INT B3 - ZIPKEY - LOOK UP ZIPCODES FOR A GIVEN STATE AND CITY                   
	AH = 78h
	BL = ZIPKEY state code
	DS:SI -> city name, terminated with 0Dh if complete name, 00h if prefix
Return: BH = number of matching entries (set to 51 if more than 50)
	DX = zipcode region of first match (0-999)
	CL = last two digits of first zipcode in the range (0-99)
	CH = last two digits of last zipcode in the range (0-99)
	AX destroyed
SeeAlso: AH=79h,AH=7Ah