INT B3 - ZIPKEY - LOOK UP STATE CODE FOR ZIPCODE                                
	AH = 75h
	DX = zipcode region (0-999)
	CH = last two digits of zipcode (0-99)
Return: CF set on error (zipcode not found)
	    AL = suggested state code, FFh if none
	CF clear if successful
	    AL = ZIPKEY state code
	    BX = area code (v2.0+)
SeeAlso: AH=76h,AH=79h