argto2
o.bytes_per_sector = argto2(optarg, 1, "bytes/sector");
o.directory_entries = argto2(optarg, 1, "directory entries");
o.drive_heads = argto2(optarg, 1, "drive heads");
o.info_sector = argto2(optarg, 1, "info sector");
o.backup_sector = argto2(optarg, 1, "backup sector");
o.reserved_sectors = argto2(optarg, 1, "reserved sectors");
o.sectors_per_track = argto2(optarg, 1, "sectors/track");