GGG,
I typically use the Roman Numerals of I and II to differentiate between the numbers 2.0 and beyond. If you look at the Lionel parts site, this is how I architected all the part descriptions. Railsounds II (as mentioned above in the Conrail SD60M, Rio Grande SD50, etc) were all conventional application only sounds. When Railsounds 2.0 was introduced it was coupled with the LCRU I (and later the LCRU II), which gave the sounds the command capability.
I never attempted to swap Railsounds II PIC and ROM's into a RS 2.0 platform, however, if memory serves me correctly Bob Jacobsen over at Electric Train Outlet in St Louis, MO had done this with the Conrail SD60M chips (and let me tell you how AWESOME it sounded!). Actually made me take a step back, that earlier RS II sound set had command control capability! (ability to decipher serial data in the PIC) I never tried it personally (or professionally) but having heard it first hand it is obviously feasible!).
All that being said, for the average consumer / tinkerer out there I would use the differentiation of the roman numerals versus the numbering sequence as the break point in compatibility. Meaning keep the RS I and RS II in their intended conventional world and keep the RS 2.0, 2.5, 3.0 and beyond in their command world, if for nothing more than simplicity and keeping some hair!
Wasn't part of this that RS up through and including RS 2.0 were conventional only?
To be fair, yes. All command controlled locos will operate in conventional mode, hence the sound systems will as well. However, Lionel has a slew of "conventional only" soundboards over the years, which was not part of the outline above. These are sounds used in starter set and entry level conventional only (not command upgradeable) applications. That is what the reference is to, not command sounds being used in a conventional environment. For clarification purposes, your question above is misleading. It should read; Wasn't part of this that RS up through and including RS II were conventional only? the answer would be yes. to follow that question up, Railsounds 2.0 was the introduction of command compatible sounds (meaning it deciphered serial communications).
RS2.5 was the first TMCC based RS and that was in the early NYC/SP GP-9?
This was actually Railsounds 2.0 (no Towercom or Crewtalk) coupled with an LCRU II. Railsounds 2.5 was the same exact hardware, it just added Towercom and Crewtalk to the feature set. The photo below is the platform that came in those early geeps (Railsounds 2.0 and LCRU II);
(The part number is not correct for the NYC / SP geeps, but the photo is accurate (and the bracketry). The part number above is the B&M GP-9, same generation, but came equipped with coil couplers.
If we could keep roman numerals and numbers as the delineation point it would make things much easier to follow.
Hope this helps clear that up!
Thanks,
Mike
