Chapter 1: Introduction to Assembly Language and MASM

Introduction:

Assembly language as a low-level programming language that interacts directly with the hardware

Overview of MASM (Microsoft Macro Assembler) and its role in writing assembly programs

MASM Development Environment:

Installing and configuring MASM for Windows

Setting up a text editor or integrated development environment (IDE) for writing MASM code

Example:

assembly

Copy code

.model small

.stack 100h

.data

    message db 'Hello, World!', 0

.code

main proc

    mov ax, @data

    mov ds, ax

    lea dx, message

    mov ah, 9

    int 21h

    mov ah, 4Ch

    int 21h

main endp

end main

In this example, we start by defining the memory model using the .model directive. We reserve a stack size of 100h bytes using the .stack directive.

In the .data section, we define a null-terminated string called message which holds the text "Hello, World!".

In the .code section, we define the main procedure using the proc and endp directives. Inside the procedure, we load the data segment (@data) into the ax register and then move it to the ds register to set up the data segment.

We use the lea (load effective address) instruction to load the address of the message string into the dx register. Then, we set the value of ah to 9 to indicate the "print string" function of the DOS interrupt 21h. We call the interrupt using int 21h to display the message on the console.

Finally, we use the DOS interrupt 21h with ah set to 4Ch to terminate the program.

By following the explanations and example in this chapter, readers gain a solid understanding of assembly language and MASM. They learn how to set up the MASM development environment and write a simple program that displays a message on the console using DOS interrupts. This sets the foundation for further exploration of assembly language programming and MASM in subsequent chapters.