TP(5)                                                                    TP(5)



NAME
       tp - DEC/mag tape formats

DESCRIPTION
       _T_p  dumps  files  to  and extracts files from DECtape and magtape.  The
       formats of these tapes are the same except that  magtapes  have  larger
       directories.

       Block  zero  contains  a  copy of a stand-alone bootstrap program.  See
       _r_e_b_o_o_t(8).

       Blocks 1 through 24 for DECtape (1 through 62 for  magtape)  contain  a
       directory of the tape.  There are 192 (resp. 496) entries in the direc‐
       tory; 8 entries per block; 64 bytes per entry.  Each entry has the fol‐
       lowing format:

              struct {
                      char            pathname[32];
                      unsigned short  mode;
                      char            uid;
                      char            gid;
                      char            unused1;
                      char            size[3];
                      long            modtime;
                      unsigned short  tapeaddr;
                      char            unused2[16];
                      unsigned short  checksum;
              };

       The  path name entry is the path name of the file when put on the tape.
       If the pathname starts with a zero word, the entry is empty.  It is  at
       most  32  bytes long and ends in a null byte.  Mode, uid, gid, size and
       time modified are the same as described under i-nodes (see file  system
       _f_s(5)).   The tape address is the tape block number of the start of the
       contents of the file.  Every file starts on a block boundary.  The file
       occupies  (size+511)/512 blocks of continuous tape.  The checksum entry
       has a value such that the sum of the 32 words of the directory entry is
       zero.

       Blocks above 25 (resp. 63) are available for file storage.

       A fake entry has a size of zero.

SEE ALSO
       fs(5), tp(1)

BUGS
       The _p_a_t_h_n_a_m_e_, _u_i_d_, _g_i_d_, and _s_i_z_e fields are too small.



7th Edition                      May 15, 1985                            TP(5)