INT 50 - Vanderaart TEXT WINDOWS - OUTPUT LINE TO WINDOW                        
	AX = 0003h
	ES:BX -> text string
	CX = string length (0000h if ASCIZA NUL-terminated ASCII string.	The ASCIZ string "ABC" consists of the four bytes 41h, 42h, 43h, and 00h.  Unless otherwise specified, maximum lengths given in the interrupt list do not include the terminating NUL. string)
	DL = position (FFh centered, else flush left)
	DH = starting row
	DI = window handle
Return: AX = status
	    0000h successful
	    FFFFh did not fit in window