anchor.diff:         (top-ntaddr  (zp #x97))
          (vblank-flag (zp #x96)))         ; Set by NMI handler.
   
  -  (emit music)
  -
     (procedure reset
       (sei)
       (cld)
  
positive.code:         (dey))
        (dec fill-count)))
  
    ;; Wasteful, but the ROM is mostly empty anyway.
    (procedure fill-attributes
      (dotimes (y 8)
        (dotimes (x 4) (sty (mem +vram-io+)))
        (dotimes (x 4) (sta (mem +vram-io+))))
      (rts))
  
    (procedure initialize-sprites
  
negative.code: 
      ;; Wavy effect
      (flet ((kernel ()
               (poke #b11111110 +ppu-cr2+)
               (clc)
               (lda wt-get)               ; Get wave offset
               (adc scroll-x)             ; Add to BG scroll position
  