SGDT - Store Global Descriptor Table (286+ privileged)

	Usage:	SGDT	dest
	Modifies flags: none
	Stores the Global Descriptor Table (GDT) Register into the
	specified operand.
				 Clocks			Size
	Operands	 808x  286   386   486		Bytes
	mem64		  -	11    9	    10		  5
	- see Instruction Timing