Return to ht.4 CVS log

Up to [CSRG BSD Unix] / 40BSD / sys / newsys

Annotation of 40BSD/sys/newsys/ht.4, revision 1.1.1.1

1.1       root        1: .TH TM 4 
                      2: .SH NAME
                      3: ht \- RH-11/TE-16 magtape interface
                      4: .SH DESCRIPTION
                      5: The files
                      6: .I "mt0, ..., mt15"
                      7: refer to the DEC RH/TM/TE-16 magtape.
                      8: Even numbered files are
                      9: 800 bpi, and
                     10: odd numbered files are
                     11: 1600bpi.
                     12: The files
                     13: .I "mt0, ... mt15"
                     14: unlike the files
                     15: .I "nmt0, ... nmt15,"
                     16: which are not.
                     17: When a file open for writing is closed, a double end-of-file is written.
                     18: .PP
                     19: A standard tape consists of a
                     20: series of 512 byte records terminated by an
                     21: end-of-file.
                     22: To the extent possible, the system makes
                     23: it possible, if inefficient, to treat
                     24: the tape like any other file.
                     25: Seeks have their usual meaning and it is possible
                     26: to read or write a byte at a time.
                     27: Writing in very small units is inadvisable,
                     28: however, because it tends to create monstrous record
                     29: gaps.
                     30: .PP
                     31: The
                     32: .I mt
                     33: files discussed above are useful
                     34: when it is desired to access the tape in a way
                     35: compatible with ordinary files.
                     36: When foreign tapes are to be dealt with, and especially
                     37: when long records are to be read or written, the
                     38: `raw' interface is appropriate.
                     39: The associated files are named
                     40: .I "rmt0, ..., rmt15"
                     41: and
                     42: .I "nrmt0, ..., nrmt15."
                     43: .PP
                     44: Each
                     45: .I read
                     46: or
                     47: .I write
                     48: call reads or writes the next record on the tape.
                     49: In the write case the record has the same length as the
                     50: buffer given.
                     51: During a read, the record size is passed
                     52: back as the number of bytes read, provided it is no greater
                     53: than the buffer size;
                     54: if the record is long, an error is indicated.
                     55: In raw tape I/O, the buffer must begin on a word boundary
                     56: and the count must be even.
                     57: Seeks are ignored.
                     58: A zero count is returned when a tape mark is read;
                     59: another read will fetch the first record of the
                     60: next tape file.
                     61: .PP
                     62: In raw mode, the 
                     63: .I ioctl
                     64: system call can be used to access device special functions.
                     65: This call takes the form:
                     66: .I "ioctrl(fdes, code, count)."
                     67: Codes are defined in
                     68: .I "<sys/mt.h>,"
                     69: and consist of:
                     70: .in +8
                     71: .ti -3
                     72: SKIPF: Skip blocks, forward direction
                     73: .ti -3
                     74: SKIPR: Skip blocks, reverse direction
                     75: .ti -3
                     76: WEOF: Write EOF
                     77: .ti -3
                     78: REW: Rewind
                     79: .ti -3
                     80: SKIPFF: Skip one or more EOF's (skip forward file)
                     81: .ti -3
                     82: SKIPRF: Skip EOF marks or to BOT, reverse direction
                     83: .in -8
                     84: The
                     85: .I count
                     86: argument must be positive, and specifies the number of times
                     87: the selected operation is to be repeated.
                     88: .SH FILES
                     89: /dev/mt?,
                     90: /dev/rmt?
                     91: .SH "SEE ALSO"
                     92: tp(1)
                     93: .SH BUGS
                     94: The magtape system is supposed to be able
                     95: to take 64 drives.
                     96: Such addressing has never been tried.
                     97: These bugs will be fixed when
                     98: we get more experience with this device.
                     99: .PP
                    100: The driver is limited to four transports.
                    101: .PP
                    102: If any non-data error is encountered, it refuses to do anything
                    103: more until closed.

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.