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Annotation of 43BSDReno/share/man/man4/bk.4, revision 1.1

1.1     ! root        1: .\" Copyright (c) 1980 Regents of the University of California.
        !             2: .\" All rights reserved.  The Berkeley software License Agreement
        !             3: .\" specifies the terms and conditions for redistribution.
        !             4: .\"
        !             5: .\"    @(#)bk.4        6.1 (Berkeley) 5/15/85
        !             6: .\"
        !             7: .TH BK 4 "May 15, 1985"
        !             8: .UC 4
        !             9: .SH NAME
        !            10: bk \- line discipline for machine-machine communication (obsolete)
        !            11: .SH SYNOPSIS
        !            12: .B pseudo-device bk
        !            13: .SH DESCRIPTION
        !            14: This line discipline provides a replacement for the old and new
        !            15: tty drivers described in
        !            16: .IR tty (4)
        !            17: when high speed output to
        !            18: and especially input from another machine is to be transmitted
        !            19: over a asynchronous communications line.  The discipline
        !            20: was designed for use by the Berkeley network.
        !            21: It may be suitable for uploading of data from microprocessors into
        !            22: the system.  If you are going to send data over asynchronous
        !            23: communications lines at high speed into the system, you must
        !            24: use this discipline, as the system otherwise may detect high
        !            25: input data rates on terminal lines and disables the lines;
        !            26: in any case the processing of such data when normal terminal
        !            27: mechanisms are involved saturates the system.
        !            28: .PP
        !            29: The line discipline is enabled by a sequence:
        !            30: .PP
        !            31: .nf
        !            32: .ft B
        !            33:        #include <sgtty.h>
        !            34:        int ldisc = NETLDISC, fildes; ...
        !            35:        ioctl(fildes, TIOCSETD, &ldisc);
        !            36: .fi
        !            37: .ft R
        !            38: .PP
        !            39: A typical application program then reads a sequence of lines from
        !            40: the terminal port, checking header and sequencing information on each
        !            41: line and acknowledging receipt of each line to the sender, who then
        !            42: transmits another line of data.  Typically several hundred bytes of
        !            43: data and a smaller amount of control information will be received on
        !            44: each handshake.
        !            45: .PP
        !            46: The old standard teletype discipline can be restored by doing:
        !            47: .PP
        !            48: .nf
        !            49: .ft B
        !            50:        ldisc = OTTYDISC;
        !            51:        ioctl(fildes, TIOCSETD, &ldisc);
        !            52: .fi
        !            53: .ft R
        !            54: .PP
        !            55: While in networked mode, normal teletype output functions take place.
        !            56: Thus, if an 8 bit output data path is desired, it is necessary
        !            57: to prepare the output line by putting it into RAW mode using
        !            58: .IR ioctl (2).
        !            59: This must be done
        !            60: .B before
        !            61: changing the discipline with TIOCSETD, as most
        !            62: .IR ioctl (2)
        !            63: calls are disabled while in network line-discipline mode.
        !            64: .PP
        !            65: When in network mode, input processing is very limited to reduce overhead.
        !            66: Currently the input path is only 7 bits wide, with newline the only
        !            67: recognized character, terminating an input record.
        !            68: Each input record must be read and acknowledged before the next input
        !            69: is read as the system refuses to accept any new data when there
        !            70: is a record in the buffer.  The buffer is limited in length, but the
        !            71: system guarantees to always be willing to accept input resulting in
        !            72: 512 data characters and then the terminating newline.
        !            73: .PP
        !            74: User level programs should provide sequencing and checksums on the
        !            75: information to guarantee accurate data transfer.
        !            76: .SH "SEE ALSO"
        !            77: tty(4)
        !            78: .SH DIAGNOSTICS
        !            79: None.
        !            80: .SH BUGS
        !            81: The Purdue uploading line discipline, which provides 8 bits and uses
        !            82: timeout's to terminate uploading should be incorporated into the standard
        !            83: system, as it is much more suitable for microprocessor connections.

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