architecture bada of bing is
    subtype nat16_t : natural range 0 to 65535;
    constant A_BASE : nat16_t := X"F000";
    constant A_TOP  : nat16_t := X"F0FF";
    signal myaddr   : nat16_t;
    signal select   : std_logic;
begin
    select <= '1' when (myaddr >= A_BASE) and 
                       (myaddr <  A_TOP) else
              '0';
end architecture bada;