Assembly "Hello, world!"

stack SEGMENT STACK
         DB 256 DUP(?)

stack ENDS

data SEGMENT
        msg DB 'Hello, world!$'

data ENDS

code SEGMENT
         ASSUME CS:code,DS:data,SS:stack
START:
         MOV AX,data
         MOV DS,AX
         MOV DX,OFFSET msg
         MOV AH,9H
         INT 21H
         MOV AH,4CH
         INT 21H
  
code ENDS
END START