INT 10 - VIDEO - WRITE STRING (AT and later,EGA)

	AH = 13h
	AL = write mode
	   bit 0: update cursor after writing
	   bit 1: string contains alternating characters and attributes
	   bits 2-7: reserved (0)
	BH = page number
	BL = attribute if string contains only characters
	CX = number of characters in string
	DH,DL = row,column at which to start writing
	ES:BP -> string to write
Return: nothing
Notes:	recognizes CR, LF, BS, and bell; for the ET4000 BIOS, scrolling,
	  backspace, and CR only take place in the active page
	also available PC or XT with EGA or higher
	HP 95LX only supports write mode 00h
	IBM documents AL=10h,11h,20h,21h as "private" rather than "reserved"
	with PhysTechSoft's PTS ROM-DOS the AL,BH,BL,DH, and DL values are
	  ignored on entry.
BUG:	on the IBM VGA Adapter, any scrolling which may occur is performed on
	  the active page rather than the requested page
SeeAlso: AH=09h,AH=0Ah,AH=13h"DOS/V"