INT 21 - Novell NetWare shell 3.01 - TASK MODE CONTROL
        AH = B5h
        AL = subfunction
            03h get task mode
                Return: AH = 00h
                        AL = current task mode byte
            04h get task mode pointer
                Return: ES:BX -> task mode byte
Notes:  the task mode byte specifies how task cleanup should be performed, but
          is declared to be version-dependent
        allows a program to disable the automatic cleanup for programs managing
          task swapping, etc.

Values for task mode byte in version 3.01:
 00h-03h reserved
 04h     no task cleanup