NAME
tp - DEC/mag tape formats
DESCRIPTION
The command tp dumps files to and extracts files from DEC-
tape 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 pro-
gram. See boot procedures (VIII).
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 directory; 8 entries per block; 64 bytes per
entry. Each entry has the following format:
path name 32 bytes
mode 2 bytes
uid 1 byte
gid 1 byte
unused 1 byte
size 3 bytes
time modified 4 bytes
tape address 2 bytes
unused 16 bytes
check sum 2 bytes
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 (file system (V)). The tape
address is the tape block number of the start of the con-
tents 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 25 (resp. 63) on are available for file storage.
A fake entry (see tp (I)) has a size of zero.
SEE ALSO
file system (V), tp (I)
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