argto2
opt_S = argto2(optarg, 1, "bytes/sector");
opt_e = argto2(optarg, 1, "directory entries");
opt_h = argto2(optarg, 1, "drive heads");
opt_i = argto2(optarg, 1, "info sector");
opt_k = argto2(optarg, 1, "backup sector");
opt_r = argto2(optarg, 1, "reserved sectors");
opt_u = argto2(optarg, 1, "sectors/track");