10 REM > Boxes
   20 REM Creates rectangles to show different colours
   30 MODE 27:REM use mode 12 for standard resolution monitor
   40 ON ERROR REPORT:PRINT " at line ";ERL:END
   50 FOR colour%=7 TO 0 STEP -1
   60   GCOL colour%
   70   RECTANGLE FILL 600-colour%*60,400-colour%*50,120+colour%*120,100+colour%*100
   80 NEXT
   90 GCOL 7
  100 CIRCLE 660,450,300