The hardware of early Cinematronics and Vectorbeam CPUs implemented an instruction, Jump on External High (JEH). JEH branched if an input from the game's soundboard (connected to J4-10 on the CCPU) was logic level HIGH. This instruction was used only once, for reading the joystick in Tailgunner.
Later boards replaced this instruction with a more useful one: Jump on Minus (JMI) which branches when the result of the preceeding calulation is negative. These boards include a jumper that can be removed to allow the use of JEH and disabiling the JMI instruction.
The list below was compiled after searching the code of all the Vectorbeam and Cinematronics games for use of JMI and JEH:
These games can run on a board without JMI: (Confirmed on Tailgunner Hardware)
Space War / Space Wars (no JMI or JEH instructions)
Speed Freak (no JMI or JEH instructions)
All others require JMI to be installed to run:
Rip Off (JMI)
Star Castle (JMI)
Armor Attack (JMI)
Solar Quest (JMI)
Boxing Bugs (JMI)