INT 10,13 - Write String (BIOS versions from 1/10/86)

	AH = 13h
	AL = write mode (see bit settings below)
	   = 0 string is chars only, attribute in BL, cursor not moved
	   = 1 string is chard only, attribute in BL, cursor moved
	   = 2 string contains chars and attributes, cursor not moved
	   = 3 string contains chars and attributes, cursor moved
	BH = video page number
	BL = attribute if mode 0 or 1 (AL bit 1=0)
	CX = length of string (ignoring attributes)
	DH = row coordinate
	DL = column coordinate
	ES:BP = pointer to string


	Bit settings for write mode (register AL):

	|7|6|5|4|3|2|1|0|  AL
	 | | | | | | | `---- 0=don't move cursor, 1=move cursor
	 | | | | | | `----- 0=BL has attributes, 1=string has attributes
	 `---------------- unused


	returns nothing


	- BEL, BS, CR, LF are treated as ASCII control codes
	- wraps data and scrolls if unable to fit data on one line