If you can find it, LGB had a 55045 (uses Windows PC and a disk of software) that has a great screen showing all the CV settings on LGB decoders and give the type such as the 55021 which had 3 different versions. Also lets you reprogram the decoder. I have the latest CD software on cd (from approx year 2002). Unfortunately this software is only good for the first 256 (0-255) locations. Perhaps the newer Massoth programmer/software will address these old decoders.