RFC 110

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


   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         |
      $NOT ,           to translate to         @
      $NOT .           to translate to        $CENT
      $NOT =           to translate to         #

   To key in the ASCII control codes, it is recommended that the
   character escape followed by two letters be used to specify a control
   code.  These two letters are derived from the mnemonic name of the
   ASCII control function and are as follows:

      $NOT AC          to translate to         ACK             X'06'
      $NOT BE          to translate to         BEL             X'07'
      $NOT BS          to translate to         BS              X'08'
      $NOT CA          to translate to         CAN             X'18'
      $NOT CR          to translate to         CR              X'0D'
      $NOT D1          to translate to         DC1             X'11'
      $NOT D2          to translate to         DC2             X'12'
      $NOT D3          to translate to         DC3             X'13'
      $NOT D4          to translate to         DC4             X'14'
      $NOT DE          to translate to         DEL             X'7F'
      $NOT DL          to translate to         DLE             X'10'
      $NOT EM          to translate to         EM              X'19'
      $NOT EN          to translate to         ENQ             X'05'
      $NOT EO          to translate to         EOT             X'04'
      $NOT ES          to translate to         ESC             X'1B'
      $NOT EB          to translate to         ETB             X'17'
      $NOT EX          to translate to         ETX             X'03'
      $NOT FF          to translate to         FF              X'0C'
      $NOT FS          to translate to         FS              X'1C'
      $NOT GS          to translate to         GS              X'1D'
      $NOT HT          to translate to         HT              X'09'
      $NOT LF          to translate to         LF              X'0A'
      $NOT NA          to translate to         NAK             X'15'
      $NOT NU          to translate to         NUL             X'00'
      $NOT RS          to translate to         RS              X'1E'
      $NOT SI          to translate to         SI              X'0F'
      $NOT SO          to translate to         SO              X'0E'
      $NOT SH          to translate to         SOH             X'01'
      $NOT SP          to translate to         SP              X'20'
      $NOT ST          to translate to         STX             X'02'
      $NOT SU          to translate to         SUB             X'1A'
      $NOT SY          to translate to         SYN             X'16
      $NOT US          to translate to         US              X'1F'
      $NOT VT          to translate to         VT              X'0B'

Winett                                                          [Page 3]

RFC 110            Conventions for Using an IBM 2741       25 March 1971

   Note that the controls SP, BS, and HT can be specified using the
   character escape character or directly by keying the appropriate key
   on a 2741 terminal.


   [1] The following identifiers are substituted for graphics not in

         $CENT   Cent sign
         $NOT    Logical NOT ("bent bar")

   See the PDF version of this document for graphics that cannot be
   represented in ASCII format.

          [This RFC was put into machine readable form for entry]
          [into the online RFC archives by Lorrie Shiota, 10/02]

Winett                                                          [Page 4]