It is resistor R11 on the display board. If you clip it to enable the larger single display rom setup and you experience issues, I highly recommend using a two rom setup. I troubleshot a LW3 a few years ago where I was almost pulling my hair out (all voltages good, ribbon cables good, etc..) and it was simply that the single rom setup on that particular driver board revision simply did not work. (It would show garbled info, work sometimes, etc...)