This jumper will allow you to switch from a 500 kHz clock rate to a 1 MHz clock rate that is used only for the Stern's MPU 200 series. So, you only need to move the clock speed jumpers to the left if you're going to be using the new Ultimate MPU in place of a Stern MPU 200 board.This is the setting for just about all of the installed games. All of the Bally and the Stern MPU 100's games should have the jumpers set to the right.This is the jumper setting for just the Stern MPU 200's. If you have a Stern MPU 200 game selected you will move the jumpers to the left.