FileStore Floppy Disc with ADFS
ADT's *DEX to the rescue. Here's sector 0, the beginning of the free space map, which tells us that there are &20 sectors on the disc, which we knew, that the first free space is at sector &20, so it's inaccessible as it is beyond the ADFS portion of the disc, and, significantly, that the NFS First Sector is at &1E, which is within the ADFS bit.