RE: How do you know if pcm radio?
Generally, the Tx would have PCM printed on the case somewhere. If it was a computer radio, you would see PCM or PPM in the display somewhere. Futaba had a Conquest radio that was PCM only and it was not a computer radio, but usually, it will be marked somewhere on the Tx case.
Most PCM computer radios can be switched from PCM to PPM in the Modulation section of the Model Memory. You need PPM for Flight Simulators, as well.