There's something I'm not clear on ... is it possible to have both a Keil Tools-based target and a GNU Tools-based target in the same project? I tried it, and it seems that because of the substantially different Startup.s for Keil vs GNU, it's not possible to do this. E.g. I had a project with only a Keil-based target. In this project I created a new / additional target for use with GNU. Building the GNU target failed because of lots of syntax errors in Startup.s (which came from a Keil project, of course). So In the GNU target, I removed Startup.s and replaced it with the one from the GNU Blinky, so that it would build under GNU. But now it fails under Keil because of the same problem ... Are the files in the filelist always the same across all of the targets? I.e. a project's filelist is not target-specific? Thanks,