REPE/REPZ - Repeat Equal / Repeat Zero

	Usage:	REPE
	Modifies flags: None

	Repeats execution of string instructions while CX != 0 and the Zero
	Flag is set.  CX is decremented and the Zero Flag tested after
	each string operation.	 The combination of a repeat prefix and a
	segment override on processors other than the 386 may result in
	errors if an interrupt occurs before CX=0.

				 Clocks			Size
	Operands	 808x  286   386   486		Bytes

	none		  2	2     2			  1

	- see Instruction Timing