Free Real Mode Call-Back Address


                 This function  frees a real mode call-back address that
                 was allocated  through the allocate real mode call-back
                 address service.

            To Call

                 AX = 0304h
                 CX:DX = Real mode call-back address to free

            Returns

                 If function was successful:
                 Carry flag is clear.

                 If function was not successful:
                 Carry flag is set.

            Programmer's Notes

                 o    Real mode call-backs are a limited resource.  Your
                      code should  free any  break point  that it  is no
                      longer using.