disk
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containing A86. So I need and expect to be paid by you,
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because I make my living out of making and supporting
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shareware products.
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A few distribution houses do a pretty poor job of revealing
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the shareware nature of the software they sell. If you
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thought you had purchased the software free and clear, you
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might feel justified in being angry with them for having
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misled you. And you might look around for houses that do a
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better job of informing the public. But I hope you'll take
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the time to consider everybody's role in the shareware
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marketing scene; if you do, I think you'll conclude that
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although you may have been misled, you haven't really been
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cheated out of anything.
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Shareware is great for authors like me, who have spent all
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their years in their computer holes, learning to be great
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programmers, and no time in business school learning
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marketing and distribution techniques. We simply cast our
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programs to the winds. They are distributed at practically
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no cost to us. That's why we can charge less than
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the cost of "commercial" software.
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0-2
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Shareware is also great for customers like you. You can
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try out the software before paying for it. You'll know
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that a successful shareware product is good, because only
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satisfied customers pay for it. The existence of shareware
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infuses healthy competition in the entire software market,
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for both price and quality. In the case of A86, I'm
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utterly convinced that you'll never find a better value for
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an assembler, anywhere.
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Finally, let's consider the distribution houses. They
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provide a legitimate service, for which they charge a
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reasonable price. The best houses act as librarians,
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evaluating and cataloguing software. Most pay thousands of
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dollars for advertising. Their cut is far less than the
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distributor's cut for "commercial" software (they prosper
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because their volume is bigger). Most customers for the
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distribution houses are repeat customers, who are aware of,
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and happy with, what they are getting. If it weren't for
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your XYZ House, you might never have heard of A86, or might
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never have figured out where to obtain it.
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So I hope you'll be happy with shareware, and actively
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desire to support it. You'll feel good about promoting a
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healthy situation for everybody. And you'll encourage the
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best programmers in the world to keep writing for you,
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instead of for the big corporations.
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Now that I've said that, let's move on to the package. The
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A86 package consists of the four programs A86.COM, XREF.COM,
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EXMAC.COM, and FAKE.EXE; a collection of source, batch, and
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library files used by the demonstration contained in Chapter
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2, and a sequence of DOC files that, when printed out in
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order, make the manual. Each chapter is a DOC file whose
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name is A??.DOC, where ?? runs from 00 though 17. Exception:
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chapter 6 is split into A06A.DOC and A06B.DOC. The second
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file is wider, and should be printed at 12 cpi if you can
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manage it. The other files can print at 10cpi with margins--
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You should set your printer to a 1-inch left margin, as the
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DOC files do not attempt to provide a left margin for you.
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(You can modify the PAGE.8 program to output the appropriate
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codes!)
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0-3
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TABLE OF CONTENTS
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CHAPTER 1 INTRODUCTION AND LEGAL TERMS
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Introduction 1-1
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Legal Terms and Conditions 1-1
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Registration Benefits 1-3
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Overview of A86 1-4
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About the Author 1-6
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How to Contact Me 1-6
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CHAPTER 2 A86 DEMONSTRATION
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Demonstration of A86 and Associated Tools 2-1
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Assembling a Very Short Program: PAGE.COM 2-1
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Demonstration of Error-Reporting 2-1
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Assembling a Longer Program with Library Files: REV.COM 2-1
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Using XREF on a medium-sized program: TCOLS.COM 2-2
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Using EXMAC 2-2
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CHAPTER 3 OPERATION AND REQUIREMENTS
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Creating Programs to Assemble 3-1
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Program Invocation 3-1
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Assembler Switches 3-2
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The A86 Environment Variable 3-4
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Using Standard Input as a Command Tail 3-5
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Strategies for Source File Maintenance 3-6
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System Requirements for A86 3-6
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CHAPTER 4 ELEMENTS OF THE A86 LANGUAGE
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The A86 Language and the A86 Program 4-1
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General Categories of A86 Elements 4-1
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Operand Typing and Code Generation 4-3
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Registers 4-3
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Variables 4-3
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Labels 4-4
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Constants 4-4
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Generating Opcodes from General Purpose Mnemonics 4-4
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CHAPTER 5 SOME EXCLUSIVE FEATURES OF A86
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The IF Statement 5-1
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Multiple operands to PUSH, POP, INC, DEC 5-1
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Conditional Return Instructions 5-2
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A86 extensions to the MOV and XCHG instructions 5-2
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Local Symbols 5-3
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Operands to AAM and AAD Instructions 5-4
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Single-Operand Forms of the TEST Instruction 5-4
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Optimized LEA Instruction 5-4
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0-4
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CHAPTER 6 THE 86 INSTRUCTION SET
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Effective Addresses 6-1
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Segmentation and Effective Addresses 6-2
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Effective Use of Effective Addresses 6-3
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Encoding of Effective Addresses 6-4
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Table of Effective Address byte values 6-5
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How to Read the Instruction Set Chart 6-6
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The Instruction Set Chart 6-8
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CHAPTER 7 THE FLOATING-POINT PROCESSOR
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The 8087 and 287 Coprocessors 7-1
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Extra Coprocessor Support 7-2
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Emulating the 8087 by Software 7-2
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The Floating Point Stack 7-3
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Floating Point Initializations 7-3
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Built-In Constant Names 7-4
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Special Immediate FLD Form 7-4
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Floating Point Operand Types 7-5
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Operand Choices in A86 7-6
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The 87 Instruction Set 7-6
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CHAPTER 8 NUMBERS AND EXPRESSIONS
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Numbers and Bases 8-1
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The RADIX Directive 8-2
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Floating-point Initializations 8-3
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Overview of Expressions 8-3
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Types of Expression Operands 8-4
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Numbers and Label Addresses 8-4
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Variables 8-4
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Index Expressions 8-4
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Arithmetic Operators 8-4
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HIGH/LOW 8-4
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BY 8-5
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Addition (combination) 8-5
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Subtraction 8-6
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Multiplication and Division 8-6
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Shifting Operators 8-6
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Logical Operators 8-7
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Boolean Negation Operator 8-7
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Relational Operators 8-8
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String Comparison Operators 8-8
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Attribute Operators/Specifiers 8-9
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B,W,D,Q,T Memory Variable Specifiers 8-9
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SHORT and LONG operators 8-9
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OFFSET operator 8-10
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NEAR Operator 8-11
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Square Brackets Operator 8-11
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Colon Operator 8-11
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ST Operator 8-12
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TYPE Operator 8-12
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THIS and $ Specifiers 8-12
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Operator Precedence 8-13
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0-5
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CHAPTER 9 DIRECTIVES IN A86
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Segments in A86 9-1
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CODE ENDS and DATA ENDS Statements 9-2
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The ORG Directive 9-2
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The EVEN Directive 9-3
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Data Allocation Using DB, DW, DD, DQ, and DT 9-3
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The STRUC Directive 9-6
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Forward References 9-6
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Forward References in Expressions 9-7
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The EQU Directive 9-8
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Equates to Built-In Symbols 9-9
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The NIL Prefix 9-9
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Interrupt Equates 9-9
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Duplicate Definitions 9-9
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The = Directive 9-10
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The PROC Directive 9-10
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The ENDP Directive 9-11
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The LABEL Directive 9-11
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CHAPTER 10 RELOCATION AND LINKAGE
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.OBJ Production Made Easy 10-1
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Overview of Relocation and Linkage 10-3
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The NAME Directive 10-5
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The PUBLIC Directive 10-5
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The EXTRN Directive 10-6
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MAIN: The Starting Location for a Program 10-7
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The END Directive 10-7
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The SEGMENT Directive 10-8
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DATA SEGMENT, STRUC and CODE SEGMENT Directives 10-11
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The ENDS Directive 10-11
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Default Outer SEGMENT 10-12
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The GROUP Directive 10-12
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The SEG Operator 10-13
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0-6
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CHAPTER 11 MACROS AND CONDITIONAL ASSEMBLY
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Macro Facility 11-1
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Simple Macro Syntax 11-1
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Formatting in macro definitions and calls 11-2
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Macro operand substitution 11-2
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Quoted-string operands 11-3
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Looping by operands in macros 11-4
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The #L last operator and indefinite repeats 11-5
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Character-loops 11-5
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The "B"-before and "A"-after operators 11-6
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Multiple-increments within loops 11-6
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Negative R-loops 11-7
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Nesting of loops in macros 11-8
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Implied closing of loops 11-8
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Passing Operands by Value 11-8
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Passing Operand Size 11-8
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Generating the Number of an Operand 11-9
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Parenthesized Operand Numbers 11-9
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Exiting from the Middle of a Macro 11-10
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Local labels in macros 11-10
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Debugging macro expansions 11-11
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Conditional Assembly 11-11
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Conditional Assembly and Macros 11-13
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Simulating MASM's Conditional Assembly Constructs 11-14
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Conditional Assembly and the XREF Program 11-14
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Declaring Variables in the Assembler Invocation 11-14
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Null Invocation Variable Names 11-15
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Changing Values of Invocation Variables 11-15
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CHAPTER 12 COMPATIBILITY WITH OTHER ASSEMBLERS
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Conversion of MASM programs to A86 12-1
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Compatibility-symbols recognized by A86 12-4
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Conversion of A86 Programs to Intel/IBM/MASM 12-5
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CHAPTER 13 ASSOCIATED TOOLS
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XREF Cross-reference and Symbol Listing Facility 13-1
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EXMAC Macro Expansion Tool 13-2
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A86LIB Source File Library Tool 13-3
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Using A86.LIB in A86 Assemblies 13-4
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Environment Variable A86LIB 13-5
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Forcing a Library Search 13-5
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Listings with A86 13-5
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Mimicking Tool: FAKE.EXE 13-7
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CHAPTER 14 DESCRIPTIONS OF A86 ERROR MESSAGES
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CHAPTER 15 RELEASE HISTORY OF A86
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CHAPTER 16 RESERVED SYMBOLS IN THE A86 LANGUAGE
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INDEX
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