Yes, and I crossed from Austria into Czechoslovakia on the train the year before you did, and that’s not quite what I meant. On our train at least, it was stopped, and everyone had to leave the little sitting rooms but stay on the train – mill around in the aisle, in other words – while the authorities inspected the entire train for contraband. (There was a cute girl in my car, looking out the aisle window while standing next to me. A Czech soldier managed to produce from somewhere in that bleak landscape a flower, which he reached up and presented to her.)
No, what I meant was, say, crossing between West European countries, from Switzerland to Germany say, and the train would still be running like normal while Immigration came through to check the passports. They must have boarded at the last stop in the previous country and/or the first stop in the new one.
Aaah, yes that happened also. Although most of the international train trips (starting in Germany) I took, they had to stop at the border. Usually they had to change the engine pulling the train since a lot of the countries had different voltages and frequencies in their electrification. So they used that opportunity to check passports, etc.
Looking here, it seems only Switzerland and Austria could be entered without changing engines, so that would explain not stopping the train on your trip.
