DEBUG REGISTER SUPPORT


            The 80386 processor supports special registers that are used
            for debugging.   Since  the  instructions  to  modify  these
            registers can only be executed by code running at privileged
            level  zero,   protected  mode  debuggers  running  in  DPMI
            environments can  not modify  the registers directly.  These
            services provide  mechanisms for  setting and clearing debug
            watchpoints and  detecting when  a watchpoint  has caused  a
            fault.