The purpose of this book is to give the reader a better understanding of how computers really work at a lower level than in programming languages like Pascal. By gaining a deeper understanding of how computers work, the reader can often be much more productive developing software in higher level languages such as C and C++. Learning to program in assembly language is an excellent way to achieve this goal. Other PC assembly language books still teach how to program the 8086 processor that the original PC used in 1980! This book instead discusses how to program the 80386 and later. | PC Assembly Language Paul A. Carter November 20 2001 Copyright 2001 by Paul Carter This may be reproduced and distributed in its entirety including this authorship copyright and permission notice provided that no charge is made for the document itself without the author s consent. This includes fair use excerpts like reviews and advertising and derivative works like translations. Note that this restriction is not intended to prohibit charging for the service of printing or copying the document. Instructors are encouraged to use this document as a class resource however the author would appreciate being notified in this case. Contents Preface iii 1 Introduction 1 Number Systems. 1 Decimal. 1 Binary. 1 Hexadecimal . 2 Computer Organization. 4 Memory. 4 The CPU. 4 The 80x86 family of CPUs. 5 8086 16-bit Registers. 6 80386 32-bit registers . 7 Real Mode . 7 16-bit Protected Mode . 8 32-bit Protected Mode. 9 Interrupts. 9 Assembly Language . 10 Machine language . 10 Assembly language. 10 Instruction operands. 11 Basic instructions . 11 Directives. 12 Input and Output . 15 Debugging . 16 Creating a Program . 17 First program. 17 Compiler dependencies . 20 Assembling the code . 21 Compiling the C code . 21 Linking the object files . 22 Understanding an assembly listing file. 22
