LOCK - Lock Bus

	Usage:	LOCK
		LOCK: (386+ prefix)
	Modifies flags: None

	This instruction is a prefix that causes the CPU assert bus lock
	signal during the execution of the next instruction.  Used to
	avoid two processors from updating the same data location.  The
	286 always asserts lock during an XCHG with memory operands.  This
	should only be used to lock the bus prior to XCHG, MOV, IN and
	OUT instructions.

				 Clocks			Size
	Operands	 808x  286   386   486		Bytes

	none		  2	0     0	    1		  1

	- see Instruction Timing