Conventions for Using an IBM 2741 Terminal as a User Console for Access to Network Server Hosts
RFC 110

Document Type RFC - Unknown (March 1971; No errata)
Updated by RFC 135
Last updated 2013-03-02
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Network Working Group                                          J. Winett
Request for Comments: 110                         MIT Lincoln Laboratory
NIC: 5809                                                  25 March 1971

    Conventions for Using an IBM 2741 Terminal as a User Console for
                     Access to Network Server Hosts

   Disclaimer

   This material has not been reviewed for public release and is
   intended only for use with the ARPA network.  It should not be quoted
   or cited in any publication not related to the ARPA network.

   TO: NIC
   FROM: Joel M. Winnet (LL)
   SUBJECT: Conventions for Using an IBM 2741 Terminal as a User
   Console for Access to Network Server Hosts

   An IBM terminal can be used to key in 92 different codes.  These
   include 88 graphics plus the 4 controls SP, BS, HT, and NL.  Each of
   these have defined ASCII codes except the cent graphic ([1]) and the
   New Line Control (NL).  When the NL character is keyed, the program
   receiving the keyboard input can translate this signal into the
   appropriate line end signal for the host which is being used.  That
   is, to a NL, CR, or LF code whichever is appropriate.  There are 7
   other ASCII graphic characters ( {, }, [, ], ^, \, `) and 31 other
   ASCII controls which cannot be keyed on a 2741 terminal.  A
   convention must be established so that all 128 ASCII codes can be
   keyed from a 2741 terminal.  This requires that one character be
   chosen as an escape (or prefix) character which,a together with
   following characters, can be converted into any desired ASCII code.
   In addition to this escape character, there are three other functions
   which are usually indicated by the typing of a single character key.
   These are:

      a) character delete -- to cause this character and the preceding
         character in the input line to be deleted.

      b) line delete -- to cause this character and all previous
         characters in the current input line to be deleted.

      c) logical line end -- to cause all characters keyed after the
         last logical line end character or last NL character up to this
         character to be considered as one logical line with this
         character being treated as if the NL key were entered.
         Characters following the logical line end character up to
         another logical line end character or a NL character are used
         for form another input line.

Winett                                                          [Page 1]
RFC 110            Conventions for Using an IBM 2741       25 March 1971

   Since characters keyed are normally sent to the Server Host, a method
   must be defined to allow characters keyed to be interpreted by the
   user program.  A system escape character can be used for this
   purpose.  On character at a time systems, the characters keyed
   between two system escape characters can be interpreted by the user
   program.  On line at a time systems, characters keyed after the
   system escape character and up to and including a NL character can be
   interpreted by the user program.  Lines interpreted by the user
   program are not sent to the Server Host.

   For those host systems which require use of the INS or INR network
   control commands, a method must be defined for causing these commands
   to be sent.  These can be sent on a command to the user program
   either after keying the system escape character or through the use of
   the 'attention' button on a 2741 terminal.  This choice will depend
   on the characteristics of the terminal user's operating system.

   Other commands to the user program might be to:

      a) suppress typeout of received messages

      b) restore typeout of received messages

      c) direct received message to a disk file

      d) direct keyed input to a disk file

      e) abort the user program

   The following characters are recommended for the special functions
   listed above:

      1. character escape $NOT [1]
      2. system escape     |
      3. character delete  @
      4. line delete      $CENT [1]
      5. logical linend    #

   For the 7 ASCII graphics not on a 2741 terminal, the following
   character escape and graphic pairs are recommended:

      $NOT <           to translate to         [
      $NOT >           to translate to         ]
      $NOT (           to translate to         {
      $NOT )           to translate to         }
      $NOT "           to translate to         ^
      $NOT /           to translate to         \
      $NOT '           to translate to         `

Winett                                                          [Page 2]
RFC 110            Conventions for Using an IBM 2741       25 March 1971

   To permit the special function characters to be keyed, the following
   character escape and graphic pairs are recommended:

      $NOT -           to translate to        $NOT
      $NOT :           to translate to         |
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