These constants are used to test the individual flag bits in the
      FLAG register.  This is performed after a call to the Intr or MsDos
      procedures.

                       FCarry       = $0001;
                       Fparity      = $0004;
                       FAuxilliary  = $0010;
                       FZero        = $0040;
                       FSize        = $0080;
                       FOverflow    = $0800;