bk man page on OPENSTEP

Man page or keyword search:  
man Server   1419 pages
apropos Keyword Search (all sections)
Output format
OPENSTEP logo
[printable version]


BK(4)									 BK(4)

NAME
       bk - line discipline for machine-machine communication (obsolete)

SYNOPSIS
       pseudo-device bk

DESCRIPTION
       This  line  discipline  provides	 a replacement for the old and new tty
       drivers described in tty(4) when high speed output  to  and  especially
       input  from  another  machine  is to be transmitted over a asynchronous
       communications line.  The  discipline  was  designed  for  use  by  the
       Berkeley	 network.   It	may  be	 suitable  for	uploading of data from
       microprocessors into the system.	 If you are going to  send  data  over
       asynchronous  communications  lines  at high speed into the system, you
       must use this discipline, as the system otherwise may detect high input
       data  rates  on	terminal lines and disables the lines; in any case the
       processing of such data when normal terminal  mechanisms	 are  involved
       saturates the system.

       The line discipline is enabled by a sequence:

	    #include <sgtty.h>
	    int ldisc = NETLDISC, fildes; ...
	    ioctl(fildes, TIOCSETD, &ldisc);

       A  typical  application program then reads a sequence of lines from the
       terminal port, checking header and sequencing information on each  line
       and  acknowledging  receipt  of	each  line  to	the  sender,  who then
       transmits another line of data.	Typically  several  hundred  bytes  of
       data  and  a  smaller amount of control information will be received on
       each handshake.

       The old standard teletype discipline can be restored by doing:

	    ldisc = OTTYDISC;
	    ioctl(fildes, TIOCSETD, &ldisc);

       While in networked mode, normal teletype output functions  take	place.
       Thus,  if  an  8	 bit  output  data path is desired, it is necessary to
       prepare the output line by putting it into  RAW	mode  using  ioctl(2).
       This must be done before changing the discipline with TIOCSETD, as most
       ioctl(2) calls are disabled while in network line-discipline mode.

       When in network mode,  input  processing	 is  very  limited  to	reduce
       overhead.   Currently  the input path is only 7 bits wide, with newline
       the only recognized character, terminating an input record.  Each input
       record  must  be read and acknowledged before the next input is read as
       the system refuses to accept any new data when there is a record in the
       buffer.	 The buffer is limited in length, but the system guarantees to
       always be willing to accept input resulting in 512 data characters  and
       then the terminating newline.

       User  level  programs  should  provide  sequencing and checksums on the
       information to guarantee accurate data transfer.

SEE ALSO
       tty(4)

DIAGNOSTICS
       None.

BUGS
       The Purdue uploading line discipline, which provides 8  bits  and  uses
       timeout's  to  terminate	 uploading  should  be	incorporated  into the
       standard system,	 as  it	 is  much  more	 suitable  for	microprocessor
       connections.

4th Berkeley Distribution	 May 15, 1985				 BK(4)
[top]
                             _         _         _ 
                            | |       | |       | |     
                            | |       | |       | |     
                         __ | | __ __ | | __ __ | | __  
                         \ \| |/ / \ \| |/ / \ \| |/ /  
                          \ \ / /   \ \ / /   \ \ / /   
                           \   /     \   /     \   /    
                            \_/       \_/       \_/ 
More information is available in HTML format for server OPENSTEP

List of man pages available for OPENSTEP

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net