VERW - Verify Write (286+ protected)

	Usage:	VERW	src
	Modifies flags: ZF


	Verifies the specified segment selector is valid and is ratable
	at the current privilege level.  If the segment is writable,
	the Zero Flag is set, otherwise it is cleared.


				 Clocks			Size
	Operands	 808x  286   386   486		Bytes

	reg16		  -	14    15    11		  3
	mem16		  -	16    16    11		  5


	- see Instruction Timing