
out $bf,$80:out $bf,%00100000
out $bf,$81:out $bf,%00000011
out $bf,$86:out $bf,%00000100

VDP Register 0
  bit 76543210
      ||||||||
      |||||||+-0: Screen sync off
      ||||||+--1: Enable stretch screen (33 columns wide)
      |||||+---2: ?
      ||||+----3: Shift all sprites left by 1 character
      |||+-----4: Enable line interrupt IRQ's (see VDP Register 10)
      ||+------5: Do not display leftmost column of the screen
      |+-------6: Top 2 rows of screen not affected by horizontal scrolling
      +--------7: Right hand 8 columns of screen not affected by vertical scrolling

      
VDP Register 1
  bit 76543210
      xxxxxxxx
      ||||||||
      |||||||+-0: Zoomed sprites; all pixels in all sprites are doubled in size
      ||||||+--1: 8x16 sprites; when this bit is 0, the default 8x8 sprites are used
      |||||+---2: ?
      ||||+----3: Extend screen by 6 rows (i.e. to 30 rows)
      |||+-----4: Extend screen by 4 rows (i.e. to 28 rows)
      ||+------5: Enable VSync interrupt generation (IRQ)
      |+-------6: Enable display; no picture is shown when this bit is 0
      +--------7: ?

      
VDP Register 6
   bit  7 6 5 4 3 2 1 0
        x x x x x d x x
      where if d=0, all sprites use tiles defined from $0000 (i.e. tiles 0..255)
         or if d=1, all sprites use tiles defined from $2000 (i.e. tiles 256..511).
         
VDP Register 8
   x scroll offset

VDP Register 9
   y scroll offset
