ON ERROR IF ERR=17 CHAIN @lib$+"../examples/tools/touchide" ELSE MODE 3 : PRINT REPORT$ : END
      
      REM Munching squares: an attractive pattern resulting simply from the
      REM exclusive-or function of the horizontal and vertical coordinates.
      
      W% = 512
      VDU 23,22,W%;W%;8,16,16,0 : OFF
      
      FOR X% = 0 TO W%-1
        FOR Y% = 0 TO W%-1
          B% = (X% EOR Y%) AND 255
          COLOR 7, B%, B%>>1, 255-B%
          PLOT 2*X%, 2*Y%
        NEXT
      NEXT
      
      REPEAT WAIT 10 : UNTIL FALSE
      END