Int 5F Fn 01  - HP 95lx Graphics Primitives - Set Fill Mask                [b]

   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

See Also: AH=02h