Ausam/doc/man/man4/tm.4

.th TM IV 25/1/78
.sh NAME
tm \*- TM11/TS03 800bpi magnetic tape interface
.sh DESCRIPTION
The file
.it mt0
refers to the TS03 tape drive.
When opened for reading or writing, the tape is rewound.
If the last operation was a write, two tape marks (\ EOI\ )
are written when the file is closed.
The file
.it mt8
is not rewound on open,
but, if an EOI has just been written,
the tape is moved back one tape mark.
The file
.it mt1
is a link to
.it mt8.

A standard tape consists of consecutive 512 byte
records terminated by 2 tape marks,
however,
in multi-file tapes,
the files are seperated by one tape mark (\ EOF\ ).
To the extent possible, the system makes it possible,
if inefficient, to treat the tape like any other 
file.
Seeks have their usual meaning and it is possible to read
or write a byte at a time.

The file
.it rmt0
opens the tape drive as a raw special file
and rewinds the tape.
Each read or write deals with the next record on the tape.
In the write case the record has the same length as the buffer given.
During a read the record size is passed back as the number of bytes
read, provided it is no greater than the buffer size;
if the record is long, an error is indicated.
In raw tape i/o, the buffer must begin on a word boundary
and the count must be even.
Seeks are ignored.
Tape marks will read as EOF (\ zero bytes read\ ),
but another read will fetch the next record on the tape.
The file
.it rmt8
is not rewound on open, but is otherwise the same.

Stty calls may be directed to the raw special files.
Only the first two integer arguments are significant: the
first one selecting the action, and the second one a count.
.s3
.lp +21 10
0:	Skip forward file
.lp +21 10
1:	Skip reverse file
.lp +21 10
2:	Unused
.lp +21 10
3:	Write tape mark
.lp +21 10
4:	Skip forward block
.lp +21 10
5:	Skip reverse block
.lp +21 10
6:	Drive off line
.lp +21 10
7:	Rewind
.i0
.dt
.sh FILES
/dev/mt?, /dev/rmt?
.sh "SEE ALSO"
tp(I), itp(I), stp(I), stty(II)
.sh BUGS
If any non-data error is encountered,
it refuses to do anything until closed.