INT 5F - HP 95LX/100LX/200LX GRAPHICS PRIMITIVES - SET FILL MASK                
	AH = 01h
	ES:DI -> 8-byte fill mask
Note:	the fill mask represents an 8x8 pixel box and is repeated as necessary
	  when drawing filled rectangles; it is always aligned with the byte
	  boundaries of video memory, regardless of the actual boundaries of
	  the rectangle
SeeAlso: AH=02h