    clear\n\n    # Draw the background grid\n    if showGrid == 1 begin\n      plane 2\n      i := grid\n      v0 := 0\n      v1 := 0\n      v2 := 32\n      loop\n        sprite v0 v1 0\n        i += v2\n        v0 += 16\n        if v0 == 128 begin\n          v0 := 0\n          v1 += 16\n        end\n        if v1 != 64 then\n      again\n    end\n\n    # Draw the containing box\n    plane 1\n    v0 := marginX\n    v0 -= 2\n    v1 := marginY\n    v1 -= 2\n    v2 := 65\n    v2 -= marginY\n    v3 := 129\n    