| 1 | .\" @(#)tp5.5 6.1 (Berkeley) %G% |
| 2 | .\" |
| 3 | .TH TP 5 "" |
| 4 | .AT 3 |
| 5 | .SH NAME |
| 6 | tp \- DEC/mag tape formats |
| 7 | .SH DESCRIPTION |
| 8 | .I Tp |
| 9 | dumps files to and extracts files from |
| 10 | DECtape and magtape. |
| 11 | The formats of these tapes are the same except |
| 12 | that magtapes have larger directories. |
| 13 | .PP |
| 14 | Block zero contains a |
| 15 | copy of a stand-alone bootstrap program. |
| 16 | See |
| 17 | .IR reboot (8). |
| 18 | .PP |
| 19 | Blocks 1 through 24 |
| 20 | for DECtape (1 through 62 for magtape) |
| 21 | contain a directory of the tape. |
| 22 | There are 192 (resp. 496) entries in the directory; |
| 23 | 8 entries per block; |
| 24 | 64 bytes per entry. |
| 25 | Each entry has the following format: |
| 26 | .nf |
| 27 | .IP "" |
| 28 | .ta 8n +\w'unsigned short 'u |
| 29 | struct { |
| 30 | char pathname[32]; |
| 31 | unsigned short mode; |
| 32 | char uid; |
| 33 | char gid; |
| 34 | char unused1; |
| 35 | char size[3]; |
| 36 | long modtime; |
| 37 | unsigned short tapeaddr; |
| 38 | char unused2[16]; |
| 39 | unsigned short checksum; |
| 40 | }; |
| 41 | .fi |
| 42 | .DT |
| 43 | .PP |
| 44 | The path name entry is the path name of the |
| 45 | file when put on the tape. |
| 46 | If the pathname starts with a zero word, |
| 47 | the entry is empty. |
| 48 | It is at most 32 bytes long and ends in a null byte. |
| 49 | Mode, uid, gid, size and time modified |
| 50 | are the same as described under i-nodes |
| 51 | (see file system |
| 52 | .IR fs (5)). |
| 53 | The tape address is the tape block number of the start of |
| 54 | the contents of the file. |
| 55 | Every file |
| 56 | starts on a block boundary. |
| 57 | The file occupies (size+511)/512 blocks |
| 58 | of continuous tape. |
| 59 | The checksum entry has a value such that |
| 60 | the sum of the 32 words of the directory entry is zero. |
| 61 | .PP |
| 62 | Blocks above 25 (resp. 63) are available for file storage. |
| 63 | .PP |
| 64 | A fake entry |
| 65 | has a size of zero. |
| 66 | .SH "SEE ALSO" |
| 67 | fs(5), tp(1) |
| 68 | .SH BUGS |
| 69 | The |
| 70 | .I pathname, uid, gid, |
| 71 | and |
| 72 | .I size |
| 73 | fields are too small. |