Nostalgy

  org 100h

section .text
start:
   mov AH, 09h
   lea DX, [CS:msg]
   int 21h

   mov AX, 4C00h; Errorlevel = 0
   int 21h

section .data
   msg DB "Hello World", 0Dh, 0Ah, "$"

section .bss
   ; uninitialized data here

.model tiny
code segment
assume CS:code, DS:code
   org 100h


start:
   mov AH, 09h
   lea DX, [CS:msg]
   int 21h

   mov AX, 4C00h; Errorlevel = 0
   int 21h


   msg DB "Hello World", 0Dh, 0Ah, "$"
code ends
end start

segment code

..start:
   mov AX, data
   mov DS, AX
;   mov AX, stack
;   mov SS, AX
;   mov SP, stacktop

   lea DX, [DS:msg]
   mov AH, 09h
   int 21h

   mov AX, 4C00h
   int 21h

segment data

msg:
   DB "Hello World", 0Dh, 0Ah, "$"

segment stack stack
       resb 256
stacktop:

text segment
   assume CS:text, DS:data

start:
   mov AX, data
   mov DS, AX
   lea DX, [DS:msg]
   mov AH, 09h
   int 21h

   mov AX, 4C00h; Errorlevel = 0
   int 21h

text ends

data segment

   msg DB "Hello World", 0Dh, 0Ah, "$"

data ends

stk segment stack
   DB 256 DUP(0)
ends

end start

; http://www.int80h.org/bsdasm/#system-calls
; nasm -f elf hello2.asm && ld -s -o hello2 hello2.o
%include "system.inc"; Asmutils is required

section .data
hello DB "Hello, World!", 0Ah
hbytes EQU hello

section .text
global _start
_start:
   push dword hbytes
   push dword hello
   push dword stdout
   sys.write

   push dword 0
   sys.exit