anchor.diff:  
   : fb8-toggle-cursor ( -- )
   	line# fb8-line2addr column# fb8-columns2bytes +
  -	char-height 2 - screen-width screen-depth * * +
  +	char-height 2 - screen-line-bytes * +
   	2 0 ?DO
   		dup char-width screen-depth * invert-region
  -		screen-width screen-depth * +
  +		screen-line-bytes +
   	LOOP drop
   ;
   
  
positive.code: : fb8-install ( width height #columns #lines -- )
  	1 to screen-depth
  	2swap  to screen-height  to screen-width
  	screen-#rows min to #lines
  	screen-#columns min to #columns
  	screen-height char-height #lines * - 2/ to window-top
  
negative.code: 	>r
  	fb8-install
  	r> to screen-depth
  	screen-width screen-depth * to screen-line-bytes
  ;
  
  
  