     PAL-Timing scheme for a normal scan line, no sprites:

      +---------------------------------------------------------------+
      |         1         2         3         4         5         6   |
      |123456789012345678901234567890123456789012345678901234567890123|Cycles
      +---------[------(--------------------------------------)---]---+Borders
      |3-4-5-6-7-rrrrrgggggggggggggggggggggggggggggggggggggggg--0-1-2-|Phi-1 VIC
      |                                                               |Phi-2 VIC
      |xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx|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

       x = processor executes instructions (BA high, AEC high)