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Using TSO via ARPA Network Virtual Terminal :: RFC0377

NETWORK WORKING GROUP                                        R.T. BRADEN
REQUEST FOR COMMENTS #377                                       UCLA/CCN
NIC 11119                                                AUGUST 10, 1972


A.  Connecting to TSO

    IBM's Time Sharing Option (TSO) is available at UCLA-CCN on Socket 1
    using the standard Telnet protocol.

    1.  To access TSO, the remote user performs ICP to Socket 1 at CCN
        and executes the command:

                    TSO CR LF
                        -- --

    2.  Possible responses to the TSO command are:


            followed by a herald ("!").  TSO is available.   A TSO LOGON
            command should be entered following the herald.


            The user should check the TSO schedule and verify that it
            should be available. If so, he can call the CCN on-line help
            phone, 213-825-1652 for availability information, or send a
            message to the operator through NETRJS.

        c.  "ALL TSO PORTS BUSY"

            The user should try again after a short time. If this
            condition recurs frequently, notify the Technical Liaison at
            CCN so that more Network ports can be added.

Braden                                                          [Page 1]
RFC 377            Using TSO via Net Virtual Terminal        August 1972

    3.  When first connected to CCN server Telnet, the user has a choice
        of several commands besides "TSO". The TSO-related commands are:

            HELP    -  A listing of commands at this level, and other
                       general information.

            BBOARD  -  List operational notices.

    4.  Local echoing (i.e., by the user site) is required.

    5.  Server-Telnet will time-out and disconnect the user if:

        a.  Output to the Network does not complete within 5 minutes, or

        b.  An INS, DATA MARK pair does not match within 2 minutes, or

        c.  TSO waits for the user to enter input for 20 minutes.

B.  Conversing with TSO

    1.  TSO is strictly a line-at-a-time system.  Input is not scanned
        until either an end-of-line or an INS (interrupt) is received at
        CCN.  TSO sends the user an exclamation mark ("!") as a herald
        when waiting for input.

    2.  The end-of-line indication for input and output lines is the
        standard CR LF sequence.

    3.  The remote user my interrupt TSO output by sending an INS and
        DATA MARK (Telnet X'80').  Note to TIP users: this may be
        accomplished with the TIP command "SEND SYNC".  Each such
        interrupt is passed to TSO, which interprets it as an output
        break, i.e., as if the user pressed the ATTention key on his
        2741 while the keyboard was _locked_.

        On the Network, "attentions" are not used to delete lines being
        entered.  The CCN Server-Telnet provides line editing functions
        for TSO users: the ASCII control CAN deletes the line being
        entered, while BS deletes the preceding character.

    4.  There is a third interrupt case to be considered: suppose a
        program has placed the user's terminal into input state, but the
        user wants to suspend its execution and take control up a level
        without satisfying the pending input request.  This is supposed
        to be accomplished by sending an INS/DATA MARK pair.
        Unfortunately, due to a bug in our Network interface to TSO, the
        interrupt will be ignored in this case.  To circumvent this

Braden                                                          [Page 2]
RFC 377            Using TSO via Net Virtual Terminal        August 1972

        problem, we recommend that you define a software break string,
        such as "!!!!".  This may be accomplished with the command:

                    TERM INPUT (!!!!)

        Note that there are no quotes around the string.  You can enter
        this command when you first log on, and it will remain in effect
        for the session (or until you issue a new TERM command).  Then
        any input line containing four successive exclamation points
        will be interpreted as if an interrupt (attention) had been
        sent.  If that line contains other characters preceding the
        exclamation marks, the latter will be interpreted as line
        delete; otherwise, the result will be to take control up a

C.  Character Sets

    1.  Both upper and lower case input are allowed, but the server
        Telnet will translate all lower case to upper. Output is
        normally upper case.

    2.  Line-editing is provided by the Server-Telnet program before
        passing the input line to TSO.

                INPUT                    ACTION
                -----                    ------

                CAN (control X)          delete current line.

                BS (control H)           delete previous character on
                                         same line

                                         (NOTE: Telnet control char-
                                         acters are not deleted; they
                                         are bypassed in the backspace

                 HT (control I)          insert one space in input.

        All other ASCII controls are deleted from the input before
        line-editing is performed.

    3.  Input lines are translated to EBCDIC by the rules used for a
        NETRJS remote operator console (see Appendix B in RFC189).

Braden                                                          [Page 3]
RFC 377            Using TSO via Net Virtual Terminal        August 1972

        a.  ASCII controls are ignored except for BS, CAN, HT, and CR

        b.  The following correspondence is used for the EBCDIC graphics
            not in ASCII:

[In the original, the ASCII and EBCDIC graphics were handwritten; in  ]
[this version the ASCII graphics are typed and the EBCDIC graphics are]

                    ASCII                  TSO
                    -----                  ---
                      !                    (Vertical bar)

                      ~                    (EBCDIC "not")

                      \                    (Cent)

        c.  The six ASCII graphics not in EBCDIC are translated into
            EBCDIC question marks.

    4.  All Telnet controls except DATA MARK are ignored.


       [ This RFC was put into machine readable form for entry ]
       [ into the online RFC archives by Alex McKenzie with    ]
       [ support from GTE, formerly BBN Corp.             9/99 ]

Braden                                                          [Page 4]