PAL-Timing scheme for a overscan raster line or blanked screen, no sprites:

  +---------------------------------------------------------------+
  |         1         2         3         4         5         6   |
  |123456789012345678901234567890123456789012345678901234567890123|Cycles
  +---------[------(--------------------------------------)---]---+Borders
  |3-4-5-6-7-rrrrr++++++++++++++++++++++++++++++++++++++++-N0-1-2-|Phi-1 VIC
  |                                                               |Phi-2 VIC
  |xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx|Phi-2 CPU
  +---------------------------------------------------------------+

  '-' = idle bus cycle (reads from the last byte of the video bank)
  '+' = idle bus cycle (just like '-', but reads from
        video_bank_base_address + $39FF if ECM ($D011 Bit 6) is selected)

   <num> = pointer fetch for sprite <num>  ;  r = memory refresh cycle
   N = extra '-' cycles for NTSC added here

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