PROC Main()
  BYTE
    i,
    CH=$02FC, ;Internal hardware value for last key pressed
    PALNTSC=$D014, ;To check if PAL or NTSC system is used
    PCOLR0=$02C0,PCOLR1=$02C1,
    PCOLR2=$02C2,PCOLR3=$02C3,
    COLOR0=$02C4,COLOR1=$02C5,
    COLOR2=$02C6,COLOR3=$02C7,
    COLOR4=$02C8

  Graphics(10)
  PCOLR0=$04 ;gray
  PCOLR1=$00 ;black
  IF PALNTSC=15 THEN
    PCOLR2=$42 ;red for NTSC
    PCOLR3=$C6 ;green for NTSC
    COLOR0=$84 ;blue for NTSC
    COLOR1=$66 ;magenta for NTSC
    COLOR2=$A6 ;cyan for NTSC
    COLOR3=$FC ;yellow for NTSC
  ELSE
    PCOLR2=$22 ;red for PAL
    PCOLR3=$B6 ;green for PAL
    COLOR0=$74 ;blue for PAL
    COLOR1=$48 ;magenta for PAL
    COLOR2=$96 ;cyan for PAL
    COLOR3=$EC ;yellow for PAL
  FI
  COLOR4=$0F ;white

  FOR i=0 TO 79
  DO
    Color=i/10+1
    Plot(i,0)
    DrawTo(i,191)
  OD

  DO UNTIL CH#$FF OD
  CH=$FF
RETURN