I've downloaded several ks10 instruction set diagnostics in .SAV file format from trailing-edge.com. In a 36-bit world, I think I understand the .SAV file format. I can't figure out the format that I've retrieved. I've even tried loading the .SAV files that I've retrieved into SIMH but SIMH complains about a "Format Error". Any clues? Did I mung the files copying them from the website? Rob.