Me, on accident, after forgetting to reset it after exiting Metroid. Dux pointed out using HL instead of IY for size. > ld hl, $c3e5+new_grf_flgs > ld a, 2<<textwrite > xor (hl) > ld (hl),a > 7 bytes and 31 cycles (+ the ret) > i have no idea who originally thought of that