Using TSO via ARPA Network Virtual Terminal
Instructions for connecting to UCLA-CCN's IBM Time Sharing Option over Telnet.
Braden, R.T., "Using TSO via ARPA Network Virtual Terminal", RFC 377, DOI 10.17487/RFC0377, August 1972, <https://www.rfc-editor.org/info/rfc377>.
@misc{rfc377,
series = {Request for Comments},
number = 377,
howpublished = {RFC 377},
publisher = {RFC Editor},
doi = {10.17487/RFC0377},
url = {https://www.rfc-editor.org/info/rfc377},
author = {R.T. Braden},
title = {{Using TSO via ARPA Network Virtual Terminal}},
pagetotal = 4,
year = 1972,
month = aug,
} RFC text
NETWORK WORKING GROUP R.T. BRADEN
REQUEST FOR COMMENTS #377 UCLA/CCN
NIC 11119 AUGUST 10, 1972
CATEGORIES:
OBSOLETES:
UPDATES:
USING TSO VIA ARPA NETWORK VIRTUAL TERMINAL
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:
a. "WELCOME TO UCLA/CCN TSO"
followed by a herald ("!"). TSO is available. A TSO LOGON
command should be entered following the herald.
b. "TSO NOT AVAILABLE AT THIS TIME"
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.
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
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
level.
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
operation.)
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).
Specifically:
a. ASCII controls are ignored except for BS, CAN, HT, and CR
LF.
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]
[omitted.]
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.
RTB/gjm
8/10/72
[ 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 ]
ISO Plain Language
On this page
§1Opening a TSO Session
UCLA-CCN makes IBM's Time Sharing Option (TSO) available on socket 1 using standard Telnet. A remote user performs the Initial Connection Protocol (ICP) to that socket and sends TSO CR LF.
A welcome message followed by ! means TSO is available, and the user should enter a TSO LOGON command. If TSO is unavailable, the user should check its schedule and contact the CCN help service if appropriate. If all TSO ports are busy, the user should try again later and report frequent recurrence to the Technical Liaison.
Connect to socket 1 and enter TSO followed by the line ending. The response tells you whether to log in, check the schedule, or try again later.
§2Entering Lines and Interrupting Output
TSO processes input one line at a time. It scans input after an end-of-line or an INS interrupt, and sends ! when it is waiting for input. The line ending is CR LF; local echoing at the user's site is required.
A user can interrupt TSO output with an INS and DATA MARK pair, using Telnet value X'80'. A TIP user can use SEND SYNC. The CCN server Telnet provides line editing: control-X deletes the current line, control-H deletes the previous character, and control-I inserts a space. The note lists disconnect timeouts of 5 minutes for incomplete output, 2 minutes for an unmatched interrupt pair, and 20 minutes while TSO waits for input.
TSO reads a complete line at a time and shows ! when it is ready for input. The guide lists keys for editing and a special signal for stopping output.
§3A Workaround for an Interrupt Bug
The memo describes a case where a program is waiting for terminal input and the user wants to suspend it without supplying that input. An INS/DATA MARK pair is supposed to transfer control to a higher level, but a bug in the network interface to TSO causes the interrupt to be ignored in this case.
The suggested workaround is to define a software break string with TERM INPUT (!!!!), without quotation marks. An input line containing four consecutive exclamation points then acts as an interrupt. If other characters come before the four marks, they act as a line delete instead.
One interrupt does not work while a program is waiting for input. The guide says to define four exclamation points as a substitute break string.
§4Character Translation and Editing
The server Telnet accepts upper- and lowercase input, translates lowercase to uppercase, and normally returns uppercase output. It performs line editing before passing input to TSO. Control-X deletes the current line, control-H deletes the previous character, and control-I inserts one space; other ASCII control characters are removed before editing.
Input is translated to EBCDIC using the rules for a NETRJS remote operator console in RFC 189. The memo gives mappings for some characters not shared by ASCII and EBCDIC, says six ASCII graphics without EBCDIC counterparts become question marks, and states that all Telnet controls except DATA MARK are ignored.
The server changes input to the character format TSO expects and handles several editing keys. The guide also lists how it treats characters and Telnet controls that TSO does not use.