PAL-Timing scheme for a bad scan line, at least the sprites 3-7 active on the
 current scan line and the sprites 0-2 on the following scan line:

  +---------------------------------------------------------------+
  |         1         2         3         4         5         6   |
  |123456789012345678901234567890123456789012345678901234567890123|Cycles
  +---------[------(--------------------------------------)---]---+Borders
  |3s4s5s6s7srrrrrgggggggggggggggggggggggggggggggggggggggg-N0s1s2s|Phi-1 VIC
  |ssssssssss    cccccccccccccccccccccccccccccccccccccccc   ssssss|Phi-2 VIC
  |==========xXXX========================================***======|Phi-2 CPU
  +---------------------------------------------------------------+

  '-' = idle bus cycle (reads from the last byte of the video bank)

   <num> = pointer fetch for sprite <num>  ;  g = graphics fetch
   r = memory refresh cycle  ;  c = character pointer and/or color data fetch
   s = sprite data fetch  ;  N = extra '-' cycles for NTSC added here

   x  = processor executes instructions (BA high, AEC high)
   X  = bus request pending, bus still available (BA low, AEC high);
        processor may execute write cycles, stops on the next read cycle.
  '*' = bus request pending, bus still available (BA low, AEC high);
        processor is blocked because it would like to read something.
  '=' = bus unavailable (BA low, AEC low); processor is blocked because it
        would like to read something.