Remember that:
- TMCC (or Legacy; they are compatible) is a "command" system - you are addressing the locomotive directly, by "name" (that is, number). Obviously you must have the TMCC or Legacy system on your layout (ridiculously simple installation) and locomotives that can receive the signal - that have the proper equipment inside.
Neither TMCC/Legacy nor your 1975 diesel know each other exists. Your Powermaster will run your conventional/PS1 stuff.
- operationally, PS1 locos are "pure" conventional, just as much as one built in 1930 with an e-unit. Variable voltage track, not loco, control. PS1 was not and is not a command system
(PS2/3 can be command systems). They cannot be as "independent" as a command loco -
all will respond to variable track voltage inputs - just like 1955.
- You need a new Lionel CAB1L system - just get the set. Then get a new Powermaster.
You can address your TMCC/Legacy locos with an engine number (using "ENG" button).
This is command control.
For your conventional locos (old or new), you can address your Powermaster ("TR" number), which is simply a "remote conventional throttle" - it's like an electronic connection to an old-fashioned transformer knob or lever. FWD-N-REV.
This is Remote Control of a transformer - not Command Control of a loco.
- You will have to keep your Command and Conventional sessions separate. Actually, you can mix them once you learn how, but, in my opinion, it's dangerous, tedious and, well, stupid.
Anyway: get new "Legacy Lite" system; get new Legacy Powermaster. Follow instructions
for installation and play with it. The light will come on as to how this fits together. You'll smack your forehead and say "Oh! I get it!". No substitute for being there.