Jerry, it was free during the (long) beta period. As interest grew and more features were asked for and added, it started taking a lot of Mixy's time to maintain. Since he also has a day job, he decided to convert it to a commercial product and add a limited edition that could still be used for small layouts, hence the 100 track limitation. Being free was nice while it lasted, but with many freeware/shareware programs, they eventually go commercial if the interest and functionality is there. In doing so, he was apparently able to license a version to Atlas with only the Atlas track library and none of the simulation features.
It is interesting to note that the files are interchangeable. That means the Atlas software will open SCARM files, even if they use a different track library, like GarGraves. Furthermore, you can copy/paste the non-Atlas tracks to duplicate them and build a layout that way without the 100-track limit. However, that is a very tedious process and not worth the effort just to save $30-$40 or so. Of course, if you're going to buy SCARM, there's nothing to keep you from looking at the other programs out there, like RR-Track, AnyRail, etc. I still think SCARM is well worth the cost, but that's just me.
