clock : PROCESS

   BEGIN

    C<='0';

     WAIT for 10ns;

     C<='1';

     WAIT for 10ns;

   END PROCESS;



	tb : PROCESS

   BEGIN

		R<='1';
		WAIT FOR 10ns;
		R <='0';
		wait for 10ns;
		x<='0';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;
		x<='0';
		wait for 20 ns;
		x<='1';
		wait for 20 ns;

   END PROCESS;