tm(4) [v7 man page]
TM(4) Kernel Interfaces Manual TM(4) NAME
tm - TM-11/TU-10 magtape interface DESCRIPTION
The files mt0, ..., mt7 refer to the DEC TU10/TM11 magtape. When closed it can be rewound or not, see below. If it was open for writing, two end-of-files are written. If the tape is not to be rewound it is positioned with the head between the two tapemarks. If the 0200 bit is on in the minor device number the tape is not rewound when closed. A standard tape consists of a series of 512 byte records terminated by an end-of-file. To the extent possible, the system makes it possi- ble, 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. Writing in very small units is inadvisable, however, because it tends to create monstrous record gaps. The mt files discussed above are useful when it is desired to access the tape in a way compatible with ordinary files. When foreign tapes are to be dealt with, and especially when long records are to be read or written, the `raw' interface is appropriate. The associated files are named rmt0, ..., rmt7. Each read or write call reads or writes 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. A zero byte count is returned when a tape mark is read, but another read will fetch the first record of the new tape file. FILES
/dev/mt?, /dev/rmt? SEE ALSO
tp(1) BUGS
If any non-data error is encountered, it refuses to do anything more until closed. In raw I/O, there should be a way to perform forward and backward record and file spacing and to write an EOF mark. TM(4)
Check Out this Related Man Page
HT(4) Kernel Interfaces Manual HT(4) NAME
ht - TM-03/TE-16,TU-45,TU-77 MASSBUS magtape interface SYNOPSIS
/sys/conf/SYSTEM: NHT ht_drives # TE16, TU45, TU77 /etc/dtab: #Name Unit# Addr Vector Br Handler(s) # Comments ht ? 172440 224 5 htintr # tu 16 massbus tape major device number(s): raw: 6 block: 0 minor device encoding: bits 0003 specify HT drive bit 0004 specifies no-rewind operation bit 0010 specifies 1600BPI recording density instead of 800BPI DESCRIPTION
The tm-03/transport combination provides a standard tape drive interface as described in mtio(4). All drives provide both 800 and 1600 bpi; the TE-16 runs at 45 ips, the TU-45 at 75 ips, while the TU-77 runs at 125 ips and autoloads tapes. FILES
/dev/MAKEDEV script to create special files /dev/MAKEDEV.local script to localize special files SEE ALSO
mt(1), tar(1), tp(1), mtio(4), tm(4), ts(4), dtab(5), autoconfig(8) DIAGNOSTICS
tu%d: no write ring. An attempt was made to write on the tape drive when no write ring was present; this message is written on the termi- nal of the user who tried to access the tape. tu%d: not online. An attempt was made to access the tape while it was offline; this message is written on the terminal of the user who tried to access the tape. tu%d: can't change density in mid-tape. An attempt was made to write on a tape at a different density than is already recorded on the tape. This message is written on the terminal of the user who tried to switch the density. tu%d: hard error bn%d er=%b ds=%b. A tape error occurred at block bn; the ht error register and drive status register are printed in octal with the bits symbolically decoded. Any error is fatal on non-raw tape; when possible the driver will have retried the operation which failed several times before reporting the error. BUGS
If any non-data error is encountered on non-raw tape, it refuses to do anything more until closed. The system should remember which controlling terminal has the tape drive open and write error messages to that terminal rather than on the console. 3rd Berkeley Distribution January 28, 1988 HT(4)