function GetPortAddress(PortNo: integer): word; assembler; stdcall;
asm
  push es
  push ebx
  mov ebx, PortNo
  shl ebx,1
  mov ax,40h // Dos segment adress
  mov es,ax
  mov ax,ES:[ebx+6] // get port adress in 16Bit way :)
  pop ebx
  pop es
end;