; COM format doesn't have relocation support,
; so you must to tell the assembler to load it in a specific
; memory location, the offset 0100h
org 100h

; this is the binary file section where the data is stored
; our 'data' is just the 'hello world' string
section .data
   hello db 'Hello, World!$', 0

; besides the name (text), this is the section where the actual code is
section .text
   ; print the message to the screen
   ; before 'printing' we must set the parameters first

   ; MOV 9 to the register AH. This means "print string" function
   mov ah, 9
   ; Load the offset address of 'hello world' into register DX
   mov dx, hello

   ; Call the DOS interrupt 21h to execute the function
   int 21h

   ; Exit the program
   ; same thing, move the parameters then execute

   ; AH=4Ch means "exit" function
   mov ah, 4Ch
   ; Set AL to 0 (return code)
   xor al, al

   ; Call the DOS interrupt 21h to exit the program
   int 21h