JS - Jump Signed

	Usage:	JS	label
	Modifies flags: None
	Causes execution to branch to "label" if the Sign Flag is set.
	Signed comparision.
				 Clocks			Size
	Operands	 808x  286   386   486		Bytes
	label:	jump	  16   7+m   7+m    3		 2-4
		no jump	  4	3     3	    1
	- see Instruction Timing