stack_ segment page stack 'stack'
       org 0100h
stack_ ends
data_  segment page 'data'
       org 0100h
data_  ends
code_  segment page 'code'
       assume ss:stack_, ds:data_, cs:code_
start:
       mov dx,03d8h
       mov ax,1dh
       out dx,ax
       ret
code_  ends
       end      start

