Hi A fellow named Dallas has a reasonably good DOS that could be adapted to most any other disk configuration. When I get time to fiddle with things, I hope to get the original OS running that came with the FDC-1 used on the SYM-1. My FDC-1 was missing a number of parts. It was only recently that I've been able to collect what I needed. Now, all I need is a little time to bring it together. This DOS is a difficult one to use but the one that Dallas has is a more complete DOS. I beleive it was written by a fellow in Japan. Later Dwight