I don’t think you are quite correct abacus, unless you are talking specifically about the Prelude, which I have no knowledge of.

Yes, bare PC#’s will select the Capital Tone (sound) of that number on just about anything. But WAY before the Prelude (Sound Canvas, I think, maybe even the MT-32) selected tones other than the Capitol Tone (the first one of any Variations) by preceding the PC command with two controller values, CC’s 00 and 32 (Controller MSB/LSB) which then multiplied the voice choices exponentially.

So much, in fact, that Roland could now start selecting Registrations with a single string of commands, even up to the 999 entry BK series Performance list. So a call for a Registration will NEVER get confused with a call for a Program change.

I think the Prelude was a sort of side project arranger to the crossover period between the G/E series and the ten years later BK. So it’s possible that maybe the codes for the UPG’s in it might be the same as either the G series or the BK series. Worth a try, at least!

On another note, I think this was the first Roland arranger to allow mp3/Wav playback from a memory card, quite a while before the BK7m and the subsequent BK arrangers.