LET w = 640
LET h = 480
SET WINDOW 0, w, 0, h

LET h = h/4
LET y2 = h-1

FOR i = 1 to 4
    LET col = 0
    LET y = (i-1)*h
    FOR x = 1 to w step i
        IF remainder(col,15) = 0 then LET col = 0
        SET COLOR col
        BOX AREA x, x+i, y, y+h
        LET col = col+1
    NEXT x
NEXT i
END