Unofficial Tech Support Response to "Vex Motors"

You can use Y Cables. A base with four motors can take up two ports instead of 4. How is that possible? Like I said Y Cables. It’s illegal however to connect Y Cables to each other. Also, pneumatics take up 2 motors if you decide to use them. So 12 motors max because you can still use all 10 possible motors for each of the motor ports AND have pneumatics. Hope this answers your question.
P.S. Next time put the channel to unofficial because it allows other forum users like myself to answer.

I would suggest aginst using ports 1 and 10. There’s no protection to the cortex for those port. If you use 2 through 9 the motor controller keeps you from ruining your cortex if a motor shorts.

@Tegicupala, as @bwilfong2018 states ports 1 and 10 are different. They are two-wire ports, and the motor controller circuit is built in to the Cortex for them. The concern he references is that faulty motor wiring (a short across the two motor wires) will cause the failure of electronic parts that are soldered on to the VEX Cortex circuit board. The same failure on ports 2-9 will still cause a component to fail. In that case, though, it is an external 3-wire motor controller. While it’s still a shame to have bad wiring ruin a part, at least with ports 2-9 it is an external part which is easily replaced.

However, even if you fry motor port 1 or 10, my experience is that the rest of the Cortex will still function fine. So, it’s less of a problem than it at first seems. Because you can either avoid using those two ports for fear that you might cause them to fail, or you can use them until they fail.