Function 0FFh   Update Real Display (text mode only)                  (TopView) 

		Update Video Buffer                 (Topview/DesQview/Taskview) 

entry   AH      0FFh 

	CX      number of sequential characters that have been modified 

	DI      offset of first character that has been modified 

	ES      segment of video buffer 

return  unknown 

note 1) DesQview supports this call, but does not require it 

     2) Avoid CX=0