SUB - Subtract


	Usage:	SUB	dest,src
	Modifies flags: AF CF OF PF SF ZF


	The source is subtracted from the destination and the result is
	stored in the destination.

				 Clocks			Size
	Operands	 808x  286   386   486		Bytes

	reg,reg 	  3	2     2	    1		  2
	mem,reg 	16+EA	7     6	    3		 2-4  (W88=24+EA)
	reg,mem 	 9+EA	7     7	    2		 2-4  (W88=13+EA)
	reg,immed	  4	3     2	    1		 3-4
	mem,immed	17+EA	7     7	    3		 3-6  (W88=25+EA)
	accum,immed	  4	3     2	    1		 2-3


	- see Instruction Timing