whoops system 3
yes you need to use dip switches.
i am trying to figure out how to set it to free play.

Press diagnostic button (bottom button on mpu board) and check leds flash twice and displays are blank.
Set function dip switch (bottom set of dip switches on mpu) 6 on, 8 on and all others off
set data dip switch (top set of dip switches on mpu) to all off (which =00)
press enter button (top button on mpu board) and check leds flash once.

hope this works for you. i have worked this out by reading a system 3 user manual