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ht(4) [bsd man page]

HT(4)							     Kernel Interfaces Manual							     HT(4)

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)

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HT(4)							     Kernel Interfaces Manual							     HT(4)

ht - RH-11/TU-16 magtape interface DESCRIPTION
The files mt0, mt1, ... refer to the DEC RH/TM/TU16 magtape. When opened for reading or writing, the tape is not rewound. When closed, it is rewound (unless the 0200 bit is on, see below). If the tape was open for writing, a double end-of-file is written. If the tape is not to be rewound the tape is backspaced to just between the two tapemarks. A standard tape consists of a series of 512 byte records terminated by a double end-of-file. 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. Writing in very small units is inadvisable, however, because it tends to create monstrous record gaps. The last octal digit of the minor device number selects the drive. The middle digit selects a controller. The initial digit is even to select 800 BPI, odd to select 1600 BPI. If the 0200 bit is on (initial digit 2 or 3), the tape is not rewound on close. Note that the minor device number has no necessary connection with the file name, and in fact tp(1) turns the short name x into `/dev/mtx'. 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 may be named rmt0, ..., rmt7, but the same minor-device considerations as for the regular files still apply. 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 count is returned when a tape mark is read; another read will fetch the first record of the next tape file. FILES
/dev/mt?, /dev/rmt? SEE ALSO
tp(1) BUGS
The magtape system is supposed to be able to take 64 drives. Such addressing has never been tried. Taking a drive off line, or running off the end of tape, while writing have been known to hang the system. 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 explicitly. HT(4)
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