RailSounds 1 was first released in 1989, and the reissue of the Pennsylvania B6 scale switcher was the first to try it out. It consisted of (now) spacious double stack boards that used a hall effect sensor with a magnet in one axle to speed up either the chuff or diesel RPM. The bell and whistle/horn were all the same in every engine that had it, but this system sounded a lot better than the Mighty Sound of Static Steam.
RailSounds 2 was when we first got "engine specific" sounds, like whistles made to be identical to the prototype. It still used a rather spacious power board system.
RailSounds 3 was the beginning of the smaller and more compact 24 pin programmable chip system, which has recently become obsolete at Lionel HQ. This continued into RailSounds 4, which was basically identical, but the chip design was slightly altered. 4E had slightly improved TowerCom - it had both "please stand by" and "clear for departure" dialog.
RailSounds 5 came with (thankfully) clear CrewTalk dialog, and it was multi-part, and was different each time you used it and TowerCom. It even had shut down announcements and moving announcements once the train started moving. This continued into the first Legacy RailSounds systems - 5.5 and 6.0, which had new features like quillible horn/whistle, single hit or continuous bell sounds, start up AND shut down dialog, and emergency stop sequence dialog. 6.0 was the first to offer sequence control, or automatically played RailSounds on the locomotive. The first to have this was (reportedly) the Vision Line scale Hudson.
