DECLARE SUB initcol (a&, b&)
DEFINT A-Z
SCREEN 13
bigx = 20
bigy = 12
initcol 256, 65536
FOR startx = 0 TO bigx - 1
  stopx = startx + ((bigx * 16) - 1)
  FOR starty = 0 TO bigy - 1
  stopy = starty + ((bigy * 16) - 1)
    FOR x% = startx TO stopx STEP bigx
      FOR y% = starty TO stopy STEP bigy
        PSET (x%, y%), c%
        c% = (c% + 1) MOD 256
        FOR delay = 1 TO INT(40000 / (bigx * bigy))
        NEXT delay
      NEXT y%
    NEXT x%
  NEXT starty
NEXT startx

DO
  initcol 256, 1
  initcol 65536, 1
  initcol 65536, 256
  initcol 1, 256
  initcol 1, 65536
  initcol 256, 65536
LOOP UNTIL INKEY$ <> ""

SUB initcol (a&, b&)

FOR x% = 0 TO 63 STEP 4
  FOR y% = 0 TO 63 STEP 4
        PALETTE c%, a& * x% + b& * y%
        c% = (c% + 1) MOD 256
        IF INKEY$ <> "" THEN END
  NEXT y%
NEXT x%

END SUB